Frequency modulation control optimization method and system based on wind-storage-storage combined system and storage medium

Abstract

The invention relates to the technical field of power system control, in particular to a frequency modulation control optimization method and system based on a wind-storage-storage combined system and a storage medium. On one hand, a rotor kinetic energy strategy is adopted to control a fan system to perform frequency modulation so as to provide frequency support, an energy storage battery compensates power reduction caused by a water hammer effect of pumped storage and supports fan rotating speed recovery, and complementary advantages of wind storage resources are achieved; and on the other hand, the same-direction dead zone difference value existing between the actual output of the thermal power system and the automatic power generation control instruction is overcome through cooperative power compensation of the pumped storage system and the energy storage system. The problem of how to improve the frequency stability of a power system is solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of power system control, in particular to a frequency modulation control optimization method and system based on a wind-pumped-storage combined system and a storage medium. BACKGROUND

[0002] With the transformation of global energy structure, wind energy, as one of the most potential new energies, is increasingly valued in development and utilization. However, the strong randomness and volatility of wind power output bring great challenges to the frequency stability of the power system. In related technical solutions, pumped storage and energy storage batteries are introduced as energy storage supporting of wind energy, which can effectively improve the consumption rate of wind power in the new power system.

[0003] However, current wind farm frequency modulation control strategies mainly focus on the utilization of single resource, and lack of collaborative optimization of wind, pumped storage and energy storage. Traditional wind farm modeling methods are difficult to improve simulation efficiency while ensuring accuracy, which limits the frequency modulation performance evaluation of large-scale wind farms. In addition, there is still optimization space for model construction and control strategy design of pumped storage units and energy storage batteries when participating in frequency modulation.

[0004] In view of this, the application provides a frequency modulation control optimization method based on a wind-pumped-storage combined system, which realizes collaborative optimization of multiple frequency modulation resources through joint frequency modulation of wind, pumped storage and energy storage systems, and improves the frequency stability of the power system. SUMMARY

[0005] The main purpose of the application is to provide a frequency modulation control optimization method based on a wind-pumped-storage combined system, which aims to solve the problem of how to improve the frequency stability of the power system.

[0006] To achieve the above purpose, the application provides a frequency modulation control optimization method based on a wind-pumped-storage combined system, which comprises the following steps: S10, when water hammer effect occurs in the pumped storage system, a rotor kinetic energy strategy is used to control the wind turbine system for frequency modulation, and the energy storage system is controlled for power compensation when the output power of the wind turbine system decreases; S20, the same direction dead zone difference between the actual output of the thermal power system and the automatic generation control instruction is determined, and the pumped storage system and the energy storage system are controlled to collaboratively compensate the power meeting the same direction dead zone difference.

[0007] Optionally, in the S10, the step of using the rotor kinetic energy strategy to control the wind turbine system for frequency modulation comprises the following steps: S11, the frequency change rate and the frequency deviation of the wind turbine system are obtained; S12, determining a target frequency modulation power increment of the wind turbine system according to the frequency change rate and the frequency deviation, wherein a calculation expression of the target frequency modulation power is: wherein, is a target frequency modulation power increment of the wind turbine primary frequency modulation; and is a frequency change rate; is a virtual inertia coefficient, is a droop coefficient; S13, controlling the wind turbine system to perform frequency modulation based on the target frequency modulation power increment.

[0008] Optionally, the virtual inertia coefficient and the droop coefficient are adjusted according to the frequency change rate. wherein the adjusted virtual inertia parameter satisfies the following expression:

[0009] wherein the time constant T is proportional to the output power under virtual inertia control and the frequency modulation exit time, and s is a Laplace operator; wherein the adjusted droop parameter K 2,1 satisfies the following expression:

[0010] wherein t is a current simulation time, t re is a wind turbine frequency modulation exit time, and k c is a parameter of a control change rate.

[0011] Optionally, in the S10, the step of controlling the energy storage system to perform power compensation comprises: S14, calculating a current water hammer output compensation power required by the energy storage system for compensation: wherein TB is an energy storage converter constant; , is a self-adjusted energy storage fast compensation coefficient according to an operating state, and is used to accurately offset the pumped storage power reverse adjustment; represents a first-order inertia link energy storage converter dynamics; S15, calculating an energy storage support power required by the energy storage system for compensation: wherein, is an energy storage additional coefficient, is a rated power of the wind turbine system, is the real-time power of the fan system; is the rated power of the energy storage system; wherein: wherein: is the slope of the Logistic curve, is the center point of the Logistic curve, is the maximum value of the energy storage additional coefficient; S16, the current water hammer output compensation power is added to the energy storage support power , as the total power compensation power of the energy storage system :

[0012] S17, the energy storage system is controlled to perform power compensation based on the total power compensation power .

[0013] Optionally, the energy storage rapid compensation coefficient satisfies: wherein, represents an energy storage reference compensation coefficient, used to adjust the water hammer effect compensation intensity; represents the angular velocity of the fan rotor; If the frequency of the doubly-fed asynchronous wind power generator after exiting frequency modulation still does not meet the frequency requirement, a new energy storage droop rapid compensation coefficient K B2,1 satisfies; The energy storage support power satisfies:

[0014] wherein:

[0015] .

[0016] Optionally, the S20 specifically includes: S21, determining the current stage of the thermal power system, the current stage including one of a response stage, a climbing stage and a stable stage; S22, determining the target compensation strategy of the pumped storage system and the energy storage system according to the current stage of the thermal power system; S23, control the pumped storage system and the energy storage system to compensate for the power meeting the same-direction dead-zone difference according to the same-direction dead-zone difference.

[0017] Optionally, the target compensation strategy comprises: S221, when the thermal power system is in a response stage, control the pumped storage system and the energy storage system to compensate for a first power meeting the same-direction dead-zone difference : ΔP pump (t) is the power deviation of the pumped storage unit at time t; ΔP bcss (t) is the power deviation of the energy storage battery at time t; S222, when the thermal power system is in a climbing stage, determine the power distribution ratio of the pumped storage system and the energy storage system according to the available frequency modulation capacity of the pumped storage system and the energy storage system, control the pumped storage system and the energy storage system to compensate for a second power meeting the same-direction dead-zone difference : α、 are both power distribution ratios, ΔP is the power deviation of the pumped storage system at time t, is the power deviation of the energy storage system at time t; ΔP is the available frequency modulation capacity of the pumped storage system at time t; is the remaining frequency modulation capacity of the energy storage system; S223, when the thermal power system is in a stable stage, optimize the processing distribution of the pumped storage system and the energy storage system with the target of minimizing the steady-state frequency deviation.

[0018] Optionally, in the S223, the step of optimizing the processing distribution of the pumped storage system and the energy storage system with the target of minimizing the steady-state frequency deviation comprises: S2231, determine the steady-state frequency deviation in the pumped storage system and the energy storage system : Wherein, Δf1(t) and Δf2(t) are the steady-state frequency deviation of the dead zone and the linear response zone at time t, respectively. S2232, determining the frequency deviation determining the smooth output of the energy storage system : Wherein, K droop is the energy storage droop coefficient; S2233, determining the smooth output of the energy storage system calculating the support output of the pumped storage system : Wherein, the frequency deviation coefficient; the generator droop coefficient; is the system load change; S2234, controlling the energy storage system to perform power compensation based on the smooth output and controlling the pumped storage system to perform power compensation based on the support output.

[0019] In addition, to achieve the above object, the present application also provides a computer system, comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the frequency control optimization method based on the wind-pumped-storage combined system according to any one of the above.

[0020] In addition, to achieve the above object, the present application also provides a computer readable storage medium, wherein the computer readable storage medium stores a computer program, and the computer program, when executed by a processor, implements the steps of the frequency control optimization method based on the wind-pumped-storage combined system according to any one of the above.

[0021] The present application has at least the following beneficial effects: 1. The rotor kinetic energy strategy is used to control the wind turbine system to provide frequency support, and the energy storage battery compensates for the power reduction of the pumped storage due to the water hammer effect and supports the recovery of the wind turbine speed, so as to realize the complementary advantages of wind storage resources; 2. The problem of the same direction dead zone difference between the actual output and the automatic generation control instruction of the thermal power system is overcome by the collaborative power compensation of the pumped storage system and the energy storage system; 3. The frequency regulation burden of the thermal power system is reduced through the collaborative frequency regulation of wind-pumped-storage; BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 ​A flowchart of a first embodiment of the frequency control optimization method based on a wind-pumped-storage combined system according to the embodiments of the present application; Figure 2 A water turbine water hammer effect diagram according to the embodiments of the present application; Figure 3 A fan double-mode frequency modulation model diagram according to the embodiments of the present application; Figure 4 A structure diagram of a water pump turbine simulation model according to the embodiments of the present application; Figure 5 An equivalent circuit diagram of a lead-carbon battery according to the embodiments of the present application; Figure 6 A lead-carbon battery control circuit diagram according to the embodiments of the present application; Figure 7 A simulation diagram of equivalent wind turbine cooperative energy storage primary frequency modulation according to the embodiments of the present application; Figure 8 A wind speed scene at a certain moment and equivalent wind speed distribution diagram of each group according to the embodiments of the present application; Figure 9 System frequency response diagrams of different control strategies according to the embodiments of the present application; Figure 10 Output power diagrams of each group according to the embodiments of the present application; Figure 11 Output power diagrams of energy storage according to the embodiments of the present application; Figure 12 A combined system three-region frequency control model diagram according to the embodiments of the present application; Figure 13 Secondary frequency modulation comparison diagrams in three cases according to the embodiments of the present application; Figure 14 Transient and steady state frequency deviation comparison diagrams in three cases according to the embodiments of the present application; Figure 15 Region i pumped storage and thermal power system output diagrams according to the embodiments of the present application; Figure 16 Region i energy storage response AGC output diagrams according to the embodiments of the present application; Figure 17 An architecture diagram of a hardware running environment of a computer system according to the embodiments of the present application; The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0023] For a better understanding of the above technical solutions, the exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be accurately conveyed to those skilled in the art.

[0024] First embodiment With reference to Figure 1 , the present embodiment provides a frequency control optimization method based on a wind-pumped storage combined system, which is applied to a hybrid power generation system including a wind turbine system, a pumped storage system, an energy storage system and a thermal power system, and specifically includes the following steps: S10, when detecting that the water hammer effect occurs in the pumped storage system, the rotor kinetic energy strategy is used to control the wind turbine system to perform frequency regulation, and the energy storage system is controlled to perform power compensation when the output power of the wind turbine system decreases; In this embodiment, when the water hammer effect occurs, with reference to Figure 2 The water hammer effect of the water turbine is shown in the schematic diagram, which is mainly caused by the inertia of water flow in the pipe. It is shown that the change of water flow of the water turbine lags behind the change of the guide vane opening. When the guide vane is opened, although the expected flow increases, the instantaneous pipe pressure drop will cause the output power to decrease temporarily rather than immediately increase, forming a reverse regulation, i.e. water hammer phenomenon. This effect is more significant in the pump-turbine model with a water diversion system. The pipe length and structural characteristics of the water diversion system will exacerbate the inertia and hysteresis of the water flow.

[0025] In some optional embodiments, for how to detect the water hammer effect in the pumped storage system, the following methods can be used: The water hammer effect detection controller analyzes the primary frequency regulation response of the pumped storage unit after a small load disturbance, and uses the pump-turbine speed deviation ∆ω pump and the mechanical power deviation ∆P m_pump Design a controller that can detect water hammer effect. When ∆ω pump and ∆P m_pump have the same sign, water hammer effect occurs; when ∆ω pump and mechanical power deviation ∆P m_pump have opposite signs, it is considered that there is no water hammer effect, Exemplarily, the water hammer effect is detected as follows: When the water hammer effect occurs, the hybrid power generation system first compensates power based on the designed hybrid frequency modulation strategy of the fan-energy storage, in primary frequency modulation, the fan releases the rotor kinetic energy to provide frequency support, and the energy storage battery compensates the water hammer effect of pumped storage and supports the recovery of the fan speed, realizing the complementary advantages of wind storage resources.

[0026] Further and optionally, the rotor kinetic energy strategy is used to control the frequency modulation of the fan system. The rotor kinetic energy control utilizes the rotational kinetic energy of the fan rotor for rapid frequency modulation, including virtual inertia control and droop control. The virtual inertia control simulates the inertia of a synchronous generator and adjusts the active output according to the frequency change rate; the droop control adjusts the active output according to the frequency deviation, and the combination of the two forms a comprehensive inertia control, achieving a more optimal frequency modulation effect. The specific steps are as follows: S11, obtaining the frequency change rate and frequency deviation of the fan system; S12, determining the target frequency modulation power increment of the fan system according to the frequency change rate and the frequency deviation, wherein the calculation expression of the target frequency modulation power is: In the formula, is the target frequency modulation power increment of the fan primary frequency modulation; Δf is the system frequency deviation; is the frequency change rate; is the virtual inertia coefficient, is the droop coefficient; S13, controlling the fan system to modulate frequency based on the target frequency modulation power increment.

[0027] In this step, considering that the power output of the DFIG (Doubly fed Induction Generator, doubly fed induction generator) in the fan system gradually decreases under the droop control in the speed recovery stage, its speed starts to recover. To prevent the frequency from falling again during this process, the energy storage system needs to intervene in time to make up for the reduced power output of the DFIG when it exits frequency modulation.

[0028] Further and optionally, the step of controlling the energy storage system to compensate power comprises: S14, calculating the current water hammer output compensation power TB required by the energy storage system : In the formula, TB is the energy storage converter constant; 、 is the self-adjusting energy storage fast compensation coefficient according to the operating state, which is used to accurately offset the anti-regulation of pumped storage power; represents the first-order inertia link energy storage converter dynamics; S15, calculating required compensation energy storage support power of the energy storage system : wherein, is an energy storage additional coefficient, is rated power of the fan system, is real-time power of the fan system; is rated power of the energy storage system; wherein: wherein; is a slope of the Logistic curve, is a center point of the Logistic curve, is a maximum value of the energy storage additional coefficient; S16, taking a sum of the current water hammer output compensation power and the energy storage support power as total power compensation power of the energy storage system :

[0029] S17, controlling the energy storage system to perform power compensation based on the total power compensation power .

[0030] S20, determining a same-direction dead zone difference value between actual output of the thermal power system and an automatic generation control instruction, and controlling the pumped storage system and the energy storage system to cooperatively compensate power meeting the same-direction dead zone difference value.

[0031] In the embodiment, when the frequency modulation scheduling instruction changes, the thermal power system in the hybrid power generation system enters a new examination stage, and adjusts power with the instruction as a target. However, due to the limitation of its own technical characteristics, the actual output of the thermal power system has a large difference with the same-direction AGC (Automatic Generation Control) instruction dead zone. To solve this problem, the embodiment proposes to use pumped storage and energy storage batteries to assist the secondary frequency modulation of the thermal power system, thereby improving the frequency modulation performance of the system.

[0032] Further and optionally, to realize the optimal power distribution of the pumped storage unit and the energy storage battery in the secondary frequency modulation process, the embodiment further provides a power distribution strategy, which divides the thermal power system into a response stage, a climbing stage and a stable stage. The S20 specifically includes: S21, determining a current stage of the thermal power system, the current stage including one of a response stage, a climbing stage and a stable stage; S22, determining a target compensation strategy of the pumped storage system and the energy storage system according to a current stage of the thermal power system; S23, controlling the pumped storage system and the energy storage system to compensate power satisfying the same-direction dead zone difference according to the target compensation strategy according to the same-direction dead zone difference.

[0033] In the technical scheme provided in the embodiment, when the water hammer effect occurs, the rotor kinetic energy strategy is used to control the fan system to provide frequency support, the energy storage battery compensates for the power reduction of the pumped storage due to the water hammer effect and supports the recovery of the fan speed, and the complementary advantages of the wind storage resources are realized; on the other hand, the problem of the same-direction dead zone difference between the actual output of the thermal power system and the automatic generation control instruction is overcome by the coordinated power compensation of the pumped storage system and the energy storage system.

[0034] Second embodiment Based on the technical scheme in the first embodiment, in the traditional comprehensive inertia control, the virtual inertia control and the droop control jointly act on the wind turbine to provide frequency support, however, in order to further optimize the control effect, especially to reduce the influence of frequency secondary drop, the embodiment provides a method for improving the parameters of the comprehensive inertia control, as follows: 1) Improvement of virtual inertia control parameters The traditional virtual inertia control simulates the inertia response of the synchronous generator by introducing the frequency change rate (dΔf / dt). In order to smooth the energy release process and avoid impact on the system near the frequency minimum point, the present application introduces a first-order inertia link before the virtual inertia control parameter K1, and obtains a new virtual inertia control parameter K 1,1 : Wherein, T is the time constant, and s is the Laplace operator.

[0035] The new virtual inertia control power is: 2) Improvement of droop control parameters In the frequency recovery stage, in order to avoid the fan from exiting frequency modulation due to long-term low-speed operation, and at the same time to reduce the influence of frequency secondary drop, the present application dynamically adjusts the droop control parameters. The Logistic function is introduced to make the droop control parameters change smoothly with time: Wherein, k c is the control change rate parameter, and t c is the center point.

[0036] The new droop control power is: 3) Comprehensive inertia control after improving parameters The total frequency modulation active power of the DFIG obtained by the improved virtual inertia control and droop control is: In the initial frequency modulation stage, the virtual inertia control and the droop control jointly provide frequency support; as the frequency recovers, the virtual inertia control gradually weakens to zero to avoid frequency fluctuations caused by absorbing energy from the power grid; and the droop control automatically exits the frequency modulation according to the change law of the Logistic function, reducing the risk of secondary frequency drop.

[0037] Third embodiment Based on any of the above embodiments, the present embodiment provides a specific construction method of the target compensation strategy, which is as follows: (1) Establish a two-region load frequency control model In order to accurately simulate the dynamic behavior of a multi-region power system in the secondary frequency modulation process, the present application establishes a two-region load frequency control model including a pumped storage model and an energy storage model of generation and pumping conditions. The model adopts a tie-line frequency bias control (TBC) mode, and the calculation formula of the area control error (ACE) thereof is: Wherein: B i is the frequency deviation coefficient of region i, indicating the sensitivity of the region to frequency deviation; Δf i (t) is the frequency deviation of region i at time t; T ij is the synchronization power coefficient between region i and region j, indicating the power transmission efficiency of the tie-line between the two regions; ΔP tie,ij (t) is the tie-line power deviation between region i and region j at time t.

[0038] Through the TBC mode, the model can more comprehensively reflect the influence of power exchange between regions on system frequency.

[0039] (2) Pumped-storage coordination control unit design 1. Response stage The frequency modulation response stage of the thermal power system starts at the AGC command update time. The configuration of pumped storage can quickly make up for the same direction dead zone difference between the thermal power system output and the AGC command. The goal of this stage is to cross the dead zone of the fire-pumped-storage-battery joint output, so the total power command that pumped storage and energy storage batteries need to respond at time t is:

[0040] when discharging​ , charging time .

[0041] 2. Climbing stage The addition of pumped storage and energy storage batteries makes the frequency modulation response stage of the thermal power system very short, and it can be considered that the AGC command update time enters the climbing stage. The target is: 1) Monitor the combined output of fire-pumped storage-energy storage to avoid falling into the same direction dead zone of AGC command and extend the response stage; 2) Real-time monitoring of the difference between the thermal power system and the AGC command dead zone, and only when the total power of the pumped storage and energy storage is completely compensated for the difference, adjust the power deviation, end the climbing stage, and enter the stable stage.

[0042] Climbing stage, the difference between the actual output of the thermal power system and the same direction AGC command dead zone at time T1 is:

[0043] 3. Stable stage The signal for the thermal power system to enter the frequency modulation stable stage is that the combined output of fire-pumped storage-energy storage crosses the dead zone in the same direction as the AGC command. The control target of the pumped storage and energy storage in this period is to minimize the deviation between and , and the power command of the pumped storage and energy storage is:

[0044] (3) Formulation of target compensation strategy In order to realize the optimal power distribution of pumped storage units and energy storage batteries in the secondary frequency modulation process, the application designs a detailed power distribution strategy, including the response stage, the climbing stage and the stable stage.

[0045] In the response stage, the coordination control unit first calculates the same direction dead zone difference between the thermal power system and the AGC command: Wherein: ΔP AGC (t) is the power deviation of the AGC command at time t; ΔP deadband is the dead zone power deviation of the thermal power system.

[0046] Then, the coordination control unit starts the pumped storage unit and the energy storage battery, and quickly compensates for the frequency modulation deficiency of the thermal power system by quickly adjusting the output thereof: Wherein: ΔP pump (t) is the power deviation of the pumped storage unit at time t; ΔP bess (t) is the power deviation of the energy storage battery at time t.

[0047] In the climbing stage, the coordination control unit monitors the power deviation between the actual output of the thermal power system and the AGC instruction in real time, and dynamically adjusts the power distribution ratio between the pumped storage unit and the energy storage battery according to the frequency modulation capacity of the two: Wherein: α (t) is the dynamic allocation coefficient, indicating the proportion of the pumped storage unit in the total power deviation; ΔP pump,cap (t) is the available frequency modulation capacity of the pumped storage unit at time t; ΔP bess,cap (t) is the available frequency modulation capacity of the energy storage battery at time t; ΔP error (t) is the power deviation between the thermal power system and the AGC instruction.

[0048] In the stable stage, the main goal of the coordination control unit is to minimize the steady-state frequency deviation, at this time, the coordination control unit will optimize the output distribution of the pumped storage unit and the energy storage battery according to the current state of the two, to minimize the steady-state frequency deviation: Wherein, Δf1 (t) and Δf2 (t) are the steady-state frequency deviations of the dead zone and the linear response zone at time t, respectively.

[0049] Energy storage smooth output: In the formula, K droop is the energy storage droop coefficient Pumped storage provides base value support: In the formula, Frequency deviation coefficient; Generator regulation coefficient; is the system load change.

[0050] The above process is described in the form of steps, and the model construction and unit design part is omitted, that is: S221, when the thermal power system is in the response stage, controlling the pumped storage system and the energy storage system to cooperatively compensate the first power : In the formula, ΔP pump (t) is the power deviation of the pumped storage unit at time t; ΔP bcss (t) is the power deviation of the energy storage battery at time t; S222, when the thermal power system is in a climbing stage, determining a power distribution ratio of the pumped storage system and the energy storage system according to available frequency modulation capacities of the pumped storage system and the energy storage system, and controlling the pumped storage system and the energy storage system to compensate for a second power satisfying the same-direction dead-band difference according to the respective power distribution ratios : wherein α, are power distribution ratios, is a power deviation of the pumped storage system at time t, is a power deviation of the energy storage system at time t; wherein a calculation expression of the power distribution ratio is wherein is an available frequency modulation capacity of the pumped storage system at time t; is a remaining frequency modulation capacity of the energy storage system; S223, when the thermal power system is in a stable stage, optimizing a power distribution of the pumped storage system and the energy storage system with a target of minimizing a steady-state frequency deviation.

[0051] wherein S223 includes: S2231, determining a steady-state frequency deviation of the pumped storage system and the energy storage system : wherein Δf1(t) and Δf2(t) are steady-state frequency deviations of the dead-band and the linear response region at time t, respectively; S2232, determining a smoothing output of the energy storage system according to the steady-state frequency deviation : wherein K droop is an energy storage droop coefficient; S2233, calculating a support output of the pumped storage system according to the smoothing output of the energy storage system : wherein is a frequency deviation coefficient; is a generator droop coefficient; is a system load change amount; S2234, controlling the energy storage system to compensate for a third power satisfying the same-direction dead-band difference based on the smoothing output of the energy storage system ​​performing power compensation, and controlling the pumped hydro storage system to provide support power based on the support power performing power compensation.

[0052] Fourth embodiment Based on any of the above embodiments, in this embodiment, a wind turbine dual-mode frequency modulation model of a hybrid power generation system is provided. The model realizes power backup through overspeed tripping and variable pitch control, and forms a rotor kinetic energy comprehensive frequency modulation strategy combining virtual inertia control and droop control. The power backup control is as follows: The power backup control reserves part of the active power to support system frequency modulation, mainly including overspeed tripping control and variable pitch control.

[0053] Overspeed tripping control: by increasing the rotor speed, the DFIG operates at a suboptimal power point, and part of the power is reserved for frequency modulation.

[0054] Active power output by the DFIG in the tripping mode: In the formula, PMPPT is the active power output by the wind turbine in the MPPT mode; Cp,de is the wind energy utilization coefficient in the tripping mode; Power tracking coefficient in the tripping mode.

[0055] Variable pitch control: by adjusting the pitch angle, the aerodynamic characteristics of the wind turbine are changed, and part of the power is reserved for frequency modulation.

[0056] Actual pitch angle:

[0057] In the formula, P is the pitch angle reference value; is the pitch angle adjustment coefficient, is the pitch angle adjustment coefficient.

[0058] Fifth embodiment Based on any of the above embodiments, in this embodiment, a mathematical model of a pumped hydro storage system in a hybrid power generation system is provided. The model includes detailed mathematical models of the pump-turbine model, the governor and servo system model. The specific implementation is as follows: 1. Pump-turbine model: The pump-turbine model of the water diversion system describes the flow characteristics of water flow in the pipeline and the conversion efficiency of the water turbine blades to the water flow. Its mathematical expression can be expressed as: Where Q is the flow rate, D is the pipe diameter, g is the acceleration due to gravity, H is the water head, p is the density of water, and h is the efficiency of the water turbine.

[0059] 2. Governor and servo system model: The governor and servo system model is used to describe the response speed and control accuracy of the pumped storage unit to the frequency change of the power grid. The governor usually adopts a PID controller, and its transfer function can be represented as:

[0060] Where Kp, Ki, and Kd are the proportional, integral, and derivative coefficients, respectively, and s is the Laplace variable. p , K i , K d are the proportional, integral, and derivative coefficients, respectively, and s is the Laplace variable.

[0061] Step 2.2, establish a water hammer effect model and analyze the influence of water hammer effect on the frequency regulation performance of the pumped storage unit.

[0062] When the pumped storage unit rapidly adjusts the output, due to the existence of water flow inertia, water hammer effect will occur, causing the unit output to change in the opposite direction in a short time, affecting the frequency regulation performance. In order to analyze the influence of water hammer effect, the application introduces a water hammer effect detection controller.

[0063] The mathematical description of water hammer effect can be simplified as an inertia link, and its transfer function can be represented as: Where Tw is the time constant of water hammer effect.

[0064] The pumped storage unit is affected by water hammer effect at the initial stage of frequency regulation, which will cause power reverse regulation phenomenon, aggravate the system power gap and worsen the frequency regulation effect. This application proposes to identify the water flow inertia time constant based on working condition information, estimate the power disturbance combined with the rotor motion equation, and predict the unit output using the simplified governor model to determine the maximum value of power reverse regulation. Through this method, the influence of water hammer effect on the frequency regulation performance of the pumped storage unit can be accurately analyzed, and a theoretical basis is provided for optimizing the frequency regulation control strategy to suppress power reverse regulation and improve the frequency regulation effect.

[0065] Sixth embodiment Based on any of the above embodiments, this embodiment provides a mathematical model of an energy storage system in a hybrid power generation system, including a battery pack, a battery management system (BMS), a power conversion system (PCS), and an LC filter part.

[0066] (1) Battery pack model: The battery pack is the core part of the energy storage system, and its mathematical model can be simplified as an equivalent circuit, including parameters such as the internal resistance, open circuit voltage, and capacitance of the battery. The output voltage Vbat of the battery can be represented as: Where Eoc is the battery's open-circuit voltage, Ibat is the battery's output current, and Rint is the battery's internal resistance.

[0067] (2) SOC dynamic model State of charge (SOC) is calculated by integrating charge and discharge power: In the formula, η lc E represents the charge / discharge efficiency (taken as 1). N For rated capacity, P lc (t) represents instantaneous power (positive for discharging and negative for charging).

[0068] (3) Power Conversion System (PCS) Model The bidirectional DC / AC converter is dynamically simplified to an inertial element: Among them, T conv P is the time constant. ref This is the reference power.

[0069] (4) LC filter: LC filters are used to suppress harmonic currents generated by PCS (Power Control System) and improve power quality. Their mathematical model can be represented as a second-order system with the following transfer function: Among them, L lc For the filter inductor, C dc_lc These are inductors and capacitors.

[0070] In addition, this embodiment also establishes a dynamic SOC model and sets charge and discharge limits to analyze changes in battery state of charge and prevent overcharging / over-discharging.

[0071] (5) SOC dynamic model In the formula: SOC(t) is the state of charge of the battery at time t; EN is the constant energy of the stored energy; η lc τ represents the efficiency of the charging / discharging circuit; P(τ) represents the energy storage power at any given time.

[0072] (6) Charge and discharge limiting Dynamic charging and discharging power limiting. Automatic derating when the state of charge (SOC) approaches the safe limit to prevent overcharging / over-discharging.

[0073] In the formula: P lc,lim SOC rate; P max / Pmin Maximum discharge / charge rate; SOCmin / max SOC lower / upper limit, △f db Energy storage frequency dead zone threshold.

[0074] Seventh embodiment Based on any of the above embodiments, this embodiment provides a simulation model, and verification of the simulation results. Referring to Figure 3 The fan dual-mode frequency modulation model diagram shown, the control strategy of the fan, including a variety of control block diagram and mode fan overspeed relief control block diagram, P refd represent the active power reference value under overspeed relief control; the fan variable pitch angle control block diagram also contains it.

[0075] In terms of virtual inertia control, d / dt is the differential element, but the differential element will amplify the high-frequency fluctuations in the frequency change rate. To avoid this problem, a low-pass filter is connected in series after the differential element, and then multiplied by the inertia gain K d , thus obtaining the active power ΔP d that the rotor-side converter active power given value.

[0076] In addition, Figure 3 The droop control block diagram is also shown in the above. Virtual inertia control and droop control each have their own characteristics. Virtual inertia control will stop providing active power or even absorbing energy after the frequency reaches the lowest point, and its response time is short; while droop control has a relatively slow response, but can continuously increase active output as the frequency changes.

[0077] Given the complementary advantages of the two, virtual inertia control and droop control are often used in combination. This combination forms a control strategy called comprehensive inertia control, which is also reflected in the figure, where ΔP1 and ΔP2 are the virtual inertia control power and droop control power in comprehensive inertia control, respectively.

[0078] Further, referring to Figure 4 The structure diagram of the pump-turbine simulation model shown, ω pump_ref is the pump-turbine speed reference value; ω pump is the actual operating speed of the pump-turbine; Δμ is the adjustment amount output by the speed regulator; Δγ is the guide vane opening change amount of the turbine; ΔP m_pump is the mechanical power change amount of the pump-storage reversible pump-turbine.

[0079] In addition, a multi-level model of energy storage batteries is designed to integrate frequency dead zone and SOC dynamic protection mechanisms to constrain charging and discharging power to ensure frequency modulation safety. The charging and discharging operation of the energy storage device is subject to the state of charge (State of Charge, SOC) of the battery. Referring to Figure 5 The equivalent circuit of lead-carbon battery shown, and the voltage and the current at the output terminals of the battery; U oc_lc is the open circuit voltage when the lead-carbon battery is in a no-load state (I lc = 0); R p , C p are the electrochemical polarization resistance and capacitance; C b is a capacitance that together with U oc_lc simulates the open circuit voltage; R0 is the ohmic internal resistance; U b is the terminal voltage of C b ; U p is the terminal voltage of R p and C p ; U0 is the terminal voltage of R0.

[0080] The lead-carbon battery is connected in series with a controlled voltage source E lc and an internal resistance R lc , and its simplified control circuit diagram is shown in Figure 6 .

[0081] To ensure that the DFIG can effectively assist the system in primary frequency regulation under different operating states, and that the pumped storage unit can compensate for the water hammer effect through wind storage cooperation, thereby fully exerting its ability to participate in secondary frequency regulation, the corresponding control strategy is designed for the system according to the operating state of the DFIG and the influence of the water hammer effect of the pumped storage unit, to meet the needs of different working conditions, Working condition 1: When the grid frequency is not lower than 49.98 Hz, the DFIG (doubly-fed induction generator) and the pumped storage unit are normally operated. If it is detected that the SOC (state of charge) of the energy storage device is at a low level, the charging process is started to restore the SOC, ensuring that the energy storage system has the ability to regulate the frequency at any time.

[0082] Working condition 2: When the grid frequency is lower than 49.98 Hz but not lower than 49.95 Hz, select part of the DFIG group that meets the conditions, and use the comprehensive inertia control strategy to participate in primary frequency regulation. If the DFIG cannot continue to regulate the frequency due to the convergence of the speed, and the current frequency performance is still up to standard, the maximum wind energy control mode is converted to maximize the utilization of wind energy; if the frequency performance is not up to standard, the energy storage system is used as a backup capacity to assist in frequency regulation, ensuring the stability of the grid frequency.

[0083] Case 3: When the grid frequency is lower than 49.95 Hz, first, the water hammer effect detection controller judges whether the pumped storage unit has occurred water hammer effect. If no water hammer effect occurs, the DFIG group uses power reserve and rotor kinetic energy control strategies to fully participate in frequency regulation according to the pre-grouping and parameter equivalent calculation results (equivalent speed and equivalent electromagnetic power). If the frequency regulation effect is still not up to standard, the energy storage system generates additional power to further stabilize the frequency. If water hammer effect is detected, the wind storage collaborative frequency regulation mechanism is immediately started, and the energy storage system and DFIG group double compensate the impact of water hammer effect on the grid, and the energy storage system continuously generates additional power to assist frequency regulation during the process of restoring the wind turbine speed.

[0084] Based on the actual operation data and characteristic analysis of wind turbine generators, parameter equivalent calculation is performed on different groups, and equivalent speed and equivalent electromagnetic power are extracted as key judgment criteria. Through these two parameters, the working area of the equivalent wind turbine model can be determined, and then the adequacy of the frequency regulation resources of each group can be evaluated. According to the evaluation results, appropriate control strategies are selected for different groups, such as comprehensive inertia control, power reserve control, rotor kinetic energy control, etc., to ensure that the wind turbine group can effectively participate in system frequency regulation and improve the frequency stability and reliability of the entire power system.

[0085] To verify the advantages of the frequency regulation control strategy proposed in this application, a simulation model of wind turbine group participating in primary frequency regulation in cooperation with energy storage is constructed on the Matlab / Simulink simulation platform, as shown in Figure 7 In this model, for equivalent groups in different operating states, corresponding control strategies are used.

[0086] Specifically, the equivalent wind speed of the four wind turbine groups is shown in Figure 8 (b). To comprehensively evaluate the performance of the proposed control strategy, a typical scenario of load surge is used for simulation analysis. In the simulation system, the rated frequency is set to 50 Hz, the rated voltage of the outgoing line is 230 kV, and the total installed capacity of the wind farm is 75 MW. Among them, the rated capacity of the thermal power system G1 is 100 MW; the rated capacity of the pumped storage unit G2 is also 100 MW; the installed capacity of the energy storage system is 4 MW, and the rated power is 0.8 MW. The system carries loads of load1 (117 MW), load2 (37.5 MW), load3 (26.5 MW), and load4 (95 MW), in addition, load5 (25 MW) is connected at 50s as a disturbance load to verify the effectiveness of the proposed strategy.

[0087] Taking load surge as an example, the control strategy is shown in Table 1: Table 1 Control strategy

[0088] The simulation results are shown in FIGS. 1-3, and the results shown in Table 2 are obtained, where the frequency change rate RoCoF is defined as the average change rate during the period from the frequency starting to drop (the initial frequency is set to the nominal value 50 Hz) to the lowest point of the frequency: Figure 9 Figure 10 Table 2 Comparison of system frequency modulation data under different control strategies

[0089] Since the pumped storage unit mainly acts on the secondary frequency modulation, the influence of pumped storage on primary frequency modulation can be ignored. As shown in FIG. 4, the frequency modulation effects under different control strategies show significant differences: Figure 11 (1) By comparing the primary frequency modulation effects of strategy one and strategy two, it can be verified that the water hammer effect of pumped storage has an influence on the frequency modulation performance. In the case where strategy one does not compensate the water hammer effect, the pumped storage power counter-regulation problem is prominent, resulting in the minimum value of the power grid frequency f(t nadir1 ) (49.7669 Hz) and the steady-state value f st (49.9419 Hz) being the lowest, and the frequency change rate RoCoF (-0.0762 Hz / s) deteriorating significantly; while strategy two does not involve pumped storage in frequency modulation, so there is no deterioration of the water hammer effect on the frequency, but due to the lack of virtual inertia support of wind storage, the minimum value of the power grid frequency f(t nadir1 ) (49.8372 Hz), the frequency change rate RoCoF (-0.0668 Hz / s) and the steady-state value f st (49.9421 Hz) are lower, only slightly higher than those of strategy one. Quantitative analysis shows that the water hammer effect of pumped storage increases the frequency deviation of strategy one by 30.16%, and the RoCoF deteriorates by 13.38%, but strategy one includes pumped storage in the secondary frequency modulation resources of the system, which can effectively improve the overall frequency modulation effect of the system and avoid the limitation of single frequency modulation resource.

[0090] ​​​(2) In Strategy 3, the wind farm adopts the control strategy of this application to participate in frequency regulation (combining power reserve control and rotor kinetic energy control). Through the complementarity of the control strategy among the turbine groups, the frequency drop rate is slowed down and the water hammer effect is initially compensated, so that the minimum frequency is increased to 49.8763Hz (the minimum frequency deviation is reduced by 46.93% / 24.02% compared with Strategy 1 / 2), RoCoF is improved to -0.0543Hz / s (an increase of 29.60% / 18.73% compared with Strategy 1 / 2) and the steady-state value is significantly improved (49.9683Hz, the steady-state frequency deviation is reduced by 45.44% / 45.25% compared with Strategy 1 / 2); at the same time, the water hammer effect is compensated by pumped storage secondary frequency regulation, and the overall frequency regulation effect is significantly improved. However, since Strategy 3 does not consider the participation of energy storage in frequency regulation, there is a lack of active power output during the wind turbine speed recovery stage, the frequency drops twice, and the frequency regulation curve is not smooth enough. (3) In Strategy 4, both wind and energy storage adopt the control strategy of this application, realizing a dual compensation mechanism for the water hammer effect: on the one hand, the wind farm provides rapid power support through rotor kinetic energy control, and on the other hand, the energy storage system accurately fills the power gap. The synergistic effect of the two significantly reduces the impact on grid equipment. This strategy has improved key frequency regulation indicators in all aspects: the minimum frequency has increased to 49.8916Hz (the minimum frequency deviation has decreased by 53.50% / 33.42% / 12.37% compared with Strategy 1 / 2 / 3), RoCoF has improved to -0.0521Hz / s (an increase of 32.46% / 22.03% / 4.07% compared with Strategy 1 / 2 / 3), and the steady-state value has increased to 49.9708Hz (the deviation has decreased by 49.74% / 49.57% / 7.89% compared with Strategy 1 / 2 / 3). In addition, the active power compensation of energy storage during the wind turbine speed recovery stage has increased the minimum deviation of the second frequency drop by 22.38%, effectively suppressing the second frequency drop. In summary, compared with other strategies, Strategy 4 organically integrates the advantages of wind, storage, and energy storage for frequency regulation. It not only overcomes the limitations of a single frequency regulation resource, but also shortens the preparation time for pumped storage secondary frequency regulation by about 40% through the timing coordination between resources, which is conducive to the overall optimization of frequency regulation effect.

[0091] Among them, the wind turbine clusters in strategies three and four are based on Figure 8 The equivalent wind speed distribution diagrams for each turbine group are shown, based on an adapted control strategy to fully utilize their frequency regulation resources to support grid frequency regulation. The equivalent rotational speed of the first turbine group satisfies 0.99ω. C ≤ω eq ≤1.01ω C It is located in the constant speed region, but the equivalent electromagnetic power does not satisfy P. e_eq >0.9P e_max Therefore, overspeed unloading is adopted to reserve power margin, and virtual inertia support is provided through integrated inertia control; the equivalent speed of the second group of machines satisfies ωB <ω eq <0.99ω C , located in the MPPT zone, and the equivalent electromagnetic power satisfies P e_eq >0.55P e_max , uses comprehensive inertia control to participate in frequency modulation; the equivalent speed of the third machine group satisfies 0.99ω C ≤ω eq ≤1.01ω C , is located in the constant speed zone, and the equivalent electromagnetic power satisfies P e_eq >0.9P e_max , uses variable pitch and overspeed load shedding to release standby power frequency modulation to participate in frequency modulation; the equivalent speed of the fourth machine group does not satisfy 0.99ω C ≤ω eq ≤1.01ω C , is located in the constant power zone, uses variable pitch control to release standby power frequency modulation to participate in frequency modulation. The selection of the above strategy combines the operating characteristics of each machine group and the grid frequency modulation demand, realizing the maximum participation of the wind turbine in frequency modulation. The active power response curve corresponding to the four equivalent machine group strategies in the improved model of the application is shown in Figure 10 .

[0092] The output ΔP Bpump of the energy storage compensating water hammer effect, the output ΔP Bwind of the energy storage compensating wind turbine secondary drop, and the total output ΔP B of the energy storage are shown in Figure 11 . Combining the frequency modulation effect comparison of different strategies in Figure 9 , it can be found that the energy storage can make the frequency modulation curve smoother, and provide active support in time when the wind turbine frequency modulation resources are insufficient or the frequency drops twice.

[0093] Eighth embodiment To verify the superiority of the frequency modulation control strategy proposed in the application, a joint system three-region frequency control model is constructed based on the Matlab / Simulink simulation platform, as shown in Figure 12 .

[0094] Based on the wind storage collaborative frequency modulation and water hammer effect compensation control strategy under the full wind speed scene, region h contains a thermal power system, a wind turbine, and a pumped storage unit model; region i contains the thermal power system, wind turbine, pumped storage unit and energy storage battery model in Step 4; region j only contains a thermal power system. Considering the power structure characteristics of some areas in China, it is assumed that the output of the thermal power in the secondary frequency modulation in region h accounts for about 30%. In view of the uncontrollability of wind power generation in Step 4, random load disturbance is added to the AGC system of the three regions, so that the model is closer to the actual situation, and the region j model without pumped storage, the region h model with pumped storage, and the region i model with pumped storage and energy storage are simulated and compared respectively.

[0095] Figure 13 The global performance of the secondary frequency modulation in three cases is shown, Figure 14 The deviations of transient (a) and steady-state frequency (b) are compared respectively. The results show that, with the configuration of pumped storage and energy storage, the frequency deviation in both transient and steady state is significantly better than that without pumped storage or pumped storage alone.

[0096] In Figure 14 For example, in (b), without pumped storage, the maximum frequency deviation of the region in steady state is 0.0103 Hz; after adding pumped storage, the deviation is reduced to 0.0063 Hz, a decrease of 39.3%, and the frequency recovery speed is accelerated, effectively suppressing the frequency fluctuation between regions; when pumped storage and energy storage are configured at the same time, the deviation is further reduced to 0.0047 Hz, and compared with pumped storage alone, the maximum frequency deviation of the region is reduced by 25.4%.

[0097] As Figure 15 shown, the output adjustment range of pumped storage is about 4-5 times that of the thermal power system in the 270-300s time period, indicating that it has stronger adjustment capability.

[0098] The application of pumped storage to frequency modulation can increase the frequency modulation reserve capacity, enhance the system anti-interference ability, accelerate the frequency and tie-line fluctuation recovery speed, and provide strong support for the power grid; in the ARR mode, the continuous output of energy storage can effectively improve the steady-state frequency deviation, further reduce the frequency fluctuation, and significantly improve the system frequency modulation performance, Figure 16 corresponding to the energy storage response AGC output.

[0099] Based on the above research, the storage-coordinated control strategy proposed in the present application has significant advantages in improving the frequency stability of the system, can effectively suppress the transient frequency fluctuation of the power system, significantly reduce the steady-state frequency deviation, and comprehensively improve the secondary frequency modulation performance of the system.

[0100] As an implementation scheme, Figure 17 is a schematic diagram of the architecture of the hardware running environment of the computer system involved in the embodiment scheme of the present application.

[0101] As Figure 17As shown, the computer system can include a processor 1001, such as a CPU, a memory 1005, a user interface 1003, a network interface 1004, and a communication bus 1002. The communication bus 1002 is used to realize the connection communication between the components. The user interface 1003 can include a display screen (Display), an input unit such as a keyboard (Keyboard), and the optional user interface 1003 can also include a standard wired interface, a wireless interface. The network interface 1004 can optionally include a standard wired interface, a wireless interface (such as a WI-FI interface). The memory 1005 can be a high-speed RAM memory, or a stable memory (non-volatile memory) such as a disk memory. The memory 1005 can also be a storage device independent of the aforementioned processor 1001.

[0102] Those skilled in the art can understand that Figure 1 The computer system architecture shown in the embodiment does not constitute a limitation on the computer system, and can include more or fewer components than shown, or combine certain components, or different component arrangements.

[0103] As Figure 17 As shown, the memory 1005 as a storage medium can include an operating system, a network communication module, a user interface module, and a computer program. The operating system is a program that manages and controls the hardware and software resources of the computer system, and the running of the computer program and other software or programs.

[0104] In Figure 17 In the computer system shown, the user interface 1003 is mainly used to connect the terminal and communicate data with the terminal; the network interface 1004 is mainly used for the background server and communicates data with the background server; and the processor 1001 can be used to call the computer program stored in the memory 1005.

[0105] In the embodiment, the computer system includes a memory 1005, a processor 1001, and a computer program stored on the memory and executable on the processor, wherein: When the processor 1001 calls the computer program stored in the memory 1005, the following operations are performed: S10, when detecting that the water hammer effect occurs in the pumped storage system, the rotor kinetic energy strategy is used to control the frequency regulation of the fan system, and the energy storage system is controlled to compensate power when the output power of the fan system is reduced; S20, determining the same direction dead zone difference between the actual output of the thermal power system and the automatic generation control instruction, and controlling the pumped storage system and the energy storage system to cooperatively compensate the power meeting the same direction dead zone difference.

[0106] When the processor 1001 invokes the computer program stored in the memory 1005, the following operations are performed: S11, obtaining a frequency change rate and a frequency deviation of the fan system; S12, determining a target frequency modulation power increment of the fan system according to the frequency change rate and the frequency deviation, wherein a calculation expression of the target frequency modulation power is: In the formula, is a target frequency modulation power increment of the fan primary frequency modulation; Δf is a system frequency deviation; is a frequency change rate; is a virtual inertia coefficient, is a droop coefficient; S13, controlling the fan system to perform frequency modulation based on the target frequency modulation power increment.

[0107] When the processor 1001 invokes the computer program stored in the memory 1005, the following operations are performed: The virtual inertia coefficient and the droop coefficient are both adjusted according to the frequency change rate; Wherein the adjusted virtual inertia parameter satisfies the following expression:

[0108] In the formula, the time constant T is proportional to the output power under virtual inertia control and the frequency modulation exit time, and s is a Laplace operator; Wherein the adjusted droop parameter K 2,1 satisfies the following expression:

[0109] In the formula, t is the current simulation time, t re is the fan frequency modulation exit time, k c is a parameter of control change rate.

[0110] When the processor 1001 invokes the computer program stored in the memory 1005, the following operations are performed: S14, calculating a current water hammer output compensation power of the energy storage system required for compensation : In the formula, TB is a constant of energy storage converter; , is a fast compensation coefficient of energy storage self-adjusted according to the running state, which is used to accurately offset the pumping storage power reverse adjustment; represents a first-order inertia link energy storage converter dynamics; S15, calculating required compensation energy storage support power of the energy storage system : wherein, is an energy storage additional coefficient, is rated power of the fan system, is real-time power of the fan system; is rated power of the energy storage system; wherein: wherein; is a slope of the Logistic curve, is a center point of the Logistic curve, is a maximum value of the energy storage additional coefficient; S16, taking a sum of the current water hammer output compensation power and the energy storage support power as total power compensation power of the energy storage system :

[0111] S17, controlling the energy storage system to perform power compensation based on the total power compensation power .

[0112] When the processor 1001 invokes a computer program stored in the memory 1005, the following operations are performed: the energy storage fast compensation coefficient satisfies: wherein, represents an energy storage reference compensation coefficient, used to adjust water hammer effect compensation intensity; represents fan rotor angular velocity; if the frequency of the doubly-fed asynchronous wind power generator after exiting frequency regulation still does not satisfy the frequency requirement, a new energy storage droop fast compensation coefficient K B2,1 satisfies; the energy storage support power satisfies:

[0113] wherein:

[0114] .

[0115] When the processor 1001 invokes the computer program stored in the memory 1005, the following operations are performed: S21, determine the current stage of the thermal power system, the current stage including one of a response stage, a climbing stage and a stable stage; S22, determine the target compensation strategy of the pumped storage system and the energy storage system according to the current stage of the thermal power system; S23, control the pumped storage system and the energy storage system to compensate the power meeting the same-direction dead-zone difference according to the target compensation strategy.

[0116] When the processor 1001 invokes the computer program stored in the memory 1005, the following operations are performed: S221, when the thermal power system is in the response stage, control the pumped storage system and the energy storage system to compensate the first power meeting the same-direction dead-zone difference : In the formula, ΔP pump (t) is the power deviation of the pumped storage unit at time t; ΔP bcss (t) is the power deviation of the energy storage battery at time t; S222, when the thermal power system is in the climbing stage, determine the power distribution ratio of the pumped storage system and the energy storage system according to the available frequency modulation capacity of the pumped storage system and the energy storage system, control the pumped storage system and the energy storage system to compensate the second power meeting the same-direction dead-zone difference : In the formula, α、 are power distribution ratios, is the power deviation of the pumped storage system at time t, is the power deviation of the energy storage system at time t; wherein the calculation expression of the power distribution ratio is: In the formula, is the available frequency modulation capacity of the pumped storage system at time t; is the remaining frequency modulation capacity of the energy storage system; S223, when the thermal power system is in the stable stage, optimize the processing distribution of the pumped storage system and the energy storage system with the target of minimizing the steady-state frequency deviation.

[0117] When the processor 1001 invokes a computer program stored in the memory 1005, the following operations are performed: S2231, determining a steady-state frequency deviation in the pumped storage system and the energy storage system In the formula, Δf1(t) and Δf2(t) are steady-state frequency deviations of the dead zone and the linear response zone at time t, respectively; S2232, determining a smooth output of the energy storage system according to the state frequency deviation In the formula, K droop is an energy storage droop coefficient; S2233, calculating a support output of the pumped storage system according to the smooth output In the formula, K is a frequency deviation coefficient; is a generator droop coefficient; is a system load change; S2234, controlling the energy storage system to perform power compensation based on the smooth output , and controlling the pumped storage system to perform power compensation based on the support output .

[0118] In addition, a person of ordinary skill in the art can understand that all or part of the processes in the method of implementing the above embodiments can be completed by a computer program instructing related hardware. The computer program includes program instructions, and the computer program can be stored in a storage medium, which is a computer-readable storage medium. The program instructions are executed by at least one processor in a computer system to implement the process steps of the above-mentioned embodiments of the method.

[0119] Therefore, the application also provides a computer-readable storage medium storing a computer program, which is executed by a processor to implement each step of the frequency control optimization method based on a wind-pumped storage-energy storage combined system as described in the above embodiments.

[0120] The computer-readable storage medium can be a U disk, a mobile hard disk, a read-only memory (ROM), a magnetic disk or an optical disk, and various computer-readable storage media that can store program codes.

[0121] ​​​​​It should be noted that the storage medium provided by the embodiments of the present application is a storage medium used for implementing the method of the embodiments of the present application, and therefore, based on the method introduced in the embodiments of the present application, the specific structure and variations of the storage medium can be understood by those skilled in the art, and therefore, will not be described here. Any storage medium used by the method of the embodiments of the present application belongs to the scope of the present application.

[0122] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system or a computer program product. Therefore, the present application can adopt a completely hardware embodiment, a completely software embodiment or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program codes.

[0123] The present application is described with reference to flowcharts and / or block diagrams according to the method, device (system) and computer program product of the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams can be implemented by computer program instructions, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs the functions specified in one or more flows and / or blocks.

[0124] These computer program instructions can also be stored in a computer readable memory capable of guiding the computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer readable memory produce a product including instruction apparatus, which implements the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs the functions specified in one or more flows and / or blocks.

[0125] These computer program instructions can also be loaded into a computer or other programmable data processing device, so that a series of operation steps are performed on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide a process for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs the functions specified in one or more flows and / or blocks.

[0126] It should be noted that any reference signs placed between parentheses in the claims should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. This application can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

[0127] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0128] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A frequency regulation control optimization method based on a wind-storage-energy storage combined system, characterized in that, Applied to a hybrid power generation system including wind turbine systems, pumped storage systems, energy storage systems, and thermal power systems, the method includes the following steps: S10, when a water hammer effect is detected in the pumped storage system, the rotor kinetic energy strategy is used to control the wind turbine system to adjust the frequency, and when the output power of the wind turbine system decreases, the energy storage system is controlled to perform power compensation. S20, determine the dead zone difference between the actual output of the thermal power system and the automatic power generation control command, and control the pumped storage system and the energy storage system to coordinate and compensate for the power to meet the dead zone difference.

2. The method as described in claim 1, characterized in that, In step S10, the frequency regulation of the wind turbine system using a rotor kinetic energy strategy includes the following steps: S11, Obtain the frequency change rate and frequency deviation of the wind turbine system; S12, determine the target frequency regulation power increment of the wind turbine system based on the frequency change rate and the frequency deviation, wherein the calculation expression for the target frequency regulation power is: ； In the formula, Δf represents the target frequency regulation power increment for the primary frequency regulation of the wind turbine; Δf represents the system frequency deviation. The rate of change of frequency; For virtual inertia coefficients, This is the droop coefficient; S13, control the wind turbine system to perform frequency regulation based on the target frequency regulation power increment.

3. The method as described in claim 2, characterized in that, Both the virtual inertia coefficient and the droop coefficient are adjusted with the rate of change of frequency; Among them, the adjusted virtual inertial parameters Satisfy the following expression: ； In the formula, the time constant T is proportional to the output power and frequency modulation exit time under virtual inertial control, and s is the Laplace operator; Among them, the adjusted droop parameter K 2,1 Satisfy the following expression: ； In the formula, t is the current simulation time, t re k is the time for the wind turbine to exit frequency regulation. c Parameters used to control the rate of change.

4. The method as described in claim 1 or 2, characterized in that, In step S10, the step of controlling the energy storage system to perform power compensation includes: S14, Calculate the current water hammer output compensation power required by the energy storage system. : ； In the formula, TB is the constant of the energy storage converter; , This is a self-adjusting energy storage rapid compensation coefficient based on operating status, used to accurately offset the reverse adjustment of pumped storage power; This represents the dynamics of a first-order inertial energy storage converter. S15, Calculate the required compensation power of the energy storage system. : ； In the formula, For energy storage additional coefficient, The rated power of the fan system. This represents the real-time power of the wind turbine system. This refers to the rated power of the energy storage system. in: ； In the formula; Let be the slope of the Logistic curve. The center point of the Logistic curve, This represents the maximum value of the energy storage additional coefficient; S16, the current water hammer output compensation power With the energy storage support power The sum of these values ​​serves as the total power compensation power of the energy storage system. : ； S17, control the energy storage system based on the total power compensation power. Perform power compensation.

5. The method as described in claim 4, characterized in that, The energy storage rapid compensation coefficient satisfy: ； In the formula, This represents the energy storage baseline compensation coefficient, used to adjust the compensation intensity for water hammer effect; Indicates the angular velocity of the fan rotor; If the frequency of the doubly-fed asynchronous wind turbine after it is removed from frequency regulation still does not meet the frequency requirements, then a new energy storage droop compensation coefficient K is needed. B2,1 satisfy: ； The energy storage support power satisfy: ； in: ； 。 6. The method as described in claim 1, characterized in that, S20 specifically includes: S21, determine the current stage of the thermal power system, wherein the current stage includes one of the response stage, ramp-up stage, and stabilization stage; S22, Determine the target compensation strategy for the pumped storage system and the energy storage system based on the current stage of the thermal power system; S23, based on the same-direction dead zone difference, control the pumped storage system and the energy storage system to collaboratively compensate for the power that satisfies the same-direction dead zone difference according to the target compensation strategy.

7. The method as described in claim 6, characterized in that, The target compensation strategy includes: S221, when the thermal power system is in the response phase, control the pumped storage system and the energy storage system to coordinate compensation to meet the first power requirement of the same-direction dead zone difference. : ； In the formula, ΔP pump (t) represents the power deviation of the pumped storage unit at time t; ΔP bcss (t) represents the power deviation of the energy storage battery at time t; S222, when the thermal power system is in the ramp-up phase, based on the available frequency regulation capacity of the pumped storage system and the energy storage system, determine the respective power allocation ratios of the pumped storage system and the energy storage system, and control the pumped storage system and the energy storage system to compensate for the second power that satisfies the same-direction dead zone difference while meeting their respective power allocation ratios. : ； ； In the formula, α, All of these are power allocation ratios. Let t be the power deviation of the pumped storage system at time t. Let be the power deviation of the energy storage system at time t; The calculation expression for the power allocation ratio is as follows: ； In the formula, Let t be the available frequency regulation capacity of the pumped storage system at time t; This represents the remaining frequency regulation capacity of the energy storage system. S223, when the thermal power system is in a stable phase, optimize the processing allocation of the pumped storage system and the energy storage system with the goal of minimizing the steady-state frequency deviation.

8. The method as described in claim 7, characterized in that, In step S223, the step of optimizing the processing allocation of the pumped hydro storage system and the energy storage system with the goal of minimizing the steady-state frequency deviation includes: S2231, Determine the steady-state frequency deviation between the pumped hydro storage system and the energy storage system. : ； In the formula, Δf1(t) and Δf2(t) are the steady-state frequency deviations of the dead zone and the linear response zone at time t, respectively; S2232, according to the state frequency deviation Determine the smooth output of the energy storage system : ； In the formula, K droop This refers to the energy storage droop factor. S2233, according to the smooth output force Calculate the supporting output of the pumped storage system. : ； In the formula, Frequency deviation coefficient; Generator droop coefficient; This refers to the change in system load. S2234, Control the energy storage system based on the smooth output Perform power compensation and control the pumped storage system based on the support output. Perform power compensation.

9. A computer system, characterized in that, The computer system includes: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, it implements the steps of the frequency regulation control optimization method based on the wind-storage-energy storage combined system as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the frequency regulation control optimization method based on a wind-storage-energy storage combined system as described in any one of claims 1 to 8.

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