Automated system of operational-remote control of the heat supply process. Industry analytical heat supply management system ACS "Teplo" Heat supply system management system

The introduction of automatic control systems (ACS) for heating, ventilation, hot water supply is the main approach to saving thermal energy. The installation of automatic control systems in individual heat points, according to the All-Russian Thermal Engineering Institute (Moscow), reduces heat consumption in the residential sector by 5-10%, and in administrative premises by 40%. The greatest effect is obtained due to optimal regulation in the spring-autumn period of the heating season, when the automation of central heating points practically does not fully fulfill its functionality. In the conditions of the continental climate of the Southern Urals, when during the day the difference in outside temperature can be 15-20 ° C, the introduction of automatic control systems for heating, ventilation and hot water supply becomes very relevant.

Building thermal management

Management of the thermal regime is reduced to maintaining it at a given level or changing it in accordance with a given law.

At thermal points, mainly two types of heat load are regulated: hot water supply and heating.

For both types of heat load, the ACP must maintain unchanged the setpoints for the temperature of hot water supply water and air in heated rooms.

A distinctive feature of heating regulation is its large thermal inertia, while the inertia of the hot water supply system is much less. Therefore, the task of stabilizing the air temperature in a heated room is much more difficult than the task of stabilizing the temperature of hot water in a hot water supply system.

The main disturbing influences are external meteorological conditions: outdoor temperature, wind, solar radiation.

There are the following fundamentally possible control schemes:

• regulation of the deviation of the internal temperature of the premises from the set one by influencing the flow of water entering the heating system;
• regulation depending on the perturbation of external parameters, leading to a deviation of the internal temperature from the set one;
• regulation depending on changes in the outside temperature and inside the room (by disturbance and by deviation).

Rice. 2.1 Structural diagram of room thermal management by room temperature deviation

On fig. 2.1 shows a block diagram of the control of the thermal regime of the room according to the deviation of the internal temperature of the premises, and in fig. 2.2 shows a block diagram of the control of the thermal regime of the room by perturbation of external parameters.

Rice. 2.2. Structural diagram of the control of the thermal regime of the room by perturbation of external parameters

Internal disturbing effects on the thermal regime of the building are insignificant.

For the disturbance control method, the following signals can be selected as signals to monitor the outside temperature:

• the temperature of the water entering the heating system;
• the amount of heat entering the heating system:
• coolant consumption.

ACP must take into account the following modes of operation of the district heating system, in which:

• the water temperature control at the heat source is not based on the current outdoor temperature, which is the main disturbing factor for the indoor temperature. The temperature of the network water at the heat source is determined by the air temperature over a long period, taking into account the forecast and the available heat output of the equipment. The transport delay, measured by the clock, also leads to a mismatch between the subscriber's network water temperature and the current outdoor temperature;
• hydraulic regimes of heating networks require limiting the maximum and sometimes the minimum consumption of network water for a thermal substation;
• the load of hot water supply has a significant impact on the operating modes of heating systems, leading to variable water temperatures during the day in the heating system or network water consumption for the heating system, depending on the type of heat supply system, the scheme for connecting hot water heaters and the heating scheme.

Disturbance control system

For a disturbance control system, it is characteristic that:

• there is a device that measures the magnitude of the disturbance;
• according to the results of measurements, the controller exercises a control effect on the flow rate of the coolant;
• the controller receives information about the temperature inside the room;
• the main disturbance is the outdoor air temperature, which is controlled by the ACP, so the disturbance will be called controlled.

Variants of control schemes for disturbance with the above tracking signals:

• regulation of the temperature of the water entering the heating system according to the current outdoor temperature;
• regulation of the flow of heat supplied to the heating system according to the current outdoor temperature;
• regulation of network water consumption according to the outdoor air temperature.

As can be seen from Figures 2.1, 2.2, regardless of the method of regulation, the automatic heat supply control system should contain the following main elements:

• primary measuring devices - temperature, flow, pressure, differential pressure sensors;
• secondary measuring devices;
• executive mechanisms containing regulatory bodies and drives;
• microprocessor controllers;
• heating devices (boilers, heaters, radiators).

ASR heat supply sensors

The main parameters of heat supply, which are maintained in accordance with the task with the help of automatic control systems, are widely known.

In heating, ventilation and hot water systems, temperature, flow, pressure, pressure drop are usually measured. In some systems, the heat load is measured. Methods and methods for measuring the parameters of heat carriers are traditional.

Rice. 2.3

On fig. 2.3 shows the temperature sensors of the Swedish company Tour and Anderson.

Automatic regulators

An automatic regulator is an automation tool that receives, amplifies and converts the shutdown signal of the controlled variable and purposefully influences the object of regulation.

Currently, digital controllers based on microprocessors are mainly used. In this case, usually in one microprocessor controller, several regulators for heating, ventilation and hot water supply systems are implemented.

Most domestic and foreign controllers for heat supply systems have the same functionality:

1. depending on the outdoor air temperature, the regulator provides the necessary temperature of the heat carrier for heating the building according to the heating schedule, controlling the control valve with an electric drive installed on the heating network pipeline;


2. automatic adjustment of the heating schedule is made in accordance with the needs of a particular building. For the greatest efficiency of heat saving, the supply schedule is constantly adjusted taking into account the actual conditions of the heat point, climate, and heat losses in the room;


3. the saving of the heat carrier at night is achieved due to the temporary method of regulation. Changing the task for a partial decrease in the coolant depends on the outside temperature so that, on the one hand, reduce heat consumption, on the other hand, do not freeze and warm up the room in time in the morning. At the same time, the moment of turning on the daytime heating mode, or intensive heating, is automatically calculated to achieve the desired room temperature at the right time;


4. the controllers make it possible to ensure the return water temperature as low as possible. This provides for the protection of the system from freezing;


5. the automatic correction set in the hot water system is performed. When the consumption in the domestic hot water system is low, large deviations in temperature are acceptable (increased dead band). This way the valve stem will not be changed too often and its service life will be extended. When the load increases, the dead zone automatically decreases, and the control accuracy increases;


6. alarm is triggered when the setpoints are exceeded. The following alarms are usually generated:
   • temperature alarm, in case of difference between the real and the set temperature;
   • an alarm from the pump comes in case of a malfunction;
   • alarm signal from the pressure sensor in the expansion tank;
   • a life-of-life alarm is triggered if the equipment has reached its end of life;
   • general alarm - if the controller has registered one or more alarms;


7. the parameters of the regulated object are registered and transferred to a computer.

Rice. 2.4

On fig. 2.4 microprocessor controllers ECL-1000 from Danfoss are shown.

Regulators

The actuator is one of the links of automatic control systems designed to directly influence the object of regulation. In the general case, the actuating device consists of an actuating mechanism and a regulating body.

Rice. 2.5

The actuator is the drive part of the regulatory body (Fig. 2.5).

In automatic heat supply control systems, mainly electrical (electromagnetic and electric motor) are used.

The regulatory body is designed to change the flow of matter or energy in the object of regulation. There are dosing and throttle regulating bodies. Dosing devices include such devices that change the flow rate of a substance by changing the performance of units (dosers, feeders, pumps).

Rice. 2.6

Throttle regulators (Fig. 2.6) are a variable hydraulic resistance that changes the flow rate of the substance by changing its flow area. These include control valves, elevators, secondary dampers, taps, etc.

Regulators are characterized by many parameters, the main of which are: throughput K v , nominal pressure P y , pressure drop across the regulator D y , and nominal passage D y .

In addition to the above parameters of the regulatory body, which mainly determine their design and dimensions, there are other characteristics that are taken into account when choosing a regulatory body, depending on the specific conditions of their use.

The most important is the flow characteristic, which establishes the dependence of the flow in relation to the movement of the valve at a constant pressure drop.

Throttle control valves are usually profiled with a linear or equal percentage flow characteristic.

With a linear bandwidth characteristic, the increase in bandwidth is proportional to the increment in gate movement.

With an equal-percentage bandwidth characteristic, the bandwidth increment (when the shutter movement changes) is proportional to the current bandwidth value.

Under operating conditions, the type of flow characteristic changes depending on the pressure drop across the valve. When assisted, the control valve is characterized by a flow characteristic, which is the dependence of the relative flow rate of the medium on the degree of opening of the regulating body.

The smallest value of the throughput, at which the throughput characteristic remains within the specified tolerance, is evaluated as the minimum throughput.

In many industrial process automation applications, the regulator must have a wide range of throughput, which is the ratio of the nominal throughput to the minimum throughput.

A necessary condition for the reliable operation of an automatic control system is the correct choice of the shape of the flow characteristic of the control valve.

For a specific system, the flow characteristic is determined by the values ​​of the parameters of the medium flowing through the valve and its throughput characteristic. In general, the flow characteristic differs from the flow characteristic, since the parameters of the medium (mainly pressure and pressure drop) usually depend on the flow rate. Therefore, the task of choosing the preferred flow characteristics of the control valve is divided into two stages:

1. selection of the form of the flow characteristics, ensuring the constancy of the transmission coefficient of the control valve in the entire range of loads;


2. selection of the form of the throughput characteristic, which provides the desired form of the flow characteristic for the given parameters of the medium.

When modernizing heating, ventilation and hot water supply systems, the dimensions of a typical network, the available pressure and the initial pressure of the medium are specified, the regulating body is chosen so that at a minimum flow rate through the valve, the loss in it corresponds to the excess pressure of the medium developed by the source, and the shape of the flow characteristic is close to given. The method of hydraulic calculation when choosing a control valve is quite laborious.

AUZhKH trust 42, in collaboration with SUSU, has developed a program for calculating and selecting regulatory bodies for the most common heating and hot water supply systems.

Circular pumps

Regardless of the scheme for connecting the heat load, a circulation pump is installed in the heating system circuit (Fig. 2.7).

Rice. 2.7. Circular pump (Grundfog).

It consists of a speed controller, an electric motor and the pump itself. The modern circulation pump is a glandless pump with a wet rotor that does not require maintenance. The engine control is usually carried out by an electronic speed controller designed to optimize the performance of the pump operating in conditions of increased external disturbances affecting the heating system.

The action of the circulation pump is based on the dependence of the pressure on the performance of the pump and, as a rule, has a quadratic character.

Circulation pump parameters:

• performance;
• maximum pressure;
• speed;
• speed range.

AUZhKH trust 42 has the necessary information on the calculation and selection of circulation pumps and can provide the necessary advice.

Heat exchangers

The most important elements of heat supply are heat exchangers. There are two types of heat exchangers: tubular and plate. Simplified, a tubular heat exchanger can be represented as two pipes (one pipe is inside the other rough). The plate heat exchanger is a compact heat exchanger assembled on a suitable frame of corrugated plates fitted with seals. Tubular and plate heat exchangers are used for hot water supply, heating and ventilation. The main parameters of any heat exchanger are:

• power;
• heat transfer coefficient;
• loss of pressure;
• maximum operating temperature;
• maximum working pressure;
• maximum flow.

Shell-and-tube heat exchangers have low efficiency due to low water flow rates in the tubes and annulus. This leads to low values ​​of the heat transfer coefficient and, as a result, unreasonably large dimensions. During the operation of heat exchangers, significant deposits in the form of scale and corrosion products are possible. In shell-and-tube heat exchangers, the elimination of deposits is very difficult.

Compared to tubular heat exchangers, plate heat exchangers are characterized by increased efficiency due to improved heat transfer between the plates, in which turbulent coolant flows flow countercurrently. In addition, the repair of the heat exchanger is quite simple and inexpensive.

Plate heat exchangers successfully solve the problems of preparing hot water in heating points with virtually no heat loss, so they are actively used today.

The principle of operation of plate heat exchangers is as follows. The liquids involved in the heat transfer process are introduced through the nozzles into the heat exchanger (Fig. 2.8).

Rice. 2.8

Gaskets, installed in a special way, ensure the distribution of liquids in the appropriate channels, eliminating the possibility of mixing flows. The type of corrugations on the plates and the configuration of the channel are selected in accordance with the required free passage between the plates, thus ensuring optimal conditions for the heat exchange process.

Rice. 2.9

The plate heat exchanger (Fig. 2.9) consists of a set of corrugated metal plates with holes in the corners for the passage of two fluids. Each plate is equipped with a gasket that limits the space between the plates and ensures the flow of liquids in this channel. The flow rate of coolants, the physical properties of liquids, pressure losses and temperature conditions determine the number and size of plates. Their corrugated surface contributes to an increase in turbulent flow. Contacting in intersecting directions, the corrugations support the plates, which are under conditions of different pressure from both coolants. To change the capacity (increase the heat load), a certain number of plates must be added to the heat exchanger package.

Summing up the above, we note that the advantages of plate heat exchangers are:

• compactness. Plate heat exchangers are more than three times more compact than shell and tube heat exchangers and more than six times lighter at the same power;
• ease of installation. Heat exchangers do not require a special foundation;
• low maintenance costs. The highly turbulent flow results in a low degree of pollution. New models of heat exchangers are designed in such a way as to extend the period of operation, which does not require repair, as much as possible. Cleaning and checking takes little time, since in the heat exchangers each heating sheet is taken out, which can be cleaned individually;
• efficient use of thermal energy. The plate heat exchanger has a high heat transfer coefficient, transfers heat from the source to the consumer with low losses;
• reliability;
• the ability to significantly increase the thermal load by adding a certain number of plates.

The temperature regime of the building as an object of regulation

When describing technological processes of heat supply, design schemes of statics are used that describe steady states, and design schemes of dynamics that describe transient modes.

The design schemes of the heat supply system determine the relationship between the input and output effects on the control object under the main internal and external disturbances.

A modern building is a complex heat and power system; therefore, simplifying assumptions are introduced to describe the temperature regime of a building.

• For multi-storey civil buildings, the part of the building for which the calculation is made is localized. Since the temperature regime in the building varies depending on the floor, the horizontal layout of the premises, the temperature regime is calculated for one or more of the most favorably located premises.


• The calculation of convective heat transfer in a room is derived from the assumption that the air temperature at each moment of time is the same throughout the entire volume of the room.


• When determining heat transfer through external enclosures, it is assumed that the enclosure or its characteristic part have the same temperature in planes perpendicular to the direction of air flow. Then the process of heat transfer through the outer enclosures will be described by a one-dimensional heat conduction equation.


• The calculation of radiant heat transfer in a room also allows a number of simplifications:

  a) we consider the air in the room to be a radiant medium;
  b) we neglect multiple reflections of radiant fluxes from surfaces;
  c) complex geometric shapes are replaced by simpler ones.



• Outdoor climate parameters:

  a) if the temperature regime of the premises is calculated at extreme values ​​of the outdoor climate indicators that are possible in a given area, then the thermal protection of the fences and the power of the microclimate control system will ensure stable compliance with the specified conditions;
  b) if we accept softer requirements, then in the room at some points in time there will be deviations from the design conditions.

Therefore, when assigning the design characteristics of the outdoor climate, it is mandatory to take into account the security of internal conditions.

AUZhKH Trust 42 specialists, together with SUSU scientists, have developed a computer program for calculating static and dynamic operating modes of subscriber bushings.

Rice. 2.10

On fig. 2.10 shows the main disturbing factors acting on the object of regulation (room). The heat Q source, coming from the heat source, performs the functions of a control action to maintain the room temperature T pom at the outlet of the object. Outside temperature T nar, wind speed V wind, solar radiation J rad, internal heat loss Q inside are disturbing influences. All these effects are functions of time and are random. The task is complicated by the fact that heat transfer processes are non-stationary and are described by differential equations in partial derivatives.

Below is a simplified design scheme of the heating system, which accurately describes the static thermal conditions in the building, and also allows you to qualitatively assess the impact of the main disturbances on the dynamics of heat transfer, to implement the main methods for regulating the processes of space heating.

Currently, studies of complex nonlinear systems (these include heat transfer processes in a heated room) are carried out using mathematical modeling methods. The use of computer technology to study the dynamics of the space heating process and possible control methods is an effective and convenient engineering method. The effectiveness of modeling lies in the fact that the dynamics of a complex real system can be studied using relatively simple application programs. Mathematical modeling allows you to explore the system with continuously changing its parameters, as well as perturbing influences. The use of modeling software packages for studying the heating process is especially valuable, since the study by analytical methods turns out to be very laborious and completely unsuitable.

Rice. 2.11

On fig. 2.11 shows fragments of the design scheme of the static mode of the heating system.

The figure has the following symbols:

1. t 1 (T n) - the temperature of the network water in the supply line of the power network;
2. T n (t) - outdoor temperature;
3. U - mixing ratio of the mixing unit;
4. φ - relative consumption of network water;
5. ΔT - design temperature difference in the heating system;
6. δt is the calculated temperature difference in the heating network;
7. T in - internal temperature of heated rooms;
8. G - consumption of network water at the heating point;
9. D p - water pressure drop in the heating system;
10. t - time.

With subscriber input with installed equipment for given calculated heating load Q 0 and daily schedule of hot water supply load Q r, the program allows you to solve any of the following tasks.

At an arbitrary outdoor temperature T n:

• determine the internal temperature of the heated premises T in, while the specified are the flow of network water or the input G with and the temperature graph in the supply line;
• determine the consumption of network water for input G c, required to provide a given internal temperature of heated premises T in with a known temperature graph of the heating network;
• determine the required water temperature in the supply line of the heating network t 1 (network temperature graph) to ensure the specified internal temperature of heated rooms T in at a given flow rate of network water G s. These tasks are solved for any heating system connection scheme (dependent, independent) and any hot water supply connection scheme (series, parallel, mixed).

In addition to the above parameters, water flow rates and temperatures are determined at all characteristic points of the scheme, heat flow rates for the heating system and thermal loads of both stages of the heater, and pressure losses of heat carriers in them. The program allows you to calculate the modes of subscriber inputs with any type of heat exchangers (shell and tube or plate).

Rice. 2.12

On fig. 2.12 shows fragments of the design scheme of the dynamic mode of the heating system.

The program for calculating the dynamic thermal regime of the building allows for subscriber input with the selected equipment for a given design heating load Q 0 to solve any of the following tasks:

• calculation of the control scheme for the thermal regime of the room according to the deviation of its internal temperature;
• calculation of the control scheme for the thermal regime of the room according to the perturbation of external parameters;
• calculation of the thermal regime of the building with qualitative, quantitative and combined methods of regulation;
• calculation of the optimal controller with non-linear static characteristics of real elements of the system (sensors, control valves, heat exchangers, etc.);
• with an arbitrarily time-varying outdoor temperature T n (t), it is necessary:
• determine the change in time of the internal temperature of the heated premises T in;
• determine the change in time of the flow of network water pa input G with required to provide a given internal temperature of the heated premises T in with an arbitrary temperature graph of the heating network;
• determine the change in time of the water temperature in the supply line of the heating network t 1 (t).

These tasks are solved for any heating system connection scheme (dependent, independent) and any hot water supply connection scheme (series, parallel, mixed).

Implementation of ASR for heat supply in residential buildings

Rice. 2.13

On fig. 2.13 shows a schematic diagram of an automatic control system for heating and hot water supply in an individual heating point (ITP) with dependent connection of the heating system and a two-stage scheme of hot water heaters. It was mounted by AUZhKH trust 42, passed tests and operational checks. This system is applicable to any connection scheme for heating and hot water systems of this type.

The main task of this system is to maintain a given dependence of the change in the consumption of network water for the heating and hot water supply system on the outside air temperature.

The connection of the heating system of the building to the heating networks is made according to a dependent scheme with pump mixing. For the preparation of hot water for the needs of hot water supply, it is planned to install plate heaters connected to the heating network according to a mixed two-stage scheme.

The heating system of the building is a two-pipe vertical system with a lower distribution of main pipelines.

The building's automatic heat supply control system includes solutions for:

• for automatic control of the operation of the external heat supply circuit;
• for automatic control of the operation of the internal circuit of the heating system of the building;
• to create a mode of comfort in the premises;
• for automatic control of the operation of the DHW heat exchanger.

The heating system is equipped with a microprocessor-based water temperature controller for the heating circuit of the building (internal circuit), complete with temperature sensors and a motorized control valve. Depending on the outdoor air temperature, the control device provides the required temperature of the heat carrier for heating the building according to the heating schedule, controlling the control valve with an electric drive installed on a direct pipeline from the heating network. To limit the maximum temperature of the return water returned to the heating network, a signal from a temperature sensor installed on the return water pipeline to the heating network is input to the microprocessor controller. The microprocessor controller protects the heating system from freezing. To maintain a constant differential pressure, a differential pressure regulator is provided on the temperature control valve.

To automatically control the air temperature in the premises of the building, the project provides for thermostats on heating devices. Thermoregulators provide comfort and save heat energy.

To maintain a constant differential pressure between the direct and return pipelines of the heating system, a differential pressure regulator is installed.

To automatically control the operation of the heat exchanger, an automatic temperature controller is installed on the heating water, which changes the supply of heating water depending on the temperature of the heated water entering the DHW system.

In accordance with the requirements of the "Rules for accounting for thermal energy and coolant" of 1995, commercial accounting of thermal energy was carried out at the input of the heating network to the ITP by means of a heat meter installed on the supply pipeline from the heating network and a volume meter installed on the return pipeline to the heating network.

The heat meter includes:

• flowmeter;
• CPU;
• two temperature sensors.

The microprocessor controller provides indication of parameters:

• quantity of heat;
• the amount of coolant;
• coolant temperature;
• temperature difference;
• operating time of the heat meter.

All elements of automatic control systems and hot water supply are made using Danfoss equipment.

The ECL 9600 microprocessor controller is designed to control the temperature regime of water in heating and hot water supply systems in two independent circuits and is used for installation at heating points.

The regulator has relay outputs for controlling control valves and circulation pumps.

Items to be connected to the ECL 9600 controller:

• outdoor air temperature sensor ESMT;
• temperature sensor at the coolant supply in the circulation circuit 2, ESMA/C/U;
• reversible drive of the control valve of the AMB or AMV series (220 V).

In addition, the following elements can be attached optionally:

• return water temperature sensor from the circulation circuit, ESMA/C/U;
• ESMR indoor air temperature sensor.

The ECL 9600 microprocessor controller has built-in analog or digital timers and an LCD display for easy maintenance.

The built-in indicator serves for visual observation of parameters and adjustment.

When an ESMR/F indoor air temperature sensor is connected, the temperature of the heating medium is automatically corrected at the supply to the heating system.

The controller can limit the value of the return water temperature from the circulation circuit in follow-up mode depending on the outdoor temperature (proportional limitation) or set a constant value for the maximum or minimum limitation of the return water temperature from the circulation circuit.

Comfort and heat saving features:

• lowering the temperature in the heating system at night and depending on the outdoor temperature or according to the set reduction value;
• the possibility of operating the system with increased power after each period of temperature decrease in the heating system (quick heating of the room);
• the possibility of automatic shutdown of the heating system at a certain set outdoor temperature (summer shutdown);
• the ability to work with various types of mechanized actuators of the control valve;
• remote control of the controller using ESMF/ECA 9020.

Protective features:

• limiting the maximum and minimum temperatures of the water supplied to the circulation circuit;
• pump control, periodic promenade in summer;
• protection of the heating system from freezing;
• the possibility of connecting a safety thermostat.

Modern equipment for automatic heat supply control systems

Domestic and foreign companies provide a wide range of modern equipment for automatic heat supply control systems with almost the same functionality:

1. Heating control:
   • Damping outdoor temperature.
   • Monday Effect.
   • Linear restrictions.
   • Return temperature limits.
   • Room temperature correction.
   • Self-correcting feed schedule.
   • Startup time optimization.
   • Economy mode at night.


2. DHW management:
   • Low load feature.
   • Return water temperature limit.
   • Separate timer.


3. Pump control:
   • Freeze protection.
   • Turn off the pump.
   • Pump exchange.


4. Alarms:
   • From the pump.
   • Freezing temperature.
   • General.

Sets of heat supply equipment from well-known companies, Danfoss (Denmark), Alfa Laval (Sweden), Tour and Anderson (Sweden), Raab Karcher (Germany), Honeywell (USA) generally include the following instruments and devices for control and accounting systems.

1. Equipment for automation of the heating point of the building:
   


2. Heat metering equipment.
   


3. Auxiliary equipment.
   • Check valves.
   • Ball valves are installed for hermetic shutdown of risers and for draining water. At the same time, in the open state, during the operation of the system, ball valves practically do not create additional resistance. They can also be installed on all branches at the entrance to the building and at the substation.
   • Drain ball valves.
   • A non-return valve is installed to prevent water from entering the return line from the supply line when the pump is stopped.
   • The mesh filter, with a ball valve on the drain, at the inlet to the system provides water purification from solid suspensions.
   • Automatic air vents provide automatic air release when filling the heating system, as well as during the operation of the heating system.
   • Radiators.
   • Convectors.
   • Intercoms ("Vika" AUZhKH trust 42).

The AUZhKH of trust 42 analyzed the functionality of the equipment of automatic heat supply control systems of the most famous companies: Danfoss, Tour and Anderson, Honeywell. Employees of the trust can provide qualified advice on the implementation of the equipment of these firms.

An important utility service in modern cities is heat supply. The heat supply system serves to meet the needs of the population in heating services for residential and public buildings, hot water supply (water heating) and ventilation.

The modern urban heat supply system includes the following main elements: a heat source, heat transmission networks and devices, as well as heat-consuming equipment and devices - heating, ventilation and hot water supply systems.

City heating systems are classified according to the following criteria:

• - degree of centralization;
• - type of coolant;
• - method of generating thermal energy;
• - method of supplying water for hot water supply and heating;
• - the number of pipelines of heating networks;
• - a way to provide consumers with thermal energy, etc.

By degree of centralization heat supply distinguish two main types:

• 1) centralized heat supply systems, which have been developed in cities and districts with predominantly multi-storey buildings. Among them are: highly organized centralized heat supply based on the combined generation of heat and electricity at CHP - district heating and district heating from district heating and industrial heating boilers;
• 2) decentralized heat supply from small adjoining boiler plants (attached, basement, roof), individual heating devices, etc.; at the same time, there are no heating networks and associated losses of thermal energy.

By coolant type Distinguish between steam and water heating systems. In steam heating systems, superheated steam acts as a heat carrier. These systems are mainly used for technological purposes in industry, power industry. For the needs of communal heat supply of the population due to the increased danger during their operation, they are practically not used.

In water heating systems, the heat carrier is hot water. These systems are used mainly for supplying thermal energy to urban consumers, for hot water supply and heating, and in some cases for technological processes. In our country, water heating systems account for more than half of all heating networks.

By method of generating heat energy distinguish:

• - Combined generation of heat and electricity at combined heat and power plants. In this case, the heat of the working thermal steam is used to generate electricity when the steam expands in the turbines, and then the remaining heat of the exhaust steam is used to heat water in the heat exchangers that make up the heating equipment of the CHP. Hot water is used for heating urban consumers. Thus, in a CHP plant, high-potential heat is used to generate electricity, and low-potential heat is used to supply heat. This is the energy meaning of the combined generation of heat and electricity, which provides a significant reduction in the specific fuel consumption in the production of heat and electricity;
• - separate generation of thermal energy, when heating water in boiler plants (thermal power plants) is separated from the generation of electrical energy.

By water supply method for hot water supply, water heating systems are divided into open and closed. In open water heating systems, hot water is supplied to the taps of the local hot water supply system directly from the heating networks. In closed water heating systems, water from heating networks is used only as a heating medium for heating in water heaters - heat exchangers (boilers) of tap water, which then enters the local hot water supply system.

By number of pipelines There are single-pipe, two-pipe and multi-pipe heat supply systems.

By way to provide consumers with thermal energy, single-stage and multi-stage heat supply systems are distinguished - depending on the schemes for connecting subscribers (consumers) to heating networks. The nodes for connecting heat consumers to heating networks are called subscriber inputs. At the subscriber input of each building, hot water heaters, elevators, pumps, fittings, instrumentation are installed to regulate the parameters and flow of the coolant according to local heating and water fittings. Therefore, often a subscriber input is called a local heating point (MTP). If a subscriber input is being constructed for a separate facility, then it is called an individual heating point (ITP).

When organizing single-stage heat supply systems, heat consumers are connected directly to heat networks. Such a direct connection of heating devices limits the limits of permissible pressure in heating networks, since the high pressure required to transport the coolant to end consumers is dangerous for heating radiators. Because of this, single-stage systems are used to supply heat to a limited number of consumers from boiler houses with a short length of heating networks.

In multistage systems, between the heat source and consumers, central heating centers (CHP) or control and distribution points (CDP) are placed, in which the parameters of the coolant can be changed at the request of local consumers. The central heating and distribution centers are equipped with pumping and water heating units, control and safety fittings, instrumentation designed to provide a group of consumers in a quarter or district with thermal energy of the required parameters. With the help of pumping or water heating installations, main pipelines (first stage) are partially or completely hydraulically isolated from distribution networks (second stage). From the CHP or KRP, a heat carrier with acceptable or established parameters is supplied through common or separate pipelines of the second stage to the MTP of each building for local consumers. At the same time, only elevator mixing of return water from local heating installations, local regulation of water consumption for hot water supply and metering of heat consumption are carried out in the MTP.

The organization of complete hydraulic isolation of heat networks of the first and second stages is the most important measure for improving the reliability of heat supply and increasing the range of heat transport. Multi-stage heat supply systems with central heating and distribution centers allow reducing the number of local hot water heaters, circulation pumps and temperature controllers installed in the MTP with a single-stage system by tens of times. In the central heating center, it is possible to organize the treatment of local tap water to prevent corrosion of hot water supply systems. Finally, during the construction of the central heating and distribution centers, the unit operating costs and the costs of maintaining personnel for servicing equipment in the MTP are significantly reduced.

Thermal energy in the form of hot water or steam is transported from a thermal power plant or boiler house to consumers (to residential buildings, public buildings and industrial enterprises) through special pipelines - heating networks. The route of heat networks in cities and other settlements should be provided in the technical lanes allocated for engineering networks.

Modern heating networks of urban systems are complex engineering structures. Their length from the source to consumers is tens of kilometers, and the diameter of the mains reaches 1400 mm. The structure of thermal networks includes heat pipelines; compensators that perceive temperature elongations; disconnecting, regulating and safety equipment installed in special chambers or pavilions; pumping stations; district heating points (RTP) and heating points (TP).

Heating networks are divided into main, laid on the main directions of the settlement, distribution - within the quarter, microdistrict - and branches to individual buildings and subscribers.

Schemes of thermal networks are used, as a rule, beam. In order to avoid interruptions in the supply of heat to the consumer, it is planned to connect individual main networks to each other, as well as to install jumpers between branches. In large cities, in the presence of several large heat sources, more complex heat networks are built according to the ring scheme.

To ensure the reliable functioning of such systems, their hierarchical construction is necessary, in which the entire system is divided into a number of levels, each of which has its own task, decreasing in value from the top level to the bottom. The upper hierarchical level is made up of heat sources, the next level is main heating networks with RTP, the lower one is distribution networks with subscriber inputs of consumers. Heat sources supply hot water of a given temperature and a given pressure to the heating networks, ensure the circulation of water in the system and maintain the proper hydrodynamic and static pressure in it. They have special water treatment plants, where chemical purification and deaeration of water is carried out. The main heat carrier flows are transported through the main heat networks to the heat consumption nodes. In the RTP, the coolant is distributed among the districts, autonomous hydraulic and thermal regimes are maintained in the networks of the districts. The organization of the hierarchical construction of heat supply systems ensures their controllability during operation.

To control the hydraulic and thermal modes of the heat supply system, it is automated, and the amount of heat supplied is regulated in accordance with consumption standards and subscriber requirements. The largest amount of heat is spent on heating buildings. The heating load changes with the outside temperature. To maintain the conformity of heat supply to consumers, it uses central regulation on heat sources. It is not possible to achieve a high quality of heat supply using only central regulation; therefore, additional automatic regulation is used at heating points and consumers. The water consumption for hot water supply is constantly changing, and in order to maintain a stable heat supply, the hydraulic mode of heat networks is automatically regulated, and the temperature of hot water is maintained constant and equal to 65 ° C.

The main systemic problems that complicate the organization of an effective mechanism for the functioning of heat supply in modern cities include the following:

• - significant physical and moral wear and tear of equipment of heat supply systems;
• - high level of losses in heat networks;
• - massive lack of heat energy meters and heat supply regulators among residents;
• - overestimated thermal loads of consumers;
• - imperfection of normative-legal and legislative base.

The equipment of thermal power plants and heating networks has a high degree of wear on average in Russia, reaching 70%. The total number of heating boiler houses is dominated by small, inefficient ones, the process of their reconstruction and liquidation proceeds very slowly. The increase in thermal capacities annually lags behind the increasing loads by 2 times or more. Due to systematic interruptions in the provision of boiler fuel in many cities, serious difficulties annually arise in the heat supply of residential areas and houses. Start-up of heating systems in the fall stretches for several months, "underheated" residential premises in the winter have become the norm, not the exception; the rate of equipment replacement is declining, the number of equipment in emergency condition is increasing. This predetermined in recent years a sharp increase in the accident rate of heat supply systems.

The article is devoted to the use of the Trace Mode SCADA system for operational remote control of district heating facilities in the city. The facility where the described project was implemented is located in the south of the Arkhangelsk region (the city of Velsk). The project provides for operational monitoring and management of the process of preparing and distributing heat for heating and supplying hot water to the city's vital facilities.

CJSC SpetsTeploStroy, Yaroslavl

Statement of the problem and the necessary functions of the system

The goal that our company faced was to build a main network for heating a large part of the city, using advanced construction methods, where pre-insulated pipes were used to build the network. For this, fifteen kilometers of main heating networks and seven central heating points (CHPs) were built. Purpose of the central heating station - using superheated water from the GT-CHP (according to the schedule 130/70 °С), it prepares the heat carrier for intra-quarter heating networks (according to the schedule 95/70 °С) and heats the water up to 60 °С for the needs of domestic hot water supply (hot water supply), The TsTP operates on an independent, closed scheme.

When setting the task, many requirements were taken into account that ensure the energy-saving principle of operation of the CHP. Here are some of the most important ones:

To carry out weather-dependent control of the heating system;

Maintain the DHW parameters at a given level (temperature t, pressure P, flow G);

Maintain at a given level the parameters of the coolant for heating (temperature t, pressure P, flow G);

Organize commercial accounting of thermal energy and heat carrier in accordance with the current regulatory documents (RD);

Provide ATS (automatic transfer of reserve) pumps (network and hot water supply) with motor resource equalization;

Perform correction of the main parameters according to the calendar and real time clock;

Perform periodic data transmission to the control room;

Perform diagnostics of measuring instruments and operating equipment;

Lack of staff on duty at the central heating station;

Monitor and promptly report to maintenance personnel on the occurrence of emergency situations.

As a result of these requirements, the functions of the operational-remote control system being created were determined. The main and auxiliary means of automation and data transmission were selected. A choice of SCADA-system was made to ensure the operability of the system as a whole.

Necessary and sufficient functions of the system:

1_Information functions:

Measurement and control of technological parameters;

Signaling and registration of parameter deviations from the established limits;

Formation and issuance of operational data to personnel;

Archiving and viewing the history of parameters.

2_Control functions:

Automatic regulation of important process parameters;

Remote control of peripheral devices (pumps);

Technological protection and blocking.

3_Service functions:

Self-diagnostics of software and hardware complex in real time;

Data transmission to the control room on schedule, upon request and in the event of an emergency;

Testing the operability and correct functioning of computing devices and input/output channels.

What influenced the choice of automation tools

and software?

The choice of basic automation tools was mainly based on three factors - this is the price, reliability and versatility of settings and programming. Thus, free programmable controllers of the PCD2-PCD3 series by Saia-Burgess were chosen for independent work in the central heating station and for data transmission. The domestic Trace Mode 6 SCADA system was chosen to create a control room. For data transmission, it was decided to use conventional cellular communication: use a conventional voice channel for data transmission and SMS messages to promptly notify personnel of emergency situations.

What is the working principle of the system

and features of the implementation of control in Trace Mode?

As in many similar systems, management functions for direct impact on regulatory mechanisms are given to the lower level, and already the management of the entire system as a whole is transferred to the upper one. I deliberately omit the description of the work of the lower level (controllers) and the process of data transfer and will go straight to the description of the upper one.

For ease of use, the control room is equipped with a personal computer (PC) with two monitors. Data from all points are collected on the dispatch controller and transmitted via the RS-232 interface to the OPC server running on a PC. The project is implemented in Trace Mode version 6 and is designed for 2048 channels. This is the first stage of the implementation of the described system.

A feature of the implementation of the task in Trace Mode is an attempt to create a multi-window interface with the ability to monitor the heat supply process in on-line mode, both on the city diagram and on the mnemonic diagrams of heat points. The use of a multi-window interface allows solving the problems of displaying a large amount of information on the dispatcher's display, which should be sufficient and at the same time non-redundant. The principle of a multi-window interface allows access to any process parameters in accordance with the hierarchical structure of windows. It also simplifies the implementation of the system at the facility, since such an interface is very similar in appearance to the widespread products of the Microsoft family and has similar menu equipment and toolbars familiar to any user of a personal computer.

On fig. 1 shows the main screen of the system. It schematically displays the main heating network with an indication of the heat source (CHP) and central heating points (from the first to the seventh). The screen displays information about the occurrence of emergency situations at the facilities, the current outdoor air temperature, the date and time of the last data transfer from each point. Heat supply objects are provided with pop-up hints. When an abnormal situation occurs, the object on the diagram starts to “blink”, and an event record and a red flashing indicator appear in the alarm report next to the date and time of data transmission. It is possible to view the enlarged thermal parameters for the CHP and for the entire heating network as a whole. To do this, disable the display of the list of the report of alarms and warnings (button "OTiP").

Rice. one. Main screen of the system. Scheme of the location of heat supply facilities in the city of Velsk

There are two ways to switch to the mnemonic diagram of a heat point - you need to click on the icon on the city map or on the button with the name of the heat point.

The mnemonic diagram of the substation opens on the second screen. This is done both for the convenience of monitoring a specific situation at the central heating station, and for monitoring the general state of the system. On these screens, all controlled and adjustable parameters are visualized in real time, including parameters that are read from heat meters. All technological equipment and measuring instruments are provided with pop-up hints in accordance with the technical documentation.

The image of equipment and automation means on the mnemonic diagram is as close as possible to the real view.

At the next level of the multi-window interface, you can directly control the heat transfer process, change settings, view the characteristics of the operating equipment, and monitor the parameters in real time with a history of changes.

On fig. 2 shows a screen interface for viewing and managing the main automation tools (control controller and heat meter). On the controller management screen, it is possible to change telephone numbers for sending SMS messages, prohibit or allow the transmission of emergency and information messages, control the frequency and amount of data transmission, and set parameters for self-diagnostics of measuring instruments. On the screen of the heat meter, you can view all settings, change available settings and control the mode of data exchange with the controller.

Rice. 2. Control screens for the Vzlet TSRV heat calculator and PCD253 controller

On fig. 3 shows pop-up panels for control equipment (control valve and pump groups). It displays the current status of this equipment, error details and some parameters needed for self-diagnosis and verification. So, for pumps, dry-running pressure, MTBF and start-up delay are very important parameters.

Rice. 3. Control panel for pump groups and control valve

On fig. 4 shows screens for monitoring parameters and control loops in graphical form with the ability to view the history of changes. All controlled parameters of the heat substation are displayed on the parameters screen. They are grouped according to their physical meaning (temperature, pressure, flow, amount of heat, heat output, lighting). All control loops of parameters are displayed on the screen of control loops and the current value of the parameter is displayed, given the dead zone, the position of the valve and the selected control law. All this data on the screens is divided into pages, similar to the generally accepted design in Windows applications.

Rice. four. Screens for graphic display of parameters and control loops

All screens can be moved across the space of two monitors while performing multiple tasks at the same time. All necessary parameters for trouble-free operation of the heat distribution system are available in real time.

How long has the system been in development?how many developers were there?

The basic part of the dispatching and control system in Trace Mode was developed within one month by the author of this article and launched in the city of Velsk. On fig. a photograph is presented from the temporary control room, where the system is installed and is undergoing trial operation. At the moment, our organization is putting into operation one more heating point and an emergency source of heat. It is at these facilities that a special control room is being designed. After its commissioning, all eight heat points will be included in the system.

Rice. 5. Temporary dispatcher's workplace

During the operation of the automated process control system, various comments and wishes from the dispatching service arise. Thus, the process of updating the system is constantly underway to improve the operational properties and convenience of the dispatcher.

What is the effect of introducing such a management system?

Advantages and disadvantages

In this article, the author does not set the task of assessing the economic effect of the introduction of a management system in numbers. However, the savings are obvious due to the reduction of personnel involved in the maintenance of the system, a significant reduction in the number of accidents. In addition, the environmental impact is obvious. It should also be noted that the introduction of such a system allows you to quickly respond and eliminate situations that may lead to unforeseen consequences. The payback period for the entire complex of works (construction of a heating main and heating points, installation and commissioning, automation and dispatching) for the customer will be 5-6 years.

The advantages of a working control system can be given:

Visual presentation of information on the graphic image of the object;

As for the animation elements, they were added to the project in a special way to improve the visual effect of viewing the program.

Prospects for the development of the system

The peculiarities of heat supply are the rigid mutual influence of heat supply and heat consumption modes, as well as the multiplicity of supply points for several goods (thermal energy, power, coolant, hot water). The purpose of heat supply is not to provide generation and transport, but to maintain the quality of these goods for each consumer.

This goal was achieved relatively effectively with stable coolant flow rates in all elements of the system. The “quality” regulation we use, by its very nature, implies changing only the temperature of the coolant. The emergence of demand-controlled buildings ensured the unpredictability of hydraulic regimes in networks while maintaining the constancy of costs in the buildings themselves. Complaints in the neighboring houses had to be eliminated by excessive circulation and the corresponding mass overflows.

The hydraulic calculation models used today, despite their periodic calibration, cannot provide for accounting for deviations in costs at building inputs due to changes in internal heat generation and hot water consumption, as well as the influence of sun, wind and rain. With the actual qualitative-quantitative regulation, it is necessary to “see” the system in real time and provide:

• control of the maximum number of delivery points;
• reconciliation of current balances of supply, losses and consumption;
• control action in case of unacceptable violation of modes.

Management should be as automated as possible, otherwise it is simply impossible to implement it. The challenge was to achieve this without undue expense of setting up checkpoints.

Today, when in a large number of buildings there are measuring systems with flow meters, temperature and pressure sensors, it is unreasonable to use them only for financial calculations. ACS "Teplo" is built mainly on the generalization and analysis of information "from the consumer".

When creating the automated control system, typical problems of outdated systems were overcome:

• dependence on the correctness of calculations of metering devices and the reliability of data in unverifiable archives;
• the impossibility of bringing together operational balances due to inconsistencies in the time of measurements;
• inability to control rapidly changing processes;
• non-compliance with the new information security requirements of the federal law "On the Security of the Critical Information Infrastructure of the Russian Federation".

Effects from the implementation of the system:

Consumer Services:

• determination of real balances for all types of goods and commercial losses:
• determination of possible off-balance sheet income;
• control of actual power consumption and its compliance with technical specifications for connection;
• introduction of restrictions corresponding to the level of payments;
• transition to a two-part tariff;
• monitoring KPIs for all services working with consumers and assessing the quality of their work.

Exploitation:

• determination of technological losses and balances in heat networks;
• dispatching and emergency control according to actual modes;
• maintaining optimal temperature schedules;
• monitoring the state of networks;
• adjustment of heat supply modes;
• control of shutdowns and violations of modes.

Development and investment:

• reliable assessment of the results of the implementation of improvement projects;
• assessment of the effects of investment costs;
• development of heat supply schemes in real electronic models;
• optimization of diameters and network configuration;
• reduction of connection costs, taking into account the real reserves of bandwidth and energy savings for consumers;
• renovation planning
• organization of joint work of CHP and boiler houses.

V. G. Semenov, Editor-in-Chief, Heat Supply News

The concept of a system

Everyone is used to the expressions "heat supply system", "control system", "automated control systems". One of the simplest definitions of any system: a set of connected operating elements. A more complex definition is given by Academician P. K. Anokhin: “A system can only be called such a complex of selectively involved components, in which the interaction acquires the character of mutual assistance to obtain a focused useful result.” Obtaining such a result is the goal of the system, and the goal is formed on the basis of need. In a market economy, technical systems, as well as their management systems, are formed on the basis of demand, that is, a need for which someone is willing to pay.

Technical heat supply systems consist of elements (CHP, boiler houses, networks, emergency services, etc.) that have very rigid technological connections. The "external environment" for the technical heat supply system are consumers of different types; gas, electric, water networks; weather; new developers, etc. They exchange energy, matter and information.

Any system exists within some limits imposed, as a rule, by buyers or authorized bodies. These are the requirements for the quality of heat supply, ecology, labor safety, price restrictions.

There are active systems that can withstand negative environmental impacts (unskilled actions of administrations of different levels, competition from other projects...), and passive systems that do not have this property.

Operational technical control systems for heat supply are typical human-machine systems, they are not very complex and are quite easy to automate. In fact, they are subsystems of a higher level system - heat supply management in a limited area.

Control systems

Management is the process of purposeful influence on the system, which ensures an increase in its organization, the achievement of one or another useful effect. Any control system is divided into control and controlled subsystems. The connection from the control subsystem to the controlled one is called direct connection. Such a connection always exists. The opposite direction of communication is called feedback. The concept of feedback is fundamental in technology, nature and society. It is believed that control without strong feedback is not effective, because it does not have the ability to self-detect errors, formulate problems, does not allow the use of the system's self-regulation capabilities, as well as the experience and knowledge of specialists.

SA Optner even believes that control is the goal of feedback. “Feedback affects the system. Impact is a means of changing the existing state of the system by excitation of a force that allows this to be done.

In a properly organized system, the deviation of its parameters from the norm or the deviation from the correct direction of development develops into feedback and initiates the management process. “The very deviation from the norm serves as an incentive to return to the norm” (P.K. Anokhin). It is also very important that the own purpose of the control system does not contradict the purpose of the controlled system, that is, the purpose for which it was created. It is generally accepted that the requirement of a "superior" organization is unconditional for a "lower" organization and is automatically transformed into a goal for it. This can sometimes lead to a substitution of the target.

The correct goal of the control system is the development of control actions based on the analysis of information about deviations, or, in other words, problem solving.

A problem is a situation of discrepancy between the desired and the existing. The human brain is arranged in such a way that a person begins to think in some direction only when a problem is revealed. Therefore, the correct definition of the problem predetermines the correct managerial decision. There are two categories of problems: stabilization and development.

Stabilization problems are called those, the solution of which is aimed at preventing, eliminating or compensating for disturbances that disrupt the current operation of the system. At the level of an enterprise, region or industry, the solution to these problems is referred to as production management.

The problems of development and improvement of systems are called those, the solution of which is aimed at improving the efficiency of functioning by changing the characteristics of the control object or control system.

From a systems perspective, a problem is the difference between the existing system and the desired system. The system that fills the gap between them is the object of construction and is called the solution to the problem.

Analysis of existing heat supply management systems

A systematic approach is an approach to the study of an object (problem, process) as a system in which elements, internal connections and connections with the environment are identified that affect the results of functioning, and the goals of each of the elements are determined based on the general purpose of the system.

The purpose of creating any centralized heat supply system is to provide high-quality, reliable heat supply at the lowest price. This goal suits consumers, citizens, administration and politicians. The same goal should be for the heat management system.

Today there is 2 main types of heat supply management systems:

1) the administration of the municipal formation or region and the heads of state heat supply enterprises subordinate to it;

2) governing bodies of non-municipal heat supply enterprises.

Rice. 1. Generalized scheme of the existing heat supply management system.

A generalized diagram of the heat supply control system is shown in fig. 1. It presents only those structures (environment) that can actually influence control systems:

Increase or decrease income;

Force to go to additional expenses;

Change the management of enterprises.

For a real analysis, we must start from the premise that only what is paid for or can be fired is performed, and not what is declared. State

There is practically no legislation regulating the activities of heat supply enterprises. Even the procedures for state regulation of local natural monopolies in heat supply are not spelled out.

Heat supply is the main problem in the reforms of housing and communal services and RAO "UES of Russia", it cannot be solved separately in either one or the other, therefore it is practically not considered, although these reforms should be interconnected precisely through heat supply. There is not even a government-approved concept for the development of the country's heat supply, let alone a real program of action.

The federal authorities do not regulate the quality of heat supply in any way, there are not even regulatory documents that define the quality criteria. Reliability of heat supply is regulated only through technical supervisory authorities. But since the interaction between them and the tariff authorities is not spelled out in any regulatory document, it is often absent. Enterprises, on the other hand, have the opportunity not to comply with any instructions, justifying this with a lack of funding.

Technical supervision according to existing regulatory documents is reduced to the control of individual technical units, and those for which there are more rules. The system in the interaction of all its elements is not considered, the measures that give the greatest system-wide effect are not identified.

The cost of heat supply is regulated only formally. Tariff legislation is so general that almost everything is left to the discretion of the federal and, to a greater extent, regional energy commissions. Heat consumption standards are regulated only for new buildings. There is practically no section on heat supply in state energy saving programs.

As a result, the role of the state was relegated to the collection of taxes and, through supervisory authorities, information to local authorities about the shortcomings in the heat supply.

For the work of natural monopolies, for the functioning of industries that ensure the possibility of the existence of the nation, the executive branch is responsible to the parliament. The problem is not that the federal bodies are functioning unsatisfactorily, but that there is actually no structure in the structure of the federal bodies, from