A control method for a thermal power and energy storage combined frequency regulation and capacity self-recovery system

Abstract

The present invention provides a control method for a thermal power energy storage combined frequency regulation and capacity self-recovery system, which changes the original control logic of the thermal power unit control system that is independent of the energy storage system parameters, and establishes a prediction mechanism for AGC instructions. The thermal power unit control system and the energy storage control system establish a real-time two-way communication mechanism for coordinated control and full complementarity; a stable regulation mode and an overshoot mode for the thermal power unit, and a frequency regulation mode and a self-recovery mode for the energy storage system are established, which maximizes the output of the thermal power unit while realizing the regulation of different powers under different charge states and capacity self-recovery of the energy storage system, breaking through the climbing limit of the thermal power unit and the frequency regulation limit of the energy storage system, improving the life of the energy storage system, improving the two-way frequency regulation capability of the energy storage system, and thereby improving the combined frequency regulation capability of the thermal power unit and the energy storage system.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and in particular relates to a control method for a thermal power energy storage combined frequency regulation and capacity self-recovery system. Background Art

[0002] The proportion of renewable energy generation in my country's power system is gradually increasing. However, the randomness, volatility, and intermittency of renewable energy generation limit the grid's ability to absorb it. Frequency regulation in my country's power system is primarily handled by coal-fired power plants, which have the weakest frequency regulation capabilities compared to hydropower and gas-fired units. Thermal power plants, when participating in frequency regulation, have low ramp rates and slow response times, making them struggle to follow frequency regulation commands and thus failing to maintain the required accuracy of frequency control. Furthermore, frequency regulation for traditional thermal power plants can negatively impact the unit's economics and stability. Energy storage systems offer fast response times, rapid ramp rates, and precise power control. Combining energy storage systems with thermal power units in automatic generation control (AGC) can significantly improve the response performance of thermal power plants. However, their primary limitations are their capacity and state of charge (SOC).

[0003] At present, the control strategy for the combined frequency regulation of thermal power and energy storage is generally one-way compensation, that is, the DCS system of the thermal power unit adjusts the unit output according to the AGC instructions in accordance with the conventional control strategy, without being affected by the energy storage system, and completely disregarding the energy state and power changes of the energy storage system; for the AGC instructions, there is no decomposition of the frequency regulation demand based on the size of the AGC instruction change and the prediction of the AGC instruction change. Most of the situations requiring fast rate response are completely borne by the battery. In particular, when the unit experiences continuous unidirectional load changes, its battery energy state will likely remain in a fully charged or empty state for a long time, basically losing the auxiliary response capability to instructions in a certain direction, which will greatly affect the frequency regulation performance of the entire system. energy; the energy storage system can only passively use the difference between the AGC command and the actual output of the unit as its output. If the energy storage system recovers energy, it can only give up responding to some grid commands; the energy storage system output generally adopts full power compensation, which causes the energy storage system to discharge or charge at full power for a long time, resulting in long-term overuse of the energy storage system, thus affecting the service life of the energy storage system; the control and monitoring of the thermal power unit and the energy storage system are still relatively independent, failing to give full play to the complementary role of the thermal power unit and the energy storage system and further improve the frequency regulation performance, which may cause the thermal power unit or the energy storage system to perform unnecessary adjustment processes, and also fails to fully consider the stability requirement of the energy storage system's charge state in an excellent two-way adjustment range. Summary of the Invention

[0004] The purpose of the present invention is to propose a control method for a thermal power and energy storage combined frequency regulation and capacity self-recovery system. This method changes the original control logic of the thermal power unit control system that is independent of the energy storage system parameters, and establishes a prediction mechanism for AGC instructions. The thermal power unit control system and the energy storage control system establish a real-time two-way communication mechanism for coordinated control and full complementarity. While maximizing the output of the thermal power unit, it also realizes the regulation of different powers and capacity self-recovery of the energy storage system under different charge states.

[0005] To achieve the above-mentioned object, the present invention proposes a control method for a thermal power generation and energy storage combined frequency regulation and capacity self-recovery system, characterized by comprising the following steps:

[0006] Step 1: The thermal power unit control system and the energy storage control system respectively receive the frequency regulation demand instruction (AGC instruction) issued by the power grid dispatching center through the power plant remote terminal unit, as well as the operating data of the thermal power unit and the energy storage system, and analyze and judge the received data; calculate and predict the AGC instruction based on the received AGC instruction, and calculate the AGC instruction based on the formula ΔP A =P AGC -P AGC-1 Calculate the update range of the AGC instruction; establish the prediction mechanism of the AGC instruction based on the historical database of the AGC instruction, and calculate the update range of the AGC instruction based on the formula ΔP A预 =P AGC预 -P AGC Calculate and predict the update amplitude of AGC instruction; set the secondary frequency modulation dead zone P d , P d The value of is less than or equal to 0.3% of the rated power of the thermal power unit; if the absolute value of the update amplitude is less than P d , then it is a microinstruction, if P d ≤Absolute value of update amplitude≤P max , then it is a medium instruction. If the absolute value of the update amplitude is greater than P max , then it is a large instruction; according to the formula ΔP=P AGC -P G , calculate the frequency modulation demand deviation of the current AGC instruction; determine the SOC of the energy storage system;

[0007] Step 2: The control system of the thermal power unit changes the original control logic that is irrelevant to the parameters of the energy storage system, and changes the control logic according to ΔP A , ΔP A预 , ΔP, SOC of energy storage system, P of thermal power unit G Calculate the parameters and send the main frequency regulation demand instruction P to the thermal power unit 主To achieve the main frequency regulation; the thermal power unit control system and the energy storage control system establish a real-time two-way communication mechanism, the thermal power unit control system obtains the SOC of the energy storage system in real time, and the energy storage control system obtains the output power of the thermal power unit in real time; the energy storage control system obtains the output power of the thermal power unit according to ΔP A , ΔP A预 , ΔP, SOC of energy storage system, P of thermal power unit G Calculate the parameters and send the frequency modulation demand instruction P to the energy storage system 次 , to achieve sub-frequency modulation;

[0008] Step 3: After receiving the main frequency regulation demand instruction, the thermal power unit adjusts the boiler or steam turbine parameters so that the output power of the thermal power unit responds to the main frequency regulation demand instruction, and sends the generator power to the energy storage control system in real time. At the same time, it receives the SOC and energy storage output power sent by the energy storage control system in real time. The frequency regulation of the thermal power unit is divided into stable regulation mode and overshoot mode. In stable regulation mode, the thermal power unit and the energy storage system jointly output to meet the requirements of the AGC instruction. In overshoot mode, the output of the thermal power unit is maximized while the capacity of the energy storage system is restored. After receiving the secondary frequency regulation demand instruction from the energy storage control system, the energy storage system responds to the secondary frequency regulation demand instruction by controlling the converter parameters. The frequency regulation of the energy storage system is divided into frequency regulation mode and self-recovery mode. Among them, the frequency regulation mode of the energy storage system is synchronized with the stable regulation mode of the thermal power unit, and the self-recovery mode of the energy storage system is synchronized with the overshoot mode of the thermal power unit.

[0009] Step 4: During the joint frequency regulation of the thermal power generation unit and the energy storage system, the joint frequency regulation of the thermal power generation unit and the energy storage system always meets the frequency regulation requirements of the AGC instruction. At the same time, it ensures that the energy storage system has appropriate two-way frequency regulation capabilities. After executing an AGC instruction, the frequency regulation performance is calculated. In order to quantitatively describe the effect of the joint frequency regulation of the thermal power generation unit and the energy storage system, the frequency regulation performance index M is defined, M= , and set the frequency regulation limit M0 of M. The smaller M is, the smaller the deviation of the thermal power unit and the energy storage system in coordinating the response to the AGC command is, and the better the frequency regulation effect is. When M>M0, repeat steps 1 to 4. When M<M0, the frequency regulation ends.

[0010] Furthermore, in step 3, the stable regulation mode of the thermal power unit determines the joint frequency regulation mode of the energy storage system and the thermal power unit based on the update amplitude of the AGC instruction and the SOC. When the AGC instruction is a microinstruction, the energy storage system takes priority in the joint frequency regulation, the thermal power unit does not produce power, and the power of the thermal power unit remains unchanged. The output power of the energy storage system is specifically determined based on the SOC until the combined power of the thermal power unit and the energy storage system is equal to the AGC instruction. However, when the output power corresponding to the SOC before the energy storage system responds is 0 or the SOC enters the range of output power 0 during the response process, the thermal power unit responds instead of the energy storage system; when the AGC instruction is a medium instruction, the thermal power unit and the energy storage system respond jointly, and the thermal power unit responds at a reference regulation rate. The value of the reference regulation rate is determined according to the frequency regulation demand deviation of the AGC instruction, and the reference regulation rate is positively correlated with the frequency regulation demand deviation of the AGC instruction. The power of the energy storage system is determined according to different SOCs until the combined power of the thermal power unit and the energy storage system is equal to the AGC instruction; when the AGC instruction is a large instruction, the thermal power unit and the energy storage system respond jointly, and the thermal power unit responds at a high regulation rate. The value of the high regulation rate is determined according to the frequency regulation demand deviation of the AGC instruction, and the high regulation rate is positively correlated with the frequency regulation demand deviation of the AGC instruction. The power of the energy storage system is determined according to different SOCs until the combined power of the thermal power unit and the energy storage system is equal to the AGC instruction.

[0011] Furthermore, in step 3, the energy storage system has different output powers at different states of charge (SOCs), and its capacity is limited. Charging power is low at extremely high SOCs, and discharging power is low at extremely low SOCs. This results in insufficient output at extreme SOCs, limiting system capacity recovery. Therefore, the maximum SOCmax and minimum SOCmin state of charge for the energy storage system, as well as the upper and lower limits SOC1 and SOC2 of the recovery target, are set to SOCmax ≥ 96%, SOCmin ≤ 4%, 47% ≤ SOC1 ≤ 50% ≤ SOC2 ≤ 53%. When SOC1 ≤ SOC ≤ SOC2, the energy storage system has bidirectional regulation capabilities.

[0012] Furthermore, in step 3, the frequency modulation mode of the energy storage system, the SOC of the energy storage system prioritizes the output of the energy storage system, and the dead zone is immediately activated under the current operating state and the output power is output at the output power of the SOC corresponding area. When the output power is positive, the energy storage system discharges, and when the output power is negative, the energy storage system charges; when charging, when SOC≤SOC2, the output power of the energy storage system is -P RBWhen SOC2≤SOC≤SOCmax, the output power of the energy storage system is a linear function of SOC. The output power decreases as SOC increases. When SOC≥SOCmax, the output power of the energy storage system is 0. When discharging, when SOC≤SOCmin, the output power of the energy storage system is 0. When SOC min When SOC≤SOC1, the output power of the energy storage system is a linear function of SOC, and the output power increases with the increase of SOC. When SOC≥SOC1, the output power of the energy storage system is P RB .

[0013] Furthermore, in step 3, when the steady-state mode of the thermal power unit is completed, it enters the overshoot mode. If ΔP A预 With ΔP A If both are greater than zero or both are less than zero, then P AGC预 With P AGC Positive correlation; on the contrary, P AGC预 With P AGC Negative correlation; regardless of ΔP A Is it greater than zero or less than zero? If ΔP A预 is equal to 0, then P AGC预 With P AGC Zero correlation; when P AGC预 With P AGC When the correlation is positive or negative, the overshoot coefficient f ranges from 0.1 to 0.3; when P AGC预 With P AGC When the correlation is zero, the value range of the overshoot coefficient f is 0~0.2; the specific overshoot coefficient is determined according to P AGC预 With P AGC and the SOC determination of the energy storage system.

[0014] Furthermore, in step 3, in overshoot mode, P AGC预 With P AGC Positive or negative correlation: when the thermal power unit just enters the overshoot mode and the energy storage system's SOC≤SOCmin or SOC≥SOCmax, 0.25<f<0.3; when the thermal power unit just enters the overshoot mode and the energy storage system's SOCmin≤SOC≤SOC1 or SOC2≤SOC≤SOCmax, 0.15<f<0.25; when the thermal power unit just enters the overshoot mode and the energy storage system's SOC1≤SOC≤SOC2, 0.1<f<0.15; P AGC预 With P AGCWhen the correlation is zero, when the energy storage system SOC≤SOCmin or SOC≥SOCmax when the thermal power unit just enters the overshoot mode, 0.15<f<0.2, when the energy storage system SOCmin≤SOC≤SOC1 or SOC2≤SOC≤SOCmax when the thermal power unit just enters the overshoot mode, 0.05<f<0.15, when the energy storage system SOC1≤SOC≤SOC2 when the thermal power unit just enters the overshoot mode, f=0.

[0015] Furthermore, in step 3, after the thermal power unit enters the overshoot mode, the thermal power unit continues to increase or decrease at the standard rate, the energy storage system enters the self-recovery mode, and the output power of the energy storage system gradually decreases or increases. During the process of the energy storage system gradually exiting, the joint frequency regulation of the thermal power unit and the energy storage system always meets the frequency regulation demand instruction P AGC When the output power of the thermal power unit independently meets the frequency regulation demand instruction P AGC After the demand is met, the energy storage system output power is zero, the thermal power unit continues to operate in overshoot mode, and the energy storage system begins to perform capacity self-recovery.

[0016] Furthermore, in step 3, if P AGC预 With P AGC If the actual correlation is different from the predicted correlation, the energy storage system immediately exits the self-recovery mode and enters the regulation mode.

[0017] Furthermore, in step 3, the time for the thermal power unit to complete the steady-state mode and the overshoot mode depends on the regulation rate of the thermal power unit. The baseline regulation rate is set to 1%-1.5% MW / min of the rated power of the thermal power unit, and the high regulation rate is set to 1.5%-2% MW / min of the rated power of the thermal power unit.

[0018] Furthermore, in step 3, the self-recovery mode is established on the basis of the overshoot mode of the thermal power unit and is determined according to the SOC of the energy storage system. The self-recovery mode is divided into four modes: strong charging, strong discharging, unidirectional adaptive, and bidirectional adaptive. When SOC≤SOCmin, the energy storage system is in the strong charging mode; when SOC≥SOCmax, the energy storage system is in the strong discharging mode; when SOCmin≤SOC≤SOC1 or SOC2≤SOC≤SOCmax, the energy storage system is in the unidirectional adaptive mode; when SOC1≤SOC≤SOC2, the energy storage system is in the bidirectional adaptive mode.

[0019] Furthermore, in step 3, in the forced charge or forced discharge mode in the self-recovery mode, while the thermal power unit satisfies the AGC instruction, the overshoot of the thermal power unit prioritizes compensating the energy storage system capacity, so that the SOC of the energy storage system is restored to the SOC corresponding to the unidirectional adaptive mode as soon as possible. When the SOC of the energy storage system changes, the self-recovery mode of the energy storage system is switched accordingly; in the unidirectional adaptive mode in the self-recovery mode, while the thermal power unit satisfies the AGC instruction, the energy storage system capacity is restored at a ratio of not less than 40%; in the bidirectional adaptive mode in the self-recovery mode, the thermal power unit prioritizes satisfying the AGC instruction, and the energy storage system capacity is not restored.

[0020] Furthermore, in step 3, the thermal power unit completes the overshoot capacity corresponding to the overshoot coefficient or the SOC of the energy storage system is in the bidirectional suitable zone. If either of the two conditions is met, the overshoot mode ends.

[0021] Through the above technical solution, the present invention has the following beneficial effects: the present invention changes the original control logic of the thermal power unit control system that is independent of the energy storage system parameters, and establishes a prediction mechanism for AGC instructions. The thermal power unit control system and the energy storage control system establish a real-time two-way communication mechanism for coordinated control and full complementarity; a stable regulation mode and an overshoot mode for the thermal power unit, and a frequency regulation mode and a self-recovery mode for the energy storage system are established. While maximizing the output of the thermal power unit, the present invention realizes the regulation of different powers under different charge states and the self-recovery of the capacity of the energy storage system, breaking through the climbing limit of the thermal power unit and the frequency regulation limit of the energy storage system, improving the life of the energy storage system, improving the two-way frequency regulation capability of the energy storage system, and thereby improving the joint frequency regulation capability of the thermal power unit and the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The invention will be explained in more detail below with the aid of the accompanying drawings, in which the same reference numerals refer to the same elements.

[0023] Figure 1 The present invention is a control flow chart showing a control method of a thermal power energy storage combined frequency regulation and capacity self-recovery system.

[0024] Figure 2 This is a detailed diagram showing a control method for a thermal power and energy storage combined frequency regulation and capacity self-recovery system. DETAILED DESCRIPTION

[0025] The following describes the embodiments of the present invention in detail with reference to the accompanying drawings. The embodiments and features of the embodiments of the present invention may be combined with each other unless there is a conflict. It should be noted that it is possible for other persons skilled in the art to modify or alter the present invention without departing from the principles of the present invention, and such modifications or alterations are also within the scope of protection of the claims of the present invention.

[0026] like Figure 1 As shown, the present invention proposes a control method for a thermal power energy storage combined frequency regulation and capacity self-recovery system, which is characterized by comprising the following steps:

[0027] Step 1: The thermal power unit control system and the energy storage control system respectively receive the frequency regulation demand instruction (AGC instruction) issued by the power grid dispatching center through the power plant remote terminal unit, as well as the operating data of the thermal power unit and the energy storage system, and analyze and judge the received data; calculate and predict the AGC instruction based on the received AGC instruction, and calculate the AGC instruction based on the formula ΔP A =P AGC -P AGC-1 Calculate the update range of the AGC instruction; establish the prediction mechanism of the AGC instruction based on the historical database of the AGC instruction, and calculate the update range of the AGC instruction based on the formula ΔP A预 =P AGC预 -P AGC Calculate and predict the update amplitude of AGC instruction; set the secondary frequency modulation dead zone P d , P d The value of is less than or equal to 0.3% of the rated power of the thermal power unit; if the absolute value of the update amplitude is less than P d , then it is a microinstruction, if P d ≤Absolute value of update amplitude≤P max , then it is a medium instruction. If the absolute value of the update amplitude is greater than P max , then it is a large instruction; according to the formula ΔP=P AGC -P G , calculate the frequency modulation demand deviation of the current AGC instruction; determine the SOC of the energy storage system;

[0028] Step 2: The control system of the thermal power unit changes the original control logic that is irrelevant to the parameters of the energy storage system, and changes the control logic according to ΔP A , ΔP A预 , ΔP, SOC of energy storage system, P of thermal power unit G Calculate the parameters and send the main frequency regulation demand instruction P to the thermal power unit 主 To achieve the main frequency regulation; the thermal power unit control system and the energy storage control system establish a real-time two-way communication mechanism, the thermal power unit control system obtains the SOC of the energy storage system in real time, and the energy storage control system obtains the output power of the thermal power unit in real time; the energy storage control system obtains the output power of the thermal power unit according to ΔP A , ΔP A预 , ΔP SOC of energy storage system, P of thermal power unit G Calculate the parameters and send the frequency modulation demand instruction P to the energy storage system 次 , to achieve sub-frequency modulation;

[0029] Step 3: After receiving the main frequency regulation demand instruction, the thermal power unit adjusts the boiler or steam turbine parameters so that the output power of the thermal power unit responds to the main frequency regulation demand instruction, and sends the generator power to the energy storage control system in real time. At the same time, it receives the SOC and energy storage output power sent by the energy storage control system in real time. The frequency regulation of the thermal power unit is divided into stable regulation mode and overshoot mode. In stable regulation mode, the thermal power unit and the energy storage system jointly output to meet the requirements of the AGC instruction. In overshoot mode, the output of the thermal power unit is maximized while the capacity of the energy storage system is restored. After receiving the secondary frequency regulation demand instruction from the energy storage control system, the energy storage system responds to the secondary frequency regulation demand instruction by controlling the converter parameters. The frequency regulation of the energy storage system is divided into frequency regulation mode and self-recovery mode. Among them, the frequency regulation mode of the energy storage system is synchronized with the stable regulation mode of the thermal power unit, and the self-recovery mode of the energy storage system is synchronized with the overshoot mode of the thermal power unit.

[0030] Step 4: During the joint frequency regulation process between the thermal power generation unit and the energy storage system, the combined frequency regulation of the thermal power generation unit and the energy storage system consistently meets the frequency regulation requirements of the AGC command, while also ensuring that the energy storage system possesses appropriate bidirectional frequency regulation capabilities. After executing an AGC command, the frequency regulation performance is calculated. To quantitatively describe the effect of the combined frequency regulation of the thermal power generation unit and the energy storage system, a frequency regulation performance index M is defined, M = , and a frequency regulation limit M0 is set for M. The smaller M, the smaller the deviation in the coordinated response of the thermal power generation unit and the energy storage system to the AGC command, and the better the frequency regulation effect. When M>M0, steps 1-4 are repeated. When M<M0, the frequency regulation ends.

[0031] like Figure 2 As shown, in the frequency modulation mode of the energy storage system, the SOC of the energy storage system first determines the output of the energy storage system. In the current operating state, the dead zone is immediately activated and the output power is output at the output power corresponding to the SOC area. When the output power is positive, the energy storage system discharges, and when the output power is negative, the energy storage system charges. When charging, when SOC≤SOC2, the output power of the energy storage system is -P RB When SOC2≤SOC≤SOCmax, the output power of the energy storage system is a linear function of SOC. The output power decreases as SOC increases. When SOC≥SOCmax, the output power of the energy storage system is 0. When discharging, when SOC≤SOCmin, the output power of the energy storage system is 0. When SOC min When SOC≤SOC1, the output power of the energy storage system is a linear function of SOC, and the output power increases with the increase of SOC. When SOC≥SOC1, the output power of the energy storage system is P RB .

[0032] Example 1: The rated output power of the thermal power unit is 600MW, the rated output power of the energy storage system is 18MW, the last AGC instruction is 575MW, the current AGC instruction is 590MW, the predicted AGC instruction is 600MW, and the actual output power of the current thermal power unit is 575MW. At this time, the update amplitude of the AGC instruction ΔP A The update amplitude of the AGC command is 15MW, and the predicted update amplitude ΔP A预 The frequency regulation demand deviation ΔP of the AGC instruction is 10MW, and the SOC of the energy storage system is 3%. According to ΔP A , ΔP A预 , ΔP SOC of energy storage system, P of thermal power unit G Calculate the frequency modulation demand instruction P using other parameters 主 and sub-frequency modulation demand instruction P 次 After the thermal power unit receives the main frequency regulation demand instruction, it adjusts the boiler or steam turbine parameters to make the thermal power unit respond to the main frequency regulation demand instruction. The frequency regulation of the thermal power unit is divided into stable regulation mode and overshoot mode. After the energy storage system receives the secondary frequency regulation demand instruction, it responds to the secondary frequency regulation demand instruction by controlling the converter parameters. The frequency regulation of the energy storage system is divided into frequency regulation mode and self-recovery mode. The frequency regulation mode of the energy storage system is synchronized with the stable regulation mode of the thermal power unit, and the self-recovery mode of the energy storage system is synchronized with the overshoot mode of the thermal power unit. The thermal power unit and the energy storage system jointly respond to the AGC instruction. When the stable regulation mode of the thermal power unit ends, the thermal power unit output power The output power of the energy storage system is 7MW. Then, the thermal power unit enters the overshoot mode, and the thermal power unit continues to increase at the standard rate. The energy storage system enters the self-recovery mode, and the power of the energy storage system gradually decreases. In the process of the energy storage system power gradually decreasing, the total output power of the thermal power unit and the energy storage system is always 590MW. When the output power of the thermal power unit reaches 590MW, the output power of the energy storage system is zero. Then the output power of the thermal power unit increases at the standard rate. At the end of the overshoot mode, the output power of the thermal power unit is 593MW, of which 3MW is used for self-recovery of the energy storage system capacity.

[0033] Example 2: The rated output power of the thermal power unit is 600MW, the rated output power of the energy storage system is 18MW, the last AGC instruction is 575MW, the current AGC instruction is 560MW, the predicted AGC instruction is 550MW, and the actual output power of the current thermal power unit is 575MW. At this time, the update amplitude of the AGC instruction ΔP A =-15MW, predicting the update amplitude of AGC command ΔP A预 The frequency regulation demand deviation ΔP of the AGC instruction is -10MW, and the SOC of the energy storage system is 3%. According to ΔP A , ΔP A预 , ΔP SOC of energy storage system, P of thermal power unit GCalculate the frequency modulation demand instruction P using other parameters 主 and sub-frequency modulation demand instruction P 次 After receiving the main frequency regulation demand instruction, the thermal power unit responds to the main frequency regulation demand instruction by adjusting the boiler or steam turbine parameters. The frequency regulation of the thermal power unit is divided into stable regulation mode and overshoot mode. After receiving the secondary frequency regulation demand instruction, the energy storage system responds to the secondary frequency regulation demand instruction by controlling the converter parameters. The frequency regulation of the energy storage system is divided into frequency regulation mode and self-recovery mode. The frequency regulation mode of the energy storage system is synchronized with the stable regulation mode of the thermal power unit, and the self-recovery mode of the energy storage system is synchronized with the overshoot mode of the thermal power unit. The thermal power unit and the energy storage system jointly respond to the AGC instruction. When the stable regulation mode of the thermal power unit ends, the output power of the thermal power unit is 568MW, the output power of the energy storage system is -8MW; then, the thermal power unit enters the overshoot mode, the thermal power unit continues to reduce at the standard rate, the energy storage system enters the self-recovery mode, and the power of the energy storage system gradually increases. In the process of the energy storage system power gradually increasing, the total output power of the thermal power unit and the energy storage system is always 560MW. When the output power of the thermal power unit reaches 560MW, the output power of the energy storage system is zero, and then the output power of the thermal power unit is reduced at the standard rate. At the end of the overshoot mode, the output power of the thermal power unit is 557MW, of which 3MW is used for self-recovery of the energy storage system capacity.

[0034] Example 3: The rated output power of the thermal power unit is 600MW, the rated output power of the energy storage system is 18MW, the last AGC instruction is 575MW, the current AGC instruction is 580MW, the predicted AGC instruction is 580MW, and the actual output power of the current thermal power unit is 575MW. At this time, the update amplitude of the AGC instruction ΔP A The update amplitude of the AGC command is 5MW, and the predicted update amplitude ΔP A预 is 0MW, the frequency regulation demand deviation ΔP of the AGC instruction is 5MW, and the SOC of the energy storage system is 50%. According to ΔP A , ΔP A预 , ΔP SOC of energy storage system, P of thermal power unit G Calculate the frequency modulation demand instruction P using other parameters 主 and sub-frequency modulation demand instruction P 次After receiving the main frequency regulation demand instruction, the thermal power unit responds to the main frequency regulation demand instruction by adjusting the boiler or steam turbine parameters. The frequency regulation of the thermal power unit is divided into stable regulation mode and overshoot mode; after receiving the secondary frequency regulation demand instruction, the energy storage system responds to the secondary frequency regulation demand instruction by controlling the converter parameters. The frequency regulation of the energy storage system is divided into frequency regulation mode and self-recovery mode. The frequency regulation mode of the energy storage system is synchronized with the stable regulation mode of the thermal power unit, and the self-recovery mode of the energy storage system is synchronized with the overshoot mode of the thermal power unit; the thermal power unit and the energy storage system jointly respond to the AGC instruction. When the stable regulation mode of the thermal power unit ends, the thermal power unit The output power is 577MW, and the output power of the energy storage system is 3MW; then, the thermal power unit enters the overshoot mode, the thermal power unit continues to increase at the standard rate, the energy storage system enters the self-recovery mode, and the power of the energy storage system gradually decreases. In the process of the energy storage system power gradually decreasing, the total output power of the thermal power unit and the energy storage system is always 580MW. When the output power of the thermal power unit reaches 580MW, the output power of the energy storage system is zero, and then the output power of the thermal power unit remains unchanged. At the end of the overshoot mode, the output power of the thermal power unit is still 580MW, and the energy storage system does not need capacity self-recovery.

[0035] Example 4: The rated output power of the thermal power unit is 600MW, the rated output power of the energy storage system is 18MW, the last AGC instruction is 575MW, the current AGC instruction is 576MW, the predicted AGC instruction is 585MW, and the actual output power of the current thermal power unit is 575MW. At this time, the update amplitude of the AGC instruction ΔP A The update amplitude of the AGC command is 1MW, and the predicted update amplitude ΔP A预 The frequency regulation demand deviation ΔP of the AGC instruction is 9MW, and the SOC of the energy storage system is 30%. According to ΔP A , ΔP A预 , ΔP SOC of energy storage system, P of thermal power unit G Calculate the frequency modulation demand instruction P using other parameters 主 and sub-frequency modulation demand instruction P 次After the thermal power unit receives the main frequency regulation demand instruction, it adjusts the boiler or steam turbine parameters to make the thermal power unit respond to the main frequency regulation demand instruction. The frequency regulation of the thermal power unit is divided into stable regulation mode and overshoot mode. After the energy storage system receives the secondary frequency regulation demand instruction, it responds to the secondary frequency regulation demand instruction by controlling the converter parameters. The frequency regulation of the energy storage system is divided into frequency regulation mode and self-recovery mode. The frequency regulation mode of the energy storage system is synchronized with the stable regulation mode of the thermal power unit, and the self-recovery mode of the energy storage system is synchronized with the overshoot mode of the thermal power unit. The thermal power unit and the energy storage system jointly respond to the AGC instruction. When the stable regulation mode of the thermal power unit ends, the thermal power unit output power The output power of the energy storage system is 1MW. Then, the thermal power unit enters the overshoot mode, and the thermal power unit continues to increase at the standard rate. The energy storage system enters the self-recovery mode, and the power of the energy storage system gradually decreases. In the process of the energy storage system power gradually decreasing, the total output power of the thermal power unit and the energy storage system is always 576MW. When the output power of the thermal power unit reaches 576MW, the output power of the energy storage system is zero. Then the output power of the thermal power unit increases at the standard rate. At the end of the overshoot mode, the output power of the thermal power unit is 578MW, of which 2MW is used for self-recovery of the energy storage system capacity.

[0036] Example 5: The rated output power of the thermal power unit is 600MW, the rated output power of the energy storage system is 18MW, the last AGC instruction is 575MW, the current AGC instruction is 595MW, the predicted AGC instruction is 587MW, and the actual output power of the current thermal power unit is 575MW. At this time, the update amplitude of the AGC instruction is ∆P A For 20MW, the update amplitude of the AGC command is predicted to be ∆P A预 is -8MW, the frequency regulation demand deviation ∆P of the AGC instruction is 20MW, and the SOC of the energy storage system is 80%. According to ∆P A , ΔP A预 , ΔP SOC of energy storage system, P of thermal power unit G Calculate the frequency modulation demand instruction P using other parameters 主 and sub-frequency modulation demand instruction P 次After receiving the main frequency regulation demand instruction, the thermal power unit responds to the main frequency regulation demand instruction by adjusting the boiler or steam turbine parameters. The frequency regulation of the thermal power unit is divided into stable regulation mode and overshoot mode. After receiving the secondary frequency regulation demand instruction, the energy storage system responds to the secondary frequency regulation demand instruction by controlling the converter parameters. The frequency regulation of the energy storage system is divided into frequency regulation mode and self-recovery mode. The frequency regulation mode of the energy storage system is synchronized with the stable regulation mode of the thermal power unit, and the self-recovery mode of the energy storage system is synchronized with the overshoot mode of the thermal power unit. The thermal power unit and the energy storage system jointly respond to the AGC instruction. When the stable regulation mode of the thermal power unit ends, the output power of the thermal power unit is 583MW, the output power of the energy storage system is 12MW; then, the thermal power unit enters the overshoot mode, the thermal power unit continues to increase at the standard rate, the energy storage system enters the self-recovery mode, and the power of the energy storage system gradually decreases. In the process of the energy storage system power gradually decreasing, the total output power of the thermal power unit and the energy storage system is always 595MW. When the output power of the thermal power unit reaches 595MW, the output power of the energy storage system is zero, and then the output power of the thermal power unit decreases at the standard rate. At the end of the overshoot mode, the output power of the thermal power unit is 593MW, of which 2MW is used for self-recovery of the energy storage system capacity.

[0037] While typical embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications and changes can be made within the scope of the claims.

Claims

1. A control method for a thermal power energy storage combined frequency regulation and capacity self-recovery system, characterized in that: The following steps are involved: Step 1: The thermal power unit control system and the energy storage control system respectively receive the AGC instructions issued by the power grid dispatching center through the power plant remote terminal unit, as well as the operating data of the thermal power unit and the energy storage system, and analyze and judge the received data; calculate and predict the AGC instructions based on the received AGC instructions, and calculate the AGC instructions based on the formula ΔP A =P AGC -P AGC-1 Calculate the update range of the current AGC instruction; establish the prediction mechanism of AGC instruction based on the historical database of AGC instruction, and calculate the update range of the current AGC instruction based on the formula ΔP A预 =P AGC预 -P AGC Calculate the update amplitude of the predicted AGC instruction; Set the secondary frequency modulation dead zone P d , P d The value of is less than or equal to 0.3% of the rated power of the thermal power unit; if the absolute value of the update amplitude is less than P d , then it is a microinstruction, if P d ≤Absolute value of update amplitude≤P max , then it is a medium instruction. If the absolute value of the update amplitude is greater than P max , then it is a large instruction; According to the formula ΔP=P AGC -P G , calculate the frequency modulation demand deviation of the current AGC instruction; determine the SOC of the energy storage system; Step 2: The control system of the thermal power unit changes the original control logic that is irrelevant to the parameters of the energy storage system, and changes the control logic according to ΔP A , ΔP A预 , ΔP, SOC of energy storage system, P of thermal power unit G Calculate and send the main frequency regulation demand instruction P to the thermal power unit 主 To achieve main frequency regulation; the thermal power unit control system and the energy storage control system establish a real-time two-way communication mechanism. The thermal power unit control system obtains the SOC of the energy storage system in real time, and the energy storage control system obtains the output power of the thermal power unit in real time. The energy storage control system is based on ΔP A , ΔP A预 , ΔP, SOC of energy storage system, P of thermal power unit G Calculate and send the frequency modulation demand instruction P to the energy storage system 次 , to achieve sub-frequency modulation; Step 3: After receiving the main frequency regulation demand instruction, the thermal power unit adjusts the boiler or steam turbine parameters so that the output power of the thermal power unit responds to the main frequency regulation demand instruction, and sends the generator power to the energy storage control system in real time. At the same time, it receives the SOC and energy storage output power sent by the energy storage control system in real time. The frequency regulation of the thermal power unit is divided into stable regulation mode and overshoot mode. In stable regulation mode, the thermal power unit and the energy storage system jointly output to meet the requirements of the AGC instruction. In overshoot mode, the output of the thermal power unit is maximized while the capacity of the energy storage system is restored. After receiving the secondary frequency regulation demand instruction from the energy storage control system, the energy storage system responds to the secondary frequency regulation demand instruction by controlling the converter parameters. The frequency regulation of the energy storage system is divided into frequency regulation mode and self-recovery mode. Among them, the frequency regulation mode of the energy storage system is synchronized with the stable regulation mode of the thermal power unit, and the self-recovery mode of the energy storage system is synchronized with the overshoot mode of the thermal power unit. Step 4: During the joint frequency regulation of the thermal power generation unit and the energy storage system, the joint frequency regulation of the thermal power generation unit and the energy storage system always meets the frequency regulation requirements of the AGC instruction. At the same time, it ensures that the energy storage system has appropriate two-way frequency regulation capabilities. After executing an AGC instruction, the frequency regulation performance is calculated. In order to quantitatively describe the effect of the joint frequency regulation of the thermal power generation unit and the energy storage system, the frequency regulation performance index M is defined, M= , and set the frequency regulation limit M0 of M. The smaller M is, the smaller the deviation of the thermal power unit and the energy storage system in coordinating the response to the AGC command is, and the better the frequency regulation effect is. When M>M0, repeat steps 1 to 4. When M<M0, the frequency regulation ends. Where ΔP A is the update amplitude of the AGC instruction, P AGC is the current AGC instruction, P AGC-1 is the last AGC instruction, ΔP A预 To predict the update amplitude of AGC instruction, P AGC预 To predict the AGC instruction, ΔP is the frequency modulation requirement deviation of the current AGC instruction, P G It is the real-time output power of the thermal power unit.

2. A control method for a thermal power energy storage combined frequency modulation and capacity self-recovery system according to claim 1, characterized in that: In step 3, the stable regulation mode of the thermal power unit determines the joint frequency regulation mode of the energy storage system and the thermal power unit based on the update amplitude of the AGC instruction and the SOC. When the AGC instruction is a microinstruction, the energy storage system takes priority in the joint frequency regulation, the thermal power unit does not produce power, and the power of the thermal power unit remains unchanged. The output power of the energy storage system is specifically determined based on the SOC until the combined power of the thermal power unit and the energy storage system is equal to the AGC instruction. However, when the output power corresponding to the SOC before the energy storage system responds is 0 or the SOC enters the range of output power 0 during the response process, the thermal power unit responds instead of the energy storage system; when the AGC instruction is a medium instruction, the thermal power unit and the energy storage system respond jointly, and the thermal power unit responds at a reference regulation rate. The value of the reference regulation rate is determined according to the frequency regulation demand deviation of the AGC instruction, and the reference regulation rate is positively correlated with the frequency regulation demand deviation of the AGC instruction. The power of the energy storage system is determined according to different SOCs until the combined power of the thermal power unit and the energy storage system is equal to the AGC instruction; when the AGC instruction is a large instruction, the thermal power unit and the energy storage system respond jointly, and the thermal power unit responds at a high regulation rate. The value of the high regulation rate is determined according to the frequency regulation demand deviation of the AGC instruction, and the high regulation rate is positively correlated with the frequency regulation demand deviation of the AGC instruction. The power of the energy storage system is determined according to different SOCs until the combined power of the thermal power unit and the energy storage system is equal to the AGC instruction.

3. The control method of a thermal power energy storage combined frequency modulation and capacity self-recovery system according to claim 1, characterized in that: In step 3, the output power of the energy storage system is different at different states of charge (SOC), and the capacity is limited. When the SOC is extremely high, the charging power is low, and when the SOC is extremely low, the discharging power is low. This makes the energy storage system under-powered at the extreme SOC value, and limits the system capacity recovery. Therefore, the maximum state of charge (SOC) of the energy storage system is set. max and minimum SOC min , as well as the upper limit SOC1 and lower limit SOC2 of the recovery target, SOC max ≥96%, SOC min ≤4%, 47%≤SOC1≤50%≤SOC2≤53%. When SOC1≤SOC≤SOC2, the energy storage system has bidirectional adjustment capability.

4. The control method of a thermal power energy storage combined frequency modulation and capacity self-recovery system according to claim 1, characterized in that: In step 3, the frequency modulation mode of the energy storage system, the SOC of the energy storage system first determines the output of the energy storage system, and immediately activates the dead zone in the current operating state and outputs the output power in the area corresponding to the SOC. When the output power is positive, the energy storage system discharges, and when the output power is negative, the energy storage system charges; when charging, when SOC≤SOC2, the output power of the energy storage system is -P RB , when SOC2≤SOC≤SOC max When SOC≥SOC, the output power of the energy storage system is a linear function of SOC. The output power decreases as SOC increases. max When SOC≤SOC min When the output power of the energy storage system is 0, when SOC min When SOC≤SOC1, the output power of the energy storage system is a linear function of SOC, and the output power increases with the increase of SOC. When SOC≥SOC1, the output power of the energy storage system is P RB ; SOC1 is the upper limit of the energy storage system's state of charge recovery target, SOC2 is the lower limit of the energy storage system's state of charge recovery target, SOC max The maximum state of charge of the energy storage system, SOC min It is the minimum state of charge of the energy storage system.

5. The control method of a thermal power energy storage combined frequency modulation and capacity self-recovery system according to claim 1, characterized in that: In step 3, when the steady-state mode of the thermal power unit is completed, it enters the overshoot mode. If ΔP A预 With ΔP A If both are greater than zero or both are less than zero, then P AGC预 With P AGC Positive correlation; on the contrary, P AGC预 With P AGC Negative correlation; regardless of ΔP A Is it greater than zero or less than zero? If ΔP A预 is equal to 0, then P AGC预 With P AGC Zero correlation; when P AGC预 With P AGC When the correlation is positive or negative, the overshoot coefficient f ranges from 0.1 to 0.3; when P AGC预 With P AGC When the correlation is zero, the value range of the overshoot coefficient f is 0~0.2; the specific overshoot coefficient is determined according to P AGC预 With P AGC and the SOC determination of the energy storage system.

6. The control method of a thermal power energy storage combined frequency modulation and capacity self-recovery system according to claim 1, characterized in that: In step 3, in overshoot mode, P AGC预 With P AGC Positive or negative correlation, when the thermal power unit just enters the overshoot mode, the SOC of the energy storage system is ≤ SOCmin or SOC ≥ SOC max When 0.25<f<0.3, the SOC of the energy storage system when the thermal power unit just enters the overshoot mode min ≤SOC≤SOC1 or SOC2≤SOC≤SOC max When the thermal power unit just enters the overshoot mode, the energy storage system SOC1≤SOC≤SOC2, 0.1<f<0.15; P AGC预 With P AGC When the thermal power unit just enters the overshoot mode, the energy storage system SOC≤SOC min or SOC ≥ SOC max When 0.15<f<0.2, the SOC of the energy storage system when the thermal power unit just enters the overshoot mode min ≤SOC≤SOC1 or SOC2≤SOC≤SOC max When 0.05<f<0.15, when the thermal power unit just enters the overshoot mode and the energy storage system SOC1≤SOC≤SOC2, f=0; f is the overshoot coefficient, SOC1 is the upper limit of the energy storage system charge state recovery target, SOC2 is the lower limit of the energy storage system charge state recovery target, SOC max The maximum state of charge of the energy storage system, SOC min It is the minimum state of charge of the energy storage system.

7. The control method of a thermal power energy storage combined frequency modulation and capacity self-recovery system according to claim 1, characterized in that: In step 3, when the thermal power unit enters the overshoot mode, the thermal power unit continues to increase or decrease at the standard rate, the energy storage system enters the self-recovery mode, and the output power of the energy storage system gradually decreases or increases. During the process of the energy storage system gradually exiting, the joint frequency regulation of the thermal power unit and the energy storage system always meets the frequency regulation demand instruction P AGC When the output power of the thermal power unit independently meets the frequency regulation demand instruction P AGC After the demand is met, the energy storage system output power is zero, the thermal power unit continues to operate in overshoot mode, and the energy storage system begins to perform capacity self-recovery.

8. The control method of a thermal power energy storage combined frequency regulation and capacity self-recovery system according to claim 1, characterized in that: Furthermore, in step 3, if P AGC预 With P AGC If the actual correlation is different from the predicted correlation, the energy storage system immediately exits the self-recovery mode and enters the regulation mode.

9. The control method of a thermal power energy storage combined frequency modulation and capacity self-recovery system according to claim 1, characterized in that: In step 3, the time it takes for the thermal power unit to complete the steady-state mode and the overshoot mode depends on the regulation rate of the thermal power unit. The baseline regulation rate is set to 1%-1.5% MW / min of the rated power of the thermal power unit, and the high regulation rate is set to 1.5%-2% MW / min of the rated power of the thermal power unit.

10. The control method of a thermal power energy storage combined frequency regulation and capacity self-recovery system according to claim 1, characterized in that: In step 3, the self-recovery mode is based on the overshoot mode of the thermal power unit and is determined according to the SOC of the energy storage system. The self-recovery mode is divided into four modes: strong charge, strong discharge, one-way adaptive, and two-way adaptive. When SOC≤SOC min When SOC≥SOC max When SOC min ≤SOC≤SOC1 or SOC2≤SOC≤SOC max When SOC1≤SOC≤SOC2, the energy storage system is in a unidirectional adaptive mode; when SOC1≤SOC≤SOC2, the energy storage system is in a bidirectional adaptive mode; SOC1 is the upper limit of the energy storage system's state of charge recovery target, SOC2 is the lower limit of the energy storage system's state of charge recovery target, and SOC max The maximum state of charge of the energy storage system, SOC min It is the minimum state of charge of the energy storage system.

11. A control method for a thermal power energy storage combined frequency regulation and capacity self-recovery system according to claim 1, characterized in that: In step 3, in the forced charge or forced discharge mode in the self-recovery mode, while the thermal power unit satisfies the AGC instruction, the overshoot of the thermal power unit prioritizes compensating the energy storage system capacity, so that the SOC of the energy storage system is restored to the SOC corresponding to the unidirectional adaptive mode as soon as possible. When the SOC of the energy storage system changes, the self-recovery mode of the energy storage system is switched accordingly; in the unidirectional adaptive mode in the self-recovery mode, while the thermal power unit satisfies the AGC instruction, the energy storage system capacity is restored at a ratio of not less than 40%; in the bidirectional adaptive mode in the self-recovery mode, the thermal power unit prioritizes satisfying the AGC instruction, and the energy storage system capacity is not restored.

12. A control method for a thermal power energy storage combined frequency regulation and capacity self-recovery system according to claim 1, characterized in that: In step 3, the thermal power unit completes the overshoot capacity corresponding to the overshoot coefficient or the SOC of the energy storage system is in the bidirectional suitable zone. If either of the two conditions is met, the overshoot mode ends.

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