Frequency modulation method, system, device and medium for wind farm combined with energy storage

Abstract

The present invention discloses a frequency regulation method, system, equipment and medium involving wind farms and energy storage, and relates to the field of power system frequency regulation. The method comprises the following steps: obtaining power system data and energy storage system data for a current period; calculating a first minimum inertia of the power system for the current period based on the power system data for the current period; calculating a frequency regulation inertia of the energy storage system for the current period based on the unbalanced power of the power system for the current period and the energy storage system data for the current period; determining the larger of the frequency regulation inertia of the energy storage system for the current period and the first minimum inertia for the current period as the second minimum inertia of the power system for the current period; and inputting the second minimum inertia for the current period into an optimized frequency regulation model to predict a frequency regulation plan for the next period. The present invention can provide effective frequency regulation to meet the requirements of power system stability.

Description

Technical Field

[0001] The present invention relates to the field of power system frequency regulation, and in particular to a frequency regulation method, system, equipment and medium involving wind farm combined with energy storage. Background Art

[0002] Building a new power system dominated by renewable energy is a strong support for achieving the "dual carbon" goals and an effective means of addressing the dual pressures of primary energy depletion and environmental pollution. With the increasing maturity of wind power technology and the continuous increase in the capacity of wind turbines, large-scale centralized development of wind power has become the primary means of increasing the proportion of renewable energy in the power system, and a key guarantee for building a new power system and achieving the "dual carbon" goals.

[0003] The rotor speed of traditional thermal or hydropower synchronous generators is inherently coupled to system frequency. When a power disturbance occurs in the grid, resulting in a power shortage, the synchronous generators automatically release rotor kinetic energy to generate inertia (inertia is an inherent physical property of the power system that manifests itself as a resistance to frequency changes, and inertia is a measure of inertia). This supports the system's active power imbalance and maintains frequency stability. However, with the increasing penetration of wind power in the power system, traditional synchronous generators are being replaced by wind turbines and photovoltaic power generation connected to the grid through converters. These renewable energy generators connect to the grid through converters, which control the wind turbine's output power. This completely decouples rotor speed from grid frequency and makes them incapable of responding to system frequency fluctuations. The integration of renewable energy sources reduces the overall system's inertia. Furthermore, to maximize wind energy utilization, wind turbines typically operate along the MPPT curve to maximize transmission power. This means that in the event of a system power shortage, wind turbines are unable to provide power support, resulting in a lack of power reserve.

[0004] In severe cases, the above situation may even cause the power system to collapse and even cause large-scale power outages. Due to the high proportion of renewable energy such as wind power in the power grid, the lack of inertia support during system failures causes the frequency to drop rapidly and exceed the low-frequency tolerance limit of the wind turbines, resulting in large-scale wind turbine disconnection, causing the system frequency to drop further, and ultimately triggering the low-frequency load reduction device, causing large-scale power outages. Therefore, the participation of wind turbines in primary frequency regulation through additional frequency control is of great significance for improving the system frequency response characteristics, reducing the frequency regulation pressure of synchronous machines, and promoting the sustainable development of wind power generation. However, the participation of wind turbine rotor kinetic energy control in the system primary frequency regulation is not sustainable and temporary, especially with the annual decline in the proportion of synchronous machines in the power system, relying solely on wind turbines to participate in system frequency regulation can no longer meet the system frequency stability. Summary of the Invention

[0005] The purpose of the present invention is to provide a frequency regulation method, system, equipment and medium for wind farm combined with energy storage, which can provide effective frequency regulation to meet the stability of the power system.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A frequency regulation method involving a wind farm and energy storage, the method being used in a power system;

[0008] The power system includes an energy storage system associated with a wind farm; the response characteristics of the energy storage system affect the inertia of the power system; the energy storage system includes: a synchronous generator set, a wind turbine set, and an energy storage device; the response characteristics include the rotational kinetic energy of the synchronous generator set, the rotational kinetic energy of the wind turbine set, the frequency modulation power of the energy storage device, and the load frequency of the energy storage system; the inertia of the power system represents the obstruction of the power system to the load frequency of the energy storage system under power imbalance disturbance;

[0009] The method comprises:

[0010] Obtaining power system data and energy storage system data for the current period; the power system data includes: the unbalanced power of the power system, the load frequency deviation of the power system, the load power deviation of the power system, and the rated load power of the power system; the energy storage system data includes: the frequency modulation power of the synchronous generator set, the frequency modulation power of the wind turbine set, and the frequency modulation power of the energy storage device;

[0011] Calculating a first minimum inertia of the power system in the current period based on power system data for the current period; the first minimum inertia being the sum of the inertia of the power system at the time when the frequency change rate is maximum in the current period and the change in inertia of the power system in the current period; the frequency change rate being the first-order derivative of the load frequency deviation of the power system with respect to time;

[0012] Calculate the frequency regulation inertia of the energy storage system in the current period based on the unbalanced power of the power system in the current period and the energy storage system data in the current period;

[0013] Determining the larger of the frequency regulation inertia of the energy storage system in the current period and the first minimum inertia in the current period as the second minimum inertia of the power system in the current period;

[0014] The second minimum inertia of the current period is input into the optimized frequency regulation model to predict the frequency regulation plan for the next period; the frequency regulation plan for the next period is used to adjust the inertia of the power system in the current period to obtain the adjusted inertia of the power system in the current period; the adjusted inertia of the power system in the current period is used as the inertia of the power system in the next period.

[0015] Optionally, the optimized frequency modulation model includes: a first optimized frequency modulation model, a second optimized frequency modulation model and a third optimized frequency modulation model;

[0016] The first optimized frequency modulation model predicts a frequency modulation scheme for a first time period based on first historical data;

[0017] The first historical data includes sampling data of a first historical period; the first period is a period of time in the future of the first historical period, and the first historical period is continuous with the first period;

[0018] The second optimized frequency modulation model predicts a frequency modulation scheme for a second period based on the second historical data; the frequency modulation scheme for the second period is used to update the frequency modulation scheme for the first period to obtain an updated frequency modulation scheme for the first period;

[0019] The second historical data includes sampling data of a second historical period; the second period is a period within the first period, and the second period and the first period have the same start time; the second historical period is a period within the first historical period, and the second historical period has the same end time;

[0020] The third optimized frequency modulation model predicts a frequency modulation scheme for a third period based on the third historical data; the frequency modulation scheme for the third period is used to further update the updated frequency modulation scheme for the first period to obtain a final frequency modulation scheme for the first period;

[0021] The third historical data includes sampling data of a third historical period; the third period is the next moment after the end moment of the first historical period; the third historical period is a period of time within the second historical period and is the same as the end moment of the second historical period;

[0022] The frequency modulation scheme for the next time period is determined based on the final frequency modulation scheme for the first time period.

[0023] Optionally, the calculation formula of the first minimum inertia of the power system in the current period is:

[0024] H′ min =H min +ΔH G ;

[0025]

[0026]

[0027]

[0028] Among them, H′ minis the first minimum inertia of the power system in the current period; H min is the inertia of the power system when the frequency change rate is the largest in the current period; ΔH G is the inertia change of the power system in the current period; ΔP is the unbalanced power of the power system; Δf is the load frequency deviation; ΔP U is the load power deviation; P L0 is the rated load power of the power system; F max is the maximum frequency change rate value; U0 is the initial voltage of the power system before the unbalanced disturbance, U is the instantaneous voltage of the power system before the unbalanced disturbance, k z is the constant impedance load proportional coefficient; k i is the constant current load proportional coefficient, k p is the constant power load proportional coefficient; t is the time; t o It is the time when the frequency change rate is the largest in the current period.

[0029] Optionally, the calculation formula for the frequency modulation inertia of the energy storage system in the current period is:

[0030]

[0031] Among them, H min(Δf) is the frequency regulation inertia of the energy storage system in the current period; ΔPt1 is the frequency regulation power of the synchronous generator set; ΔP is the unbalanced power of the power system; ΔP W is the frequency regulation power of the wind turbine; ΔP ES is the frequency modulation power of the energy storage device; R W is the primary frequency modulation rate of the wind turbine rotor kinetic energy; R ES is the primary frequency modulation rate of the energy storage device; R S K is the primary frequency regulation rate of the thermal power unit; L is the load frequency modulation coefficient; Δf is the load frequency deviation.

[0032] Optionally, the calculation formula of the second minimum inertia of the power system in the current period is:

[0033] H1 min =max{H′ min ,H min(Δf)};

[0034] Among them, H1 min is the second minimum inertia of the power system in the current period; H min(Δf) is the frequency regulation inertia of the energy storage system in the current period; H′ min is the first minimum inertia of the power system in the current period; Δf is the load frequency deviation.

[0035] A frequency regulation system incorporating wind farms and energy storage, the system comprising:

[0036] A data acquisition module is configured to acquire power system data and energy storage system data for the current period; the power system data includes: the unbalanced power of the power system, the load frequency deviation of the power system, the load power deviation of the power system, and the rated load power of the power system; the energy storage system data includes: the frequency modulation power of the synchronous generator set, the frequency modulation power of the wind turbine set, and the frequency modulation power of the energy storage device;

[0037] a first calculation module, configured to calculate a first minimum inertia of the power system in the current period based on power system data of the current period; the first minimum inertia being the sum of the inertia of the power system when the frequency change rate is maximum in the current period and the change in inertia of the power system in the current period; the frequency change rate being the first-order derivative of the load frequency deviation of the power system taken with respect to time;

[0038] A second calculation module is used to calculate the frequency regulation inertia of the energy storage system in the current period based on the unbalanced power of the power system in the current period and the energy storage system data in the current period;

[0039] a third calculation module, configured to determine the larger of the frequency regulation inertia of the energy storage system in the current period and the first minimum inertia in the current period as the second minimum inertia of the power system in the current period;

[0040] The prediction module is used to input the second minimum inertia of the current period into the optimized frequency regulation model to predict the frequency regulation plan for the next period; the frequency regulation plan for the next period is used to adjust the inertia of the power system in the current period to obtain the adjusted inertia of the power system in the current period; the adjusted inertia of the power system in the current period is used as the inertia of the power system in the next period.

[0041] An electronic device includes a memory and a processor, wherein the memory is used to store a computer program, and the processor runs the computer program to enable the electronic device to execute any one of the above-mentioned frequency regulation methods involving wind farms and energy storage.

[0042] A computer-readable storage medium stores a computer program, wherein when the computer program is executed by a processor, the frequency regulation method involving a wind farm and energy storage as described above is implemented.

[0043] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0044] The present invention provides a frequency regulation method, system, device and medium for wind farm combined with energy storage, which calculates the first minimum inertia of the power system in the current period according to the power system data of the current period; calculates the frequency regulation inertia of the energy storage system in the current period according to the unbalanced power of the power system in the current period and the energy storage system data of the current period; determines the larger of the frequency regulation inertia of the energy storage system in the current period and the first minimum inertia in the current period as the second minimum inertia of the power system in the current period; inputs the second minimum inertia of the current period into the optimized frequency regulation model to predict the frequency regulation plan for the next period; the frequency regulation plan for the next period is used to adjust the inertia of the power system in the current period, and obtains the current The inertia of the power system after adjustment in the current period is used as the inertia of the power system in the next period. Since the present invention combines the unbalanced power of the power system and the frequency regulation power of the energy storage system to obtain the second minimum inertia of wind power and energy storage, the frequency stability of the power system is maintained according to the second minimum inertia, thereby maximizing the transmission power. Moreover, since the frequency regulation scheme at the next moment is predicted based on the second minimum inertia of the power system in the current period by using an optimized frequency regulation model to adjust the inertia of the power system, the frequency regulation scheme of the power system can be corrected, and the frequency response of the power system can be improved. Therefore, the present invention can provide effective frequency regulation to meet the stability of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 A flow chart of a frequency regulation method involving a wind farm and energy storage provided by an embodiment of the present invention;

[0047] Figure 2 This is a structural diagram of a frequency regulation system involving wind farms and energy storage provided by an embodiment of the present invention.

[0048] Explanation of symbols:

[0049] Data acquisition module-1, first calculation module-2, second calculation module-3, third calculation module-4, prediction module-5. DETAILED DESCRIPTION

[0050] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0051] The purpose of the present invention is to provide a frequency regulation method, system, equipment and medium for wind farm combined with energy storage, which can provide effective frequency regulation to meet the stability of the power system.

[0052] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] Example 1

[0054] like Figure 1 As shown, an embodiment of the present invention provides a frequency regulation method involving a wind farm and energy storage, which is used in a power system; the power system includes a wind farm and an energy storage system; the response characteristics of the energy storage system affect the inertia of the power system; the energy storage system includes: a synchronous generator set, a wind turbine set and an energy storage device; the response characteristics include the rotational kinetic energy of the synchronous generator set, the rotational kinetic energy of the wind turbine set, the frequency regulation power of the energy storage device and the load frequency of the energy storage system; the inertia of the power system represents the obstruction of the power system to the load frequency of the energy storage system under power imbalance disturbance.

[0055] The method comprises:

[0056] Step 100: Obtain power system data and energy storage system data for the current time period; the power system data includes: the unbalanced power of the power system, the load frequency deviation of the power system, the load power deviation of the power system, and the rated load power of the power system; the energy storage system data includes: the frequency modulation power of the synchronous generator set, the frequency modulation power of the wind turbine set, and the frequency modulation power of the energy storage device.

[0057] Step 200: Calculate the first minimum inertia of the power system in the current period based on the power system data of the current period; the first minimum inertia is the sum of the inertia of the power system when the frequency change rate is the largest in the current period and the inertia change of the power system in the current period; the frequency change rate is the first-order derivative of the load frequency deviation of the power system with respect to time.

[0058] Specifically, the calculation formula for the first minimum inertia of the power system in the current period is:

[0059] H′ min =H min +ΔH G ;

[0060]

[0061]

[0062]

[0063] Among them, H′ min is the first minimum inertia of the power system in the current period; H min is the inertia of the power system when the frequency change rate is the largest in the current period; ΔH G is the inertia change of the power system in the current period; ΔP is the unbalanced power of the power system; Δf is the load frequency deviation; ΔP U is the load power deviation; P L0 is the rated load power of the power system; F max is the maximum frequency change rate value; U0 is the initial voltage of the power system before the unbalanced disturbance, U is the instantaneous voltage of the power system before the unbalanced disturbance, k z is the constant impedance load proportional coefficient; k i is the constant current load proportional coefficient, k p is the constant power load proportional coefficient; t is the time; t o It is the time when the frequency change rate is the largest in the current period.

[0064] Step 300: Calculate the frequency regulation inertia of the energy storage system in the current period based on the unbalanced power of the power system in the current period and the energy storage system data in the current period.

[0065] Specifically, the calculation formula for the frequency modulation inertia of the energy storage system in the current period is:

[0066]

[0067] Among them, H min(Δf) is the frequency regulation inertia of the energy storage system in the current period; ΔPt1 is the frequency regulation power of the synchronous generator set; ΔP is the unbalanced power of the power system; ΔP W is the frequency regulation power of the wind turbine; ΔP ES is the frequency modulation power of the energy storage device; R W is the primary frequency modulation rate of the wind turbine rotor kinetic energy; R ES is the primary frequency modulation rate of the energy storage device; R S K is the primary frequency regulation rate of the thermal power unit; L is the load frequency modulation coefficient; Δf is the load frequency deviation.

[0068] Step 400: Determine the larger of the frequency regulation inertia of the energy storage system in the current period and the first minimum inertia in the current period as the second minimum inertia of the power system in the current period.

[0069] Specifically, the calculation formula of the second minimum inertia of the power system in the current period is:

[0070] H1 min =max{H′ min ,H min(Δf)};

[0071] Among them, H1 min is the second minimum inertia of the power system in the current period; H min(Δf) is the frequency regulation inertia of the energy storage system in the current period; H′ min is the first minimum inertia of the power system in the current period; Δf is the load frequency deviation.

[0072] Step 500: Input the second minimum inertia of the current period into the optimized frequency regulation model to predict the frequency regulation plan for the next period; the frequency regulation plan for the next period is used to adjust the inertia of the power system in the current period to obtain the adjusted inertia of the power system in the current period; the adjusted inertia of the power system in the current period is used as the inertia of the power system in the next period.

[0073] The optimized frequency modulation model includes: a first optimized frequency modulation model, a second optimized frequency modulation model and a third optimized frequency modulation model.

[0074] The first optimized frequency modulation model predicts a frequency modulation scheme for a first time period based on first historical data; the first historical data includes sampling data of the first historical time period; the first time period is a period of time in the future of the first historical time period, and the first historical time period is continuous with the first time period.

[0075] The second optimized frequency modulation model predicts the frequency modulation scheme for the second time period based on the second historical data; the frequency modulation scheme for the second time period is used to update the frequency modulation scheme for the first time period to obtain an updated frequency modulation scheme for the first time period; the second historical data includes sampling data for the second historical time period; the second time period is a period within the first time period, and the second time period has the same start time as the first time period; the second historical time period is a period within the first historical time period, and has the same end time as the first historical time period.

[0076] The third optimized frequency modulation model predicts the frequency modulation scheme of the third time period based on the third historical data; the frequency modulation scheme of the third time period is used to update the updated frequency modulation scheme of the first time period again to obtain the final frequency modulation scheme of the first time period; the third historical data includes sampling data of the third historical time period; the third time period is the next moment after the end moment of the first historical time period; the third historical time period is a period of time within the second historical time period, and is the same as the end moment of the second historical time period.

[0077] The frequency modulation scheme for the next time period is determined based on the final frequency modulation scheme for the first time period.

[0078] In practical applications, the frequency modulation method for wind farms combined with energy storage provided by the present invention may also be implemented in the following specific steps:

[0079] Step 1: Calculate the minimum inertia requirement to offset the system power imbalance disturbance without considering frequency modulation resources.

[0080] The system frequency dynamic equation is as follows:

[0081]

[0082] Where Hs is the system inertia; ΔP is the unbalanced power of the power system; ΔP G is the synchronous machine frequency modulation power, ΔP W is the frequency regulation power of the wind turbine; ΔP ES is the frequency modulation power of the energy storage device, ΔP L is the load frequency modulation power, and Δf is the load frequency deviation.

[0083] At the moment of system power imbalance disturbance, the system inertia is minimum, resulting in the maximum frequency change rate. The frequency change rate at this time is used as a constraint to evaluate the system minimum inertia requirement. Since the system frequency has no deviation at the beginning of the disturbance, the synchronous generator and load cannot respond to the system frequency regulation effect. Their frequency change is only related to the system inertia and the disturbance power, as shown below:

[0084]

[0085] Where Hs is the system inertia; ΔP is the unbalanced power of the power system; and Δf is the load frequency deviation.

[0086] It can be obtained that the minimum inertia of the system under the frequency change rate constraint is:

[0087]

[0088] Where ΔP is the unbalanced power of the power system; Δf is the load frequency deviation; t is any moment; t oFor a certain moment; F max is the maximum frequency change rate value.

[0089] At the moment of power disturbance, the static voltage power of the inductive load also provides a certain inertia support to the system, as follows:

[0090]

[0091] H min is the inertia of the power system when the frequency change rate is the largest in the current period, that is, H min is the minimum inertia under the frequency change rate constraint; ΔP is the unbalanced power of the power system; ΔP U is the load power deviation; F max is the maximum frequency change rate value.

[0092]

[0093] U0 is the initial voltage of the power system before the unbalanced disturbance, U is the instantaneous voltage of the power system before the unbalanced disturbance, k z is the constant impedance load proportional coefficient; k i is the constant current load proportional coefficient, k p is the constant power load proportional coefficient; ΔP U is the load power deviation; P L0 is the rated load power of the power system.

[0094] The above model does not consider the source of the power shortfall ΔP, such as the disturbance power ΔP caused by a DC blocking fault, which does not affect the inertia level of the entire system. If an AC line disconnection or synchronous generator trip occurs, the system inertia will be reduced, further deteriorating the system frequency.

[0095] At this time, the first minimum inertia requirement value is:

[0096] H′ min =H min +ΔH G ;

[0097] H′ min is the first minimum inertia of the power system in the current period; H min is the inertia of the power system when the frequency change rate is the largest in the current period; ΔH G is the inertia change of the power system in the current period; ΔH G It indicates the change in inertia caused by the exit of synchronous generator sets or AC line short circuit, which reduces the inertia of the system.

[0098] Step 2: Under the premise of fully considering the frequency regulation resources, calculate the inertia that the frequency regulation resources can provide. Combined with the above-mentioned first minimum inertia requirement, further calculate the second minimum inertia requirement that requires the participation of wind farms and energy storage.

[0099] Under power shortage, the response speed of each frequency regulation resource in the power system is different, and the frequency regulation scale of the participating systems is also different. The frequency regulation resources involved in the present invention include the frequency response characteristics of the load, the virtual inertia control of the energy storage device, the virtual inertia control of the wind turbine, and the frequency regulation characteristics of the synchronous unit.

[0100] The natural properties of load frequency response first respond to system frequency changes and narrow the power difference. Secondly, due to the fast response speed of energy storage, it provides virtual inertia in a timely manner to further reduce the power imbalance. Then, the wind turbine provides inertia support through rotor kinetic energy, suppressing further expansion of frequency deviation. Finally, the synchronous generator set is started with a frequency regulation to supplement the power imbalance of the system.

[0101] The present invention calculates the second minimum inertia value of the system with the maximum frequency offset in four stages. The times corresponding to the four stages are t1, t2, t3, and t4, the corresponding time periods are Δt1, Δt2, Δt3, and Δt4, and the corresponding frequency deviations are Δf1, Δf2, Δf3, and Δf4.

[0102] From the time 0 when the fault occurs to the time t4 when the system frequency deviation reaches the extreme value, the piecewise linearization method is used to perform the integral solution, as follows:

[0103]

[0104] Where Hs is the system inertia; ΔP is the unbalanced power of the power system; ΔP G is the synchronous machine frequency modulation power, ΔP W is the frequency regulation power of the wind turbine; ΔP ES is the frequency modulation power of the energy storage device; ΔP L is the load frequency modulation power.

[0105] During the 0-t1 period, all frequency control devices are not activated, and the system active power imbalance ΔP remains unchanged, that is:

[0106]

[0107] Where ΔP is the unbalanced power of the power system; ΔP G is the synchronous machine frequency modulation power; ΔP W is the frequency regulation power of the wind turbine; ΔP ES Frequency modulation power for energy storage devices.

[0108] During the t1-t2 phase, the energy storage device starts frequency modulation.

[0109]

[0110] Where ΔP is the unbalanced power of the power system; ΔP G is the synchronous machine frequency modulation power; ΔP W is the frequency regulation power of the wind turbine; ΔP ES is the frequency modulation power of the energy storage device; R ES is the primary frequency modulation rate of the energy storage device, specifically:

[0111]

[0112] During the t2-t3 phase, the wind turbine rotor kinetic energy auxiliary frequency control starts.

[0113]

[0114] Where ΔP is the unbalanced power of the power system; ΔP G is the synchronous machine frequency modulation power, ΔP W is the frequency regulation power of the wind turbine; ΔP ES is the frequency modulation power of the energy storage device; R W is the primary frequency modulation rate of the wind turbine rotor kinetic energy, specifically:

[0115]

[0116] Among them, P W Output power for wind turbines.

[0117] During the t3-t4 phase, the thermal power unit is started with a frequency modulation.

[0118]

[0119] Where ΔP is the unbalanced power of the power system; ΔP G is the synchronous machine frequency modulation power; ΔP W is the frequency regulation power of the wind turbine; ΔP ES is the frequency modulation power of the energy storage device; R S is the primary frequency regulation rate of the thermal power unit, specifically:

[0120]

[0121] Where ΔP is the unbalanced power of the power system; ΔP W is the frequency regulation power of the wind turbine.

[0122] Since the power absorbed by the wind turbine recovery control is taken into account during the t3-t4 period, the frequency regulation power provided by the generator is actually:

[0123]

[0124] Where ΔP is the unbalanced power of the power system; ΔP G is the synchronous machine frequency modulation power; ΔP W is the frequency regulation power of the wind turbine; ΔP ES is the frequency modulation power of the energy storage device; R S It is the primary frequency regulation rate of thermal power unit.

[0125] From this, the minimum inertia required by the system is:

[0126]

[0127] Among them, H min(Δf) is the frequency regulation inertia of the energy storage system in the current period; ΔPt1 is the frequency regulation power of the synchronous generator set; ΔP is the unbalanced power of the power system; ΔP W is the frequency regulation power of the wind turbine; ΔP ES is the frequency modulation power of the energy storage device; R W is the primary frequency modulation rate of the wind turbine rotor kinetic energy; R ES is the primary frequency modulation rate of the energy storage device; R S K is the primary frequency regulation rate of the thermal power unit; L is the load frequency modulation coefficient; Δf is the load frequency deviation; at this time, the value of Δf is the value of Δf4, which is equal to 1Hz.

[0128] According to the power system low-frequency load shedding setting method and setting scheme, the frequency setting value of the first round of load shedding in low-frequency load shedding is 49Hz. Therefore, Δf4 in this paper is 1Hz.

[0129] Therefore, the minimum inertia requirement of the power system, that is, the second minimum inertia of the power system is:

[0130] H min =max{H′ min ,H min(Δf)}

[0131] Among them, H1 min is the second minimum inertia of the power system in the current period; H min(Δf) is the frequency regulation inertia of the energy storage system in the current period; H′ min is the first minimum inertia of the power system in the current period; Δf is the load frequency deviation.

[0132] Step 3: Based on the wind farm output forecast data and load forecast data for the 24 hours before the day, evaluate the second minimum inertia demand of the system in the 24 hours before the day, provide the second minimum inertia demand values for 24 time periods, and formulate the day-ahead frequency regulation strategy.

[0133] By using the wind farm output curve and load power consumption curve obtained 24 hours before the day, the output curve of the traditional synchronous unit 24 hours before the day can be obtained through the power system dispatching system. Combined with the frequency response characteristics of the wind power system, synchronous generator system and load, the system power disturbance ΔP is used, and the frequency change rate and maximum frequency offset are used to obtain the system minimum inertia demand value with a resolution of 1 hour 24 hours before the day.

[0134] Taking the minimum inertia requirement value as a constraint, the primary frequency regulation strategy of wind farm combined with energy storage is optimized. The minimum inertia constraint is:

[0135] H s(t) ≥H min(t) , t∈[0, 24]

[0136] Where H s(t) represents the system inertia during period t, H min(t) is the minimum inertia requirement of the system during period t.

[0137] The objective function of the wind farm combined with energy storage participating in the system primary frequency regulation strategy in the past 24 hours is:

[0138]

[0139] Where, f i (P Gi (t) represents the operating cost of the synchronous unit, N G Indicates the number of synchronous units, s i (t) represents the state of the synchronous unit, where s i (t)=1, indicating the synchronous unit is in operation state, s i (t)=0 means the synchronous unit is out of operation, S i (t) represents the start-up and shutdown cost of the synchronous unit, ΔH ES Indicates the virtual inertia added by the energy storage device, c ES Indicates the unit cost of virtual inertia adjustment.

[0140] The constraint equation is:

[0141] The power and active power balance constraints of the power system are:

[0142]

[0143] Where N W Indicates the number of wind farms; N PV Indicates the number of photovoltaic power stations; N ES represents the number of energy storage power stations; P Gi (t) represents the output power of the i-th synchronous generator; P Wi(t) represents the output power of the i-th wind farm; P PVi (t) represents the output power of the i-th photovoltaic power station; P ESdi (t) represents the discharge power of the energy storage device; P ESci (t) represents the charging power of the energy storage device.

[0144] Output limit constraints for thermal power units:

[0145]

[0146] Wind turbine output limit constraints:

[0147]

[0148] Photovoltaic power generation output limit constraints:

[0149]

[0150] Power system node voltage limit constraints:

[0151] U i,min ≤U i,t ≤U i,max ;

[0152] Power system transmission line transmission power constraints:

[0153] |P ij,t |≤P ij,max ;

[0154] Energy storage device output limit constraints:

[0155] P ESd,min ≤P ESdi,t ≤P ESd,max ;

[0156] In a scheduling cycle, the initial and final power of the storage device are constrained to be the same as follows:

[0157] E ESd,0 =E ESd,24

[0158] Thermal power unit ramp constraints:

[0159] |E Gi,t+1 -E Gi,t |≤ΔP Gi,max ·Δt

[0160] Step 4: Based on the 4-hour wind farm output forecast data and load forecast, combined with the second minimum inertia demand values of the 24 time periods in the previous day, the 4-hour system second minimum inertia demand is evaluated. The second minimum inertia demand values of 16 time periods with a 15-minute resolution are rolled out to formulate the intraday frequency regulation strategy.

[0161] The objective function of the 4-hour wind farm combined with energy storage system primary frequency regulation strategy is:

[0162]

[0163] Where, f i (P Gi (t) represents the operating cost of the synchronous unit, NG Indicates the number of synchronous units, s i (t) represents the state of the synchronous unit, where s i (t)=1, indicating the synchronous unit is in operation state, s i (t)=0 means the synchronous unit is out of operation, S i (t) represents the start-up and shutdown cost of the synchronous unit, ΔH ES Indicates the virtual inertia added by the energy storage device, c ES Indicates the unit cost of virtual inertia adjustment.

[0164] The constraint equation is:

[0165]

[0166] Where N W Indicates the number of wind farms, N PV Indicates the number of photovoltaic power stations, N ES Indicates the number of energy storage power stations.

[0167] H s(t) ≥H min(t) , t∈[0,4], the constraint equations have changed, including the output power limits of thermal power units, wind farms, and photovoltaic power stations.

[0168]

[0169]

[0170]

[0171] U i,min ≤U i,t ≤U i,max

[0172] |P ij,t |≤P ij,max

[0173] P b,min ≤P bi,t ≤P b,max

[0174] P b,min ≤P bi,t≤P b,max

[0175] |E Gi,t+1 -E Gi,t |≤ΔP Gi,max ·Δt

[0176] Step 5: Based on the measured data and the second minimum inertia demand value of the system during the day, the primary frequency regulation strategy of the power system is optimized, and a solution for wind farms and energy storage to participate in the primary frequency regulation of the system is proposed.

[0177] The objective function of real-time optimization of the primary frequency regulation strategy of wind farm combined with energy storage is:

[0178]

[0179] Where N G Indicates the number of synchronous units; ΔH ES Indicates the virtual inertia added by the energy storage device; P ES is the power of the energy storage device.

[0180] The constraint equation is:

[0181]

[0182] Where N G Indicates the number of synchronous units; N W Indicates the number of wind farms; N PV Indicates the number of photovoltaic power stations; N ES Indicates the number of energy storage power stations.

[0183] The constraints are:

[0184] H s(t) ≥H min(t) ;

[0185] P Gi,min ≤P Gi,t ≤P Gi,max ;

[0186] 0≤P wi,t ≤P w ;

[0187] 0≤P pvi,t ≤P pv ;

[0188] U i,min ≤U i,t ≤U i,max ;

[0189] |P ij,t |≤P ij,max ;

[0190] Pb,min ≤P bi,t ≤P b,max ;

[0191] P b,min ≤P bi,t ≤P b,max ;

[0192] |E Gi,t+1 -E Gi,t |≤ΔP Gi,max Δt;

[0193] By obtaining a real-time frequency regulation strategy, the frequency response characteristics of the wind farm and energy storage device are adjusted in real time to ensure the frequency stability of the system.

[0194] Example 2

[0195] like Figure 2 As shown, an embodiment of the present invention provides a frequency regulation system in which a wind farm is combined with energy storage. The system includes: a data acquisition module 1, a first calculation module 2, a second calculation module 3, a third calculation module 4 and a prediction module 5.

[0196] Data acquisition module 1 is used to obtain the power system data and energy storage system data of the current time period; the power system data includes: the unbalanced power of the power system, the load frequency deviation of the power system, the load power deviation of the power system, and the rated load power of the power system; the energy storage system data includes: the frequency regulation power of the synchronous generator set, the frequency regulation power of the wind turbine set, and the frequency regulation power of the energy storage device.

[0197] The first calculation module 2 is used to calculate the first minimum inertia of the power system in the current period based on the power system data of the current period; the first minimum inertia is the sum of the inertia of the power system when the frequency change rate is the largest in the current period and the inertia change of the power system in the current period; the frequency change rate is the first-order derivative of the load frequency deviation of the power system with respect to time.

[0198] The second calculation module 3 is used to calculate the frequency regulation inertia of the energy storage system in the current period based on the unbalanced power of the power system in the current period and the energy storage system data in the current period.

[0199] The third calculation module 4 is configured to determine the larger of the frequency regulation inertia of the energy storage system in the current period and the first minimum inertia in the current period as the second minimum inertia of the power system in the current period.

[0200] Prediction module 5 is used to input the second minimum inertia of the current period into the optimized frequency regulation model to predict the frequency regulation plan for the next period; the frequency regulation plan for the next period is used to adjust the inertia of the power system in the current period to obtain the adjusted inertia of the power system in the current period; the adjusted inertia of the power system in the current period is used as the inertia of the power system in the next period.

[0201] Example 3

[0202] An embodiment of the present invention provides an electronic device, including a memory and a processor, wherein the memory is used to store a computer program, and the processor runs the computer program to enable the electronic device to execute the frequency modulation method involving wind farm combined with energy storage as described in any one of Embodiment 1.

[0203] As an optional implementation, an embodiment of the present invention further provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the frequency regulation method involving wind farms and energy storage as described in any one of Example 1.

[0204] The present invention comprehensively considers the frequency regulation resources of the power system, including the rotational kinetic energy of traditional synchronous generator sets, wind turbine sets, and the frequency response characteristics of the load itself, and obtains the output of traditional synchronous generator sets through the 24-hour wind power forecast of the wind farm and the power system load forecast data. According to the frequency response characteristics of both the source and the load, the minimum inertia requirement of the power system is evaluated. With the minimum inertia requirement of the power system, the power balance of the power system, the climbing of the synchronous generator sets, and the equipment operating limits as constraints, and with the goal of minimizing the sum of the operating costs of the traditional synchronous generator sets of the power system and the cost of increasing the virtual inertia, an optimal frequency regulation control strategy for the power system is constructed, and the optimal configuration scheme for the wind farm combined with energy storage to participate in the primary frequency regulation of the system is further obtained, that is, a 24-hour operation plan for the energy storage power station is given.

[0205] Taking into account the errors in the wind power forecast of the wind farm and the load forecast of the power system in the previous 24 hours, in order to further improve the effectiveness of the power system frequency regulation strategy, a 4-hour wind farm wind power and power system load forecast is proposed. Through the 4-hour forecast, the error between the forecast result and the actual operation is further reduced. According to the 4-hour forecast results, the output arrangement of the traditional generator set is corrected. By evaluating the minimum inertia requirement of the system, the optimal configuration scheme of the wind farm combined with energy storage to participate in the primary frequency regulation of the system is optimized, and the 4-hour operation plan of the energy storage power station is obtained. Through the measured data and compared with the 4-hour forecast results, the optimal configuration scheme of the wind farm combined with energy storage to participate in the primary frequency regulation of the system is quickly corrected, and the real-time operation plan of the energy storage power station is given to ensure that the power system has sufficient inertia level in real time and improve the frequency response capability of the power system under the high proportion of new energy access.

[0206] The advantages of the present invention are as follows:

[0207] 1. It can quickly correct the optimal configuration plan for wind farms and energy storage to participate in the system's primary frequency regulation, provide a real-time operation plan for the energy storage power station, ensure that the power system has sufficient inertia in real time, and improve the frequency response capability of the power system under the condition of a high proportion of renewable energy access.

[0208] 2. By optimizing frequency control, the economy of power system operation is improved while ensuring the frequency stability of the power system. At the same time, the method of the present invention is simple and practical, providing technical support for the construction of a high-proportion new energy power system.

[0209] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0210] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A frequency modulation method involving wind farms and energy storage, characterized in that: The method is used in an electric power system; The power system includes an energy storage system associated with a wind farm; the response characteristics of the energy storage system affect the inertia of the power system; the energy storage system includes: a synchronous generator set, a wind turbine set, and an energy storage device; the response characteristics include the rotational kinetic energy of the synchronous generator set, the rotational kinetic energy of the wind turbine set, the frequency modulation power of the energy storage device, and the load frequency of the energy storage system; the inertia of the power system represents the obstruction of the power system to the load frequency of the energy storage system under power imbalance disturbance; The method comprises: Obtaining power system data and energy storage system data for the current period; the power system data includes: the unbalanced power of the power system, the load frequency deviation of the power system, the load power deviation of the power system, and the rated load power of the power system; the energy storage system data includes: the frequency modulation power of the synchronous generator set, the frequency modulation power of the wind turbine set, and the frequency modulation power of the energy storage device; Calculating a first minimum inertia of the power system in the current period based on power system data for the current period; the first minimum inertia being the sum of the inertia of the power system at the time when the frequency change rate is maximum in the current period and the change in inertia of the power system in the current period; the frequency change rate being the first-order derivative of the load frequency deviation of the power system with respect to time; Calculate the frequency regulation inertia of the energy storage system in the current period based on the unbalanced power of the power system in the current period and the energy storage system data in the current period; Determining the larger of the frequency regulation inertia of the energy storage system in the current period and the first minimum inertia in the current period as the second minimum inertia of the power system in the current period; Inputting the second minimum inertia of the current period into the optimized frequency regulation model to predict a frequency regulation plan for the next period; the frequency regulation plan for the next period is used to adjust the inertia of the power system in the current period to obtain the adjusted inertia of the power system in the current period; the adjusted inertia of the power system in the current period is used as the inertia of the power system in the next period; The calculation formula for the frequency modulation inertia of the energy storage system in the current period is: Among them, H min(Δf) is the frequency regulation inertia of the energy storage system in the current period; ΔPt1 is the frequency regulation power of the synchronous generator set; ΔP is the unbalanced power of the power system; ΔP W is the frequency regulation power of the wind turbine; ΔP ES is the frequency modulation power of the energy storage device; R W is the primary frequency modulation rate of the wind turbine rotor kinetic energy; R ES is the primary frequency modulation rate of the energy storage device; R S K is the primary frequency regulation rate of the thermal power unit; L is the load frequency modulation coefficient; Δf is the load frequency deviation.

2. The frequency modulation method of wind farm combined with energy storage according to claim 1, characterized in that: The optimized frequency modulation model includes: a first optimized frequency modulation model, a second optimized frequency modulation model and a third optimized frequency modulation model; The first optimized frequency modulation model predicts a frequency modulation scheme for a first time period based on first historical data; The first historical data includes sampled data of a first historical period; the first period is a period of time in the future of the first historical period, and the first historical period is continuous with the first period; The second optimized frequency modulation model predicts a frequency modulation scheme for a second period based on the second historical data; the frequency modulation scheme for the second period is used to update the frequency modulation scheme for the first period to obtain an updated frequency modulation scheme for the first period; The second historical data includes sampling data of a second historical period; the second period is a period within the first period, and the second period and the first period have the same start time; the second historical period is a period within the first historical period, and the second historical period has the same end time; The third optimized frequency modulation model predicts a frequency modulation scheme for a third period based on the third historical data; the frequency modulation scheme for the third period is used to further update the updated frequency modulation scheme for the first period to obtain a final frequency modulation scheme for the first period; The third historical data includes sampling data of a third historical period; the third period is the next moment after the end moment of the first historical period; the third historical period is a period of time within the second historical period and is the same as the end moment of the second historical period; The frequency modulation scheme for the next time period is determined based on the final frequency modulation scheme for the first time period.

3. The frequency modulation method of wind farm combined with energy storage according to claim 1, characterized in that: The calculation formula of the first minimum inertia of the power system in the current period is: H′ min =H min +ΔH G ; Among them, H′ min is the first minimum inertia of the power system in the current period; H min is the inertia of the power system when the frequency change rate is the largest in the current period; ΔH G is the inertia change of the power system in the current period; ΔP is the unbalanced power of the power system; Δf is the load frequency deviation; ΔP U is the load power deviation; P L0 is the rated load power of the power system; F max is the maximum frequency change rate value; U0 is the initial voltage of the power system before the unbalanced disturbance, U is the instantaneous voltage of the power system before the unbalanced disturbance, k z is the constant impedance load proportional coefficient; k i is the constant current load proportional coefficient, k p is the constant power load proportional coefficient; t is the time; t o It is the time when the frequency change rate is the largest in the current period.

4. The frequency modulation method of wind farm combined with energy storage according to claim 1, characterized in that: The calculation formula of the second minimum inertia of the power system in the current period is: H1 min =max{H′ min ,H min(Δf) }; Among them, H1 min is the second minimum inertia of the power system in the current period; H min(Δf) is the frequency regulation inertia of the energy storage system in the current period; H′ min is the first minimum inertia of the power system in the current period; Δf is the load frequency deviation.

5. A frequency regulation system in which a wind farm is combined with energy storage, characterized in that: The system comprises: A data acquisition module is configured to acquire power system data and energy storage system data for the current period; the power system data includes: the unbalanced power of the power system, the load frequency deviation of the power system, the load power deviation of the power system, and the rated load power of the power system; the energy storage system data includes: the frequency modulation power of the synchronous generator set, the frequency modulation power of the wind turbine set, and the frequency modulation power of the energy storage device; a first calculation module, configured to calculate a first minimum inertia of the power system in the current period based on power system data of the current period; the first minimum inertia being the sum of the inertia of the power system when the frequency change rate is maximum in the current period and the change in inertia of the power system in the current period; the frequency change rate being the first-order derivative of the load frequency deviation of the power system taken with respect to time; A second calculation module is used to calculate the frequency regulation inertia of the energy storage system in the current period based on the unbalanced power of the power system in the current period and the energy storage system data in the current period; a third calculation module, configured to determine the larger of the frequency regulation inertia of the energy storage system in the current period and the first minimum inertia in the current period as the second minimum inertia of the power system in the current period; a prediction module, configured to input the second minimum inertia of the current period into the optimized frequency regulation model to predict a frequency regulation scheme for the next period; the frequency regulation scheme for the next period is used to adjust the inertia of the power system in the current period to obtain the adjusted inertia of the power system in the current period; the adjusted inertia of the power system in the current period is used as the inertia of the power system in the next period; The calculation formula for the frequency modulation inertia of the energy storage system in the current period is: Among them, H min(Δf) is the frequency regulation inertia of the energy storage system in the current period; ΔPt1 is the frequency regulation power of the synchronous generator set; ΔP is the unbalanced power of the power system; ΔP W is the frequency regulation power of the wind turbine; ΔP ES is the frequency modulation power of the energy storage device; R W is the primary frequency modulation rate of the wind turbine rotor kinetic energy; R ES is the primary frequency modulation rate of the energy storage device; R S K is the primary frequency regulation rate of the thermal power unit; L is the load frequency modulation coefficient; Δf is the load frequency deviation.

6. An electronic device, characterized in that: The electronic device comprises a memory and a processor, wherein the memory is used to store a computer program, and the processor runs the computer program to enable the electronic device to execute the frequency regulation method involving wind farm combined with energy storage as claimed in any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that It stores a computer program, which, when executed by a processor, implements the frequency regulation method involving wind farms and energy storage as claimed in any one of claims 1 to 4.

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