Energy storage frequency modulation control system, control method and control device based on electricity, water and steam

Abstract

The invention relates to an energy storage frequency modulation control system based on electricity, water and steam, which comprises a combined frequency modulation control system, an AGC control system, a unit DCS control system, an electric energy storage system, a water energy storage system and a steam energy storage system, and is characterized in that the combined frequency modulation control system is used for sending an instruction to realize coordinated frequency modulation control of the AGC control system, the electric energy storage system, the water energy storage system and the steam energy storage system. A unit AGC control and electricity, water and steam energy storage combined optimization intelligent control technology gives full play to the advantages of electricity, water and steam energy storage combined frequency modulation, optimizes steam turbine control valve control, reduces steam turbine throttling loss and boiler combustion fluctuation amplitude, and greatly improves the safety and environmental protection property of boiler operation while improving the unit operation economy.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage frequency modulation, and in particular to a control system, a control method and a control device based on electricity, water and steam energy storage frequency modulation. Background Art

[0002] Battery energy storage systems have fast response and can be adjusted in both directions, so they will not reverse the adjustment relative to thermal power units. According to calculations, the frequency regulation effect of energy storage is 1.7 times that of hydropower units, 2.5 times that of gas units, and more than 20 times that of coal-fired units. Although our factory has installed an electric energy storage frequency regulation system, it cannot fully play its role due to its small capacity and the need to optimize the operating mode. Therefore, a frequency regulation control system, control method and control device based on electric, water and steam energy storage are proposed. Through the unit AGC control and the intelligent control of electric, water and steam energy storage combined optimization, the advantages of the combined frequency regulation of electric, water and steam energy storage are fully utilized, the steam turbine regulating valve control is optimized, the throttling loss of the steam turbine and the fluctuation amplitude of the boiler combustion are reduced, and the economic efficiency of the unit operation is improved while the safety and environmental protection of the boiler operation are greatly improved. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a frequency modulation control system, a control method and a control device based on electricity, water and steam energy storage.

[0004] In a first aspect, the present invention provides a frequency regulation control system based on electricity, water and steam energy storage, including a joint frequency regulation control system, an AGC control system, a unit DCS control system, an electricity energy storage system, a water energy storage system and a steam energy storage system, wherein the joint frequency regulation control system is used to issue instructions to realize coordinated frequency regulation control of the AGC control system, the electricity energy storage system, the water energy storage system and the steam energy storage system;

[0005] The combined frequency regulation control system is a power plant motion device RTU;

[0006] The water energy storage system utilizes condensate water energy storage to realize frequency modulation function, and actively changes the condensate water flow rate during load change to cause changes in the heat absorption of the low-pressure heater, thereby changing the amount of steam doing work in the low-pressure cylinder of the steam turbine, realizing rapid rise and fall of the unit load, and utilizing condensate water throttling to realize short-term changes in the unit load;

[0007] The steam energy storage system uses extraction steam energy storage to realize the auxiliary frequency modulation function. A frequency modulation pneumatic regulating door is installed on the extraction steam pipeline. When the frequency modulation instruction requires a rapid increase in load, a command to close the extraction frequency modulation door is sent, and the extraction steam regulating door closes the frequency modulation range of 100-60%. Part of the extraction steam immediately returns to the steam turbine to perform work, realizing the function of rapid response to load frequency modulation. When the unit's low-pressure cylinder is cut off for heating, the heating extraction steam frequency modulation is changed to replace the condensate water joint frequency modulation;

[0008] The AGC control system is used for controlling boilers and steam turbines;

[0009] The electric energy storage system is used for charging and discharging switching of energy storage batteries.

[0010] Preferably, the power plant motion device RTU is responsible for system data acquisition, system model establishment, system model training, system control model optimization, and output of optimization control instructions for each system; through the big data collection of relevant performance parameters of the unit's electric energy storage frequency modulation, condensate water frequency modulation, high-pressure steam extraction frequency modulation and heating steam extraction frequency modulation, the operating characteristics of each subsystem are extracted, including response amplitude, response time and comprehensive response results, as well as Kp value and fluctuations in the unit's main parameters, turbine high-pressure regulating valve opening, etc., thereby establishing operation models of each subsystem and a comprehensive dynamic self-learning correction model, so that the performance of the comprehensive frequency modulation system is gradually optimized.

[0011] Preferably, the power plant motion device RTU uses MODBUS to achieve two-way data communication with the DCS.

[0012] Preferably, the boiler optimization control includes boiler main steam pressure, boiler main steam temperature, boiler reheat steam temperature and boiler air volume control. The control objective of boiler combustion optimization control is to improve the stability of the controlled parameters. Since each boiler combustion parameter has large inertia and delay, the boiler steady-state and dynamic models are used to advance the system adjustment parameter output. Through the system control accuracy, the sliding pressure operation mode of the unit under the AGC control mode is realized; the boiler main control control system optimizes the boiler main control in the form of master control instruction optimization compensation; the boiler main steam temperature, reheat steam temperature, and optimized control are achieved by outputting optimized cooling water control instructions.

[0013] Preferably, the AGC control of the unit's steam extraction frequency regulation is a coordinated control of three modes: deaerator water level, heating steam extraction, and high-pressure steam extraction. These three modes have common characteristics for the unit's frequency regulation: 1) The response speed of steam extraction regulation is fast, the adjustment range is limited, and it cannot be adjusted continuously in one direction. Due to the large delay and inertia of boiler combustion adjustment and the small delay and inertia of steam turbine adjustment, there is a time difference between the steam turbine and boiler load when the AGC changes rapidly. The goal of steam turbine steam extraction optimization control is to compensate for this time difference, thereby reducing the fluctuation of boiler combustion parameters. The intelligent optimization control system achieves rapid load adjustment by outputting the optimized deaerator water level constant and increasing or decreasing the condensate volume; the optimization control system outputs the optimization correction of the heating steam extraction flow constant, and changes the heating steam extraction volume to achieve rapid unit frequency regulation; high-pressure steam extraction adjustment is used as a special frequency regulation optimization means for the unit, and the optimization control system uses the optimized throttle valve command output to control its steam extraction volume.

[0014] Preferably, the joint frequency regulation control system collects the operating status of the energy storage battery, analyzes the compensation algorithm and characteristics of the electric energy storage equipment, calculates the operation of the electric energy storage equipment on the unit control deviation, coordinates the boiler main control and other auxiliary frequency regulation modes, and comprehensively improves the operating quality of the unit frequency regulation.

[0015] In a second aspect, the present invention provides a frequency regulation control method based on electricity, water and steam energy storage, characterized in that it includes the following regulation steps:

[0016] (1) The energy storage sets the energy storage output command at time t in real time with an appropriate compensation level to compensate for the real-time deviation between the unit output and the AGC command. The energy storage output power changes with the change of the unit output.

[0017] (2) The power grid dispatch center sends AGC instructions to the power plant motion device RTU;

[0018] (3) The RTU forwards the AGC instructions to the energy storage master control unit and the power plant DCS;

[0019] (4) The energy storage main control unit coordinates output with the unit based on AGC instructions and unit operating status information;

[0020] (5) The energy storage system control and communication access cannot affect the stability of the unit DCS controller. The energy storage system does not affect the response of the unit DCS to AGC instructions when it is connected or disconnected.

[0021] The third aspect of the present invention provides a frequency regulation control device based on electricity, water and steam energy storage. The electricity, water and steam energy storage frequency regulation system takes the intelligent optimization control system controller as the core, and is connected with the DCS system of each unit and the lithium battery energy storage device through a data network to realize data communication. The data network can be established using the MODBUS protocol or the OPC protocol. In order to improve the reliability of the system, a dual-network dual-machine structure with mutual backup can be adopted.

[0022] The beneficial effects of the present invention are:

[0023] 1. The unit's AGC control is combined with electricity, water (the low-pressure cylinder is cut off during heating and is changed to heating steam extraction frequency modulation), and steam energy storage to optimize the intelligent control technology, giving full play to the advantages of electricity, water, and steam energy storage combined frequency modulation, optimizing the steam turbine valve control, reducing turbine throttling losses and boiler combustion fluctuations, and greatly improving the safety and environmental protection of boiler operation while improving the unit's operating economy.

[0024] 2. According to the changes in unit load, season, heating mode and heating amount, intelligent sliding pressure operation is realized to effectively improve the economic efficiency of unit operation.

[0025] 3. Combined condensate (low-pressure cylinder cut-off during heating period is changed to heating steam extraction frequency regulation) and steam extraction energy storage frequency regulation technology to solve the problem of small electric energy storage capacity; at the same time, for 2 or 3 units, the intelligent optimization control technology of electricity, water and steam energy storage can be used to achieve flexible frequency regulation operation of multiple units, providing a means for the units to gain auxiliary frequency regulation benefits.

[0026] 4. Through the coordinated optimization of the combined frequency regulation control based on electricity, water and steam energy storage and the intelligent sliding pressure control of the unit, the adverse effects of the unilateral pursuit of frequency regulation capability on the boiler and steam turbine system can be effectively resolved, and the frequency regulation performance indicators can be relatively optimal; at the same time, the operating stability of boilers and environmental protection parameters is greatly improved, and it can be promoted and applied to the same type of frequency regulation thermal power units in the industry.

[0027] 5. This technology can reduce the fluctuation range of boiler parameters, improve the peak load capacity of the unit, and improve the efficiency of the steam turbine while ensuring the frequency regulation performance of the unit, thereby achieving the goal of energy saving and carbon reduction; at the same time, it can improve the operating flexibility of thermal power units, fully adapt to the spot market, and actively absorb new energy national strategic planning requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a control principle block diagram of the present invention;

[0029] Figure 2 It is a schematic diagram of the dynamic change process of condensate flow-unit load of the present invention; DETAILED DESCRIPTION

[0030] In order to clearly illustrate the technical features of this solution, this solution is described below through a specific implementation method.

[0031] like Figure 1-2 As shown, the frequency regulation control system based on electricity, water and steam energy storage includes a joint frequency regulation control system, an AGC control system, a unit DCS control system, an electricity energy storage system, a water energy storage system and a steam energy storage system. The joint frequency regulation control system is used to issue instructions to realize the coordinated frequency regulation control of the AGC control system, the electricity energy storage system, the water energy storage system and the steam energy storage system;

[0032] The combined frequency regulation control system is a power plant motion device RTU;

[0033] The water energy storage system utilizes condensate water energy storage to realize frequency modulation function. By actively changing the condensate water flow rate during load change, the heat absorption of low-pressure heating is changed, thereby changing the amount of steam working in the low-pressure cylinder of the steam turbine, realizing rapid rise and fall of the unit load, and utilizing condensate water throttling to realize short-term changes in the unit load; Figure 2It can be seen that when the condensate flow rate decreases rapidly, the actual load of the unit increases rapidly. In the condensate variable load system, this active adjustment and change is achieved by correcting the deaerator water level set value, that is, the original manually set deaerator water level set value signal is superimposed on the deaerator water level set value bias signal generated by the optimization system to form a new deaerator water level set value. In order to speed up the action response speed of the condensate pump active frequency conversion, the condensate pump frequency conversion control feedforward signal is also added, that is, the condensate pump frequency conversion feedforward formed after a series of judgments and calculations of the load command deviation is directly applied to the condensate pump frequency conversion output command. The system is equipped with a startup recovery control module, which is used to perform more refined startup and recovery control according to various command actions, so as to maximize the condensate frequency modulation effect and minimize the adverse effects of its lag. In addition, in order not to cause a major impact on the condensate system and even the entire unit, the condensate frequency modulation system has a maximum action time of no more than 120s. After one action is completed, the next action can only be triggered again when the system bias and feedforward have been restored. In addition, the condensate frequency modulation process will affect the regulation of the deaerator water level. When the unit reduces or increases the load for multiple consecutive times, the deviation of the deaerator water level may continue to increase or decrease and approach the control safety margin boundary of the deaerator water level, causing the condensate load variable capacity to be weakened or even disappear. Therefore, in the non-condensate frequency modulation adjustment range, a very small flow offset is set to slowly compensate for the water level deviation caused by the previous condensate load variable.

[0034] The steam energy storage system uses extraction steam energy storage to realize the auxiliary frequency modulation function. A frequency modulation pneumatic regulating door is installed on the extraction steam pipeline. When the frequency modulation instruction requires a rapid increase in load, a command to close the extraction frequency modulation door is sent, and the extraction steam regulating door closes the frequency modulation range of 100-60%. Part of the extraction steam immediately returns to the steam turbine to perform work, realizing the function of rapid response to load frequency modulation. When the unit's low-pressure cylinder is cut off for heating, the heating extraction steam frequency modulation is changed to replace the condensate water joint frequency modulation;

[0035] The AGC control system is used for controlling boilers and steam turbines;

[0036] The electric energy storage system is used for charging and discharging switching of energy storage batteries.

[0037] The power plant motion device RTU is responsible for system data collection, system model establishment, system model training, system control model optimization, and output of optimization control instructions for each system; through the big data collection of relevant performance parameters of the unit's electric energy storage frequency modulation, condensate water frequency modulation, high-pressure steam extraction frequency modulation, and heating steam extraction frequency modulation, the operating characteristics of each subsystem are extracted, including response amplitude, response time and comprehensive response results, as well as Kp value and fluctuations in the unit's main parameters, turbine high-pressure regulating valve opening, etc., thereby establishing the operation model of each subsystem and the comprehensive dynamic self-learning correction model, so that the comprehensive frequency modulation system can be gradually optimized.

[0038] The RTU of the power plant motion device uses MODBUS to achieve two-way data communication with the DCS.

[0039] Boiler optimization control includes boiler main steam pressure, boiler main steam temperature, boiler reheat steam temperature and boiler air volume control. The control goal of boiler combustion optimization control is to improve the stability of the controlled parameters. Since each boiler combustion parameter has large inertia and delay, the boiler steady-state and dynamic models are used to advance the system adjustment parameter output. Through the system control accuracy, the sliding pressure operation mode of the unit under the AGC control mode is realized; the boiler main control control system optimizes the boiler main control in the form of master control instruction optimization compensation; the boiler main steam temperature, reheat steam temperature, and optimized cooling water control instructions are output to achieve optimized control.

[0040] The AGC control of the unit's steam extraction frequency regulation is a coordinated control of three methods: deaerator water level, heating steam extraction, and high-pressure steam extraction. These three methods have common characteristics for the unit's frequency regulation: 1) The response speed of steam extraction regulation is fast, the adjustment range is limited, and it cannot be adjusted continuously in one direction. Due to the large delay and inertia of boiler combustion adjustment and the small delay and inertia of steam turbine adjustment, there is a time difference between the steam turbine and boiler load when the AGC changes rapidly. The goal of steam turbine extraction optimization control is to compensate for this time difference, thereby reducing the fluctuation of boiler combustion parameters. The intelligent optimization control system outputs the optimized deaerator water level constant value to increase or decrease the condensate volume to achieve rapid load adjustment; the optimization control system outputs the optimized correction of the heating steam extraction flow constant value to change the heating steam extraction volume to achieve rapid unit frequency regulation; high-pressure steam extraction adjustment is a special frequency regulation optimization method for the unit, and the optimization control system uses the optimized throttle valve command output to control its steam extraction volume.

[0041] The joint frequency regulation control system collects the operating status of the energy storage battery, analyzes the compensation algorithm and characteristics of the energy storage equipment, calculates the operation of the energy storage equipment on the unit control deviation, coordinates the boiler main control and other auxiliary frequency regulation methods, and comprehensively improves the operating quality of the unit frequency regulation.

[0042] The frequency regulation control method based on electricity, water and steam energy storage includes the following regulation steps:

[0043] (1) The energy storage sets the energy storage output command at time t in real time with an appropriate compensation level to compensate for the real-time deviation between the unit output and the AGC command. The energy storage output power changes with the change of the unit output.

[0044] (2) The power grid dispatch center sends AGC instructions to the power plant motion device RTU;

[0045] (3) The RTU forwards the AGC instructions to the energy storage master control unit and the power plant DCS;

[0046] (4) The energy storage main control unit coordinates output with the unit based on AGC instructions and unit operating status information;

[0047] (5) The energy storage system control and communication access cannot affect the stability of the unit DCS controller. The energy storage system does not affect the response of the unit DCS to AGC instructions when it is connected or disconnected.

[0048] Based on the frequency regulation control device of electricity, water and steam energy storage, the frequency regulation system of electricity, water and steam energy storage takes the intelligent optimization control system controller as the core, and connects with the DCS system of each unit and the lithium battery energy storage equipment through the data network to realize data communication. The data network can be established using the MODBUS protocol or the OPC protocol. In order to improve the reliability of the system, a dual-network dual-machine structure with mutual backup can be adopted.

[0049] AGC performance indicators

[0050] According to the requirements of the Implementation Rules for Auxiliary Services Management of Grid-connected Power Plants in North China, the regulation performance takes into account the comprehensive reflection of three factors: regulation rate, regulation accuracy and response time.

[0051] Each time AGC is activated, AGC is calculated according to the following formula.

[0052]

[0053] Adjusting speed

[0054]

[0055] ν N,j is the standard regulation rate of unit i, in megawatts per minute, ν i,j is the jth regulation rate of unit i. The standard regulation rate of direct-blowing units is 1.5% of the rated active power. Implement a maximum limit, and all values ​​above 1.2 will be calculated as 1.2 to prevent power generation companies from excessively pursuing compensation for ancillary services. value, causing adverse effects on the device.

[0056] According to the above formula, if Reaching the assessment index of 1.2, ν i,j The rated active power should be 1.875%. After the unit is optimized, the load rate of the unit is set to 2% of the rated active power, which can basically achieve The upper limit is 1.2.

[0057] Adjustment accuracy

[0058]

[0059] The allowable deviation is 1% (3.3MW) of the rated active power of the unit. In steady state, the load deviation is around 3-4MW, indicating There is a lot of room for improvement. It is recommended to strengthen the controller parameters of the steam turbine master control to control the steady-state load deviation within 1MW.

[0060] If it reaches 1.8, the regulation accuracy must reach 0.66MW. If it reaches 1.61, the regulation accuracy must reach 1.28MW.

[0061] Response time

[0062]

[0063] The standard response time of AGC for thermal power units should be less than 1 minute.

[0064] The response time of the energy storage battery reaches seconds, which is almost instantaneous. Considering the coordination with the variable load response characteristics of the unit, if it is set to start responding in 6 seconds and can be maintained for about 10 seconds, The index can reach 1.9.

[0065] If the comprehensive performance index of AGC assessment is to reach 3.67, It is enough to reach 1.61, and the regulation accuracy needs to reach 1.17MW. This reduces the pressure of precision control of the coordinated control system. However, it also puts forward higher requirements on the load response characteristics of the unit, and starts to respond stably in about 15s.

[0066] Of course, the above description is not limited to the above examples. Technical features not described in the present invention can be achieved by or by using existing technologies, which will not be described here. The above embodiments and drawings are only used to illustrate the technical scheme of the present invention and are not limitations of the present invention. The present invention is described in detail with reference to the preferred implementation methods. Ordinary technicians in this field should understand that changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention do not depart from the purpose of the present invention, and should also fall within the scope of protection of the claims of the present invention.

Claims

1. Based on the frequency modulation control system of electricity, water and steam energy storage, it is characterized by: It includes a joint frequency regulation control system, an AGC control system, a unit DCS control system, an electric energy storage system, a water energy storage system and a steam energy storage system. The joint frequency regulation control system is used to issue instructions to achieve coordinated frequency regulation control of the AGC control system, the electric energy storage system, the water energy storage system and the steam energy storage system. The combined frequency regulation control system is a power plant motion device RTU; The water energy storage system utilizes condensate water energy storage to realize frequency modulation function, and actively changes the condensate water flow rate during load change to cause changes in the heat absorption of the low-pressure heater, thereby changing the amount of steam doing work in the low-pressure cylinder of the steam turbine, realizing rapid rise and fall of the unit load, and utilizing condensate water throttling to realize short-term changes in the unit load; The steam energy storage system uses extraction steam energy storage to realize the auxiliary frequency modulation function. A frequency modulation pneumatic regulating door is installed on the extraction steam pipeline. When the frequency modulation instruction requires a rapid increase in load, a command to close the extraction frequency modulation door is sent, and the extraction steam regulating door closes the frequency modulation range of 100-60%. Part of the extraction steam immediately returns to the steam turbine to perform work, realizing the function of rapid response to load frequency modulation. When the unit's low-pressure cylinder is cut off for heating, the heating extraction steam frequency modulation is changed to replace the condensate water joint frequency modulation; The AGC control system is used for controlling boilers and steam turbines; The electric energy storage system is used for charging and discharging switching of energy storage batteries.

2. The frequency modulation control system based on electricity, water and steam energy storage according to claim 1 is characterized in that: The power plant motion device RTU is responsible for system data collection, system model establishment, system model training, system control model optimization, and output of optimization control instructions for each system; through the big data collection of relevant performance parameters of the unit's electric energy storage frequency modulation, condensate water frequency modulation, high-pressure steam extraction frequency modulation, and heating steam extraction frequency modulation, the operating characteristics of each subsystem are extracted, including response amplitude, response time and comprehensive response results, as well as Kp value and fluctuations in the unit's main parameters, turbine high-pressure regulating valve opening, etc., thereby establishing the operation model of each subsystem and the comprehensive dynamic self-learning correction model, so that the comprehensive frequency modulation system can be gradually optimized.

3. The frequency modulation control system based on electricity, water and steam energy storage according to claim 1 is characterized in that: The RTU of the power plant motion device uses MODBUS to achieve two-way data communication with the DCS.

4. The frequency modulation control system based on electricity, water and steam energy storage according to claim 1 is characterized in that: Boiler optimization control includes boiler main steam pressure, boiler main steam temperature, boiler reheat steam temperature and boiler air volume control. The control goal of boiler combustion optimization control is to improve the stability of the controlled parameters. Since each boiler combustion parameter has large inertia and delay, the boiler steady-state and dynamic models are used to advance the system adjustment parameter output. Through the system control accuracy, the sliding pressure operation mode of the unit under the AGC control mode is realized; the boiler main control control system optimizes the boiler main control in the form of master control instruction optimization compensation; the boiler main steam temperature, reheat steam temperature, and optimized cooling water control instructions are output to achieve optimized control.

5. The frequency modulation control system based on electricity, water and steam energy storage according to claim 1 is characterized in that: The unit's extraction steam frequency modulation AGC control utilizes the coordinated control of three modes: deaerator water level, heating extraction steam, and high-pressure extraction steam.

6. The frequency modulation control system based on electricity, water and steam energy storage according to claim 1 is characterized in that: The joint frequency regulation control system collects the operating status of the energy storage battery, analyzes the compensation algorithm and characteristics of the energy storage equipment, calculates the operation of the energy storage equipment on the unit control deviation, coordinates the boiler main control and other auxiliary frequency regulation methods, and comprehensively improves the operating quality of the unit frequency regulation.

7. A frequency modulation control method based on electricity, water and steam energy storage, characterized in that: The adjustment steps include: (1) The energy storage sets the energy storage output command at time t in real time with an appropriate compensation level to compensate for the real-time deviation between the unit output and the AGC command. The energy storage output power changes with the change of the unit output. (2) The power grid dispatch center sends AGC instructions to the power plant motion device RTU; (3) The RTU forwards the AGC instructions to the energy storage master control unit and the power plant DCS; (4) The energy storage main control unit coordinates output with the unit based on AGC instructions and unit operating status information; (5) The energy storage system control and communication access cannot affect the stability of the unit DCS controller. The energy storage system does not affect the response of the unit DCS to AGC instructions when it is connected or disconnected.

8. A frequency modulation control device based on electricity, water and steam energy storage, characterized in that: The electricity, water and steam energy storage frequency modulation system takes the intelligent optimization control system controller as the core, and connects with the DCS system of each unit and the lithium battery energy storage equipment through the data network to realize data communication. The data network can be established using the MODBUS protocol or the OPC protocol. In order to improve the reliability of the system, a dual-network dual-machine structure with mutual backup can be adopted.

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