Wind power plant reactive power coordination method and device and storage medium

Abstract

The invention provides a wind power plant reactive power coordination method and device and a storage medium, and relates to the technical field of power systems and automation thereof, and the method comprises the steps: firstly monitoring the reactive power output and maximum reactive power output capability of each fan in real time, and synchronously obtaining the current voltage drop amount and the actual reactive power output power of a static var compensator (SVC); the reactive power margin of each fan is calculated, the total reactive power compensation requirement of the system is determined according to the voltage drop amount and the equivalent reactance of the power grid, and an initial compensation task is undertaken by the SVC; then distributing the residual compensation amount to each fan according to the fan reactive margin proportion, and generating an adjustment instruction after the current output is superposed and the current output is limited not to exceed the maximum capacity; if a certain fan still overruns after being adjusted, the overrun part is redistributed to other fans with margins until all the fans run within the safe range; finally, SVC output and power grid state changes are tracked in real time, compensation distribution is dynamically optimized, and balance of reactive power coordination is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems and automation thereof, and in particular to a wind farm reactive power coordination method, device and storage medium. Background Art

[0002] Wind power systems generally adopt a detection-and-disconnection strategy for faulty wind turbines, which can cause regional voltage collapse. Wind turbines with minor faults still have some power generation capacity, and most faults are temporary or non-structural. When blade cracks, generator winding short circuits, etc. occur, the wind turbines will be forced to disconnect from the grid. Therefore, for wind turbines with non-serious faults in wind farms, a strategy of derating operation with faults is required. At this time, when the reactive power supply and demand in the power grid are unbalanced, the voltage will deviate from the rated value, which may cause voltage collapse or equipment damage in severe cases. Especially when a power grid fault occurs or the load suddenly changes, the wind farm needs to respond quickly to the voltage drop and inject reactive power to maintain voltage stability.

[0003] Traditional reactive power compensation schemes mainly rely on static VAR compensation devices (SVCs), which have a fast response speed (millisecond level), but have the following limitations: the rated capacity of SVCs is fixed, and they may not be able to meet all reactive power demands during severe voltage drops; long-term full-load operation will accelerate the loss of core components such as SVC thyristors and shorten their service life; high-capacity SVC equipment, such as high-capacity STATCOM static synchronous compensators, is expensive and still has certain limitations on short-term large-capacity reactive power support, and does not fully utilize the reactive power regulation potential of the wind turbine itself. When the grid demand changes or the SVC (static VAR compensation device) cannot meet the demand due to capacity limitations, the traditional control strategy cannot adjust the wind turbine compensation task in real time, resulting in Voltage recovery delay or oscillation affects the stability of the power grid; modern doubly fed induction wind turbines (DFIGs) and full power converter wind turbines (PMSGs) both have certain reactive power regulation capabilities and can provide partial reactive power compensation by adjusting the power factor (PF) or reactive power instructions. However, the reactive power capacity of wind turbines is limited, and active power output is usually prioritized. Therefore, under extreme working conditions, they cannot fully meet the reactive power requirements of the power grid. Therefore, a method for combined reactive power regulation through SVC and wind turbines is now needed to effectively improve the reactive power support capacity of wind farms, reduce voltage fluctuations, allow faulty wind turbines to continue operating with limited reactive power output, avoid complete power outages affecting power grid stability, and improve the reliability and safety of wind power grid connection.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0005] The object of the present invention is to provide a method and device for reactive power coordination in a wind farm, so as to solve the problems raised in the above background technology.

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

[0007] The wind farm reactive power coordination method includes the following specific steps:

[0008] Step 1: Real-time data collection of bus voltage and wind farm grid connection point voltage is used to calculate voltage drop. When the voltage drop exceeds the set voltage drop threshold, the active power output of the non-faulty wind turbines is restricted.

[0009] Step 2: Calculate the reactive power margin based on the current reactive power output and maximum reactive power output capacity of each wind turbine. Calculate the required reactive power compensation based on the voltage drop, the grid connection point equivalent reactance, and the maximum reactive power output capacity of the SVC. Calculate the reactive power distribution coefficient based on the total number of wind turbines and the reactive power margin of each wind turbine.

[0010] Step 3: Calculate the wind turbine reactive power adjustment based on the reactive power currently output by the SVC, the required reactive power compensation, and the current reactive power output of each wind turbine. Preset the SVC reactive power compensation coefficient. Calculate the SVC initial compensation based on the SVC reactive power compensation coefficient and the voltage drop.

[0011] Step 4: Calculate the wind turbine reactive compensation using the SVC initial compensation and the required reactive compensation. Calculate the adjusted reactive output of each wind turbine using the reactive distribution coefficient and the wind turbine reactive compensation, and iteratively optimize the reactive distribution.

[0012] Furthermore, the method for collecting the bus voltage and the wind farm grid connection point voltage in real time to calculate the voltage drop is as follows:

[0013] Real-time collection of wind farm bus voltage and wind farm grid connection point voltage, calculation of voltage drop:

[0014] ΔV sag =V nom -min(V bus , V grid )

[0015] Where V nom Indicates the rated voltage of the wind farm, V bus Indicates the bus voltage of the wind farm, V grid Indicates the grid-connected voltage of the wind farm, ΔV sag Indicates the voltage drop.

[0016] Furthermore, when the voltage drop exceeds the set voltage drop threshold, the method for limiting the active power output of the non-faulty wind turbine is:

[0017] First, set the voltage drop threshold:

[0018] V thresh =k thresh Vnom

[0019] Where k thresh Indicates the rated factor, V thresh Indicates the voltage drop threshold, where 0.05 <k thresh <0.1, when ΔV sag >V thresh , and the duration exceeds 50ms, it is determined that a voltage drop fault occurs;

[0020] The short-circuit current detection method is used to locate the faulty fan. The output current of a fan is set to I i , where i = 1, 2, ..., z0, represents the index of the wind turbine in the wind farm, z0 represents the total number of wind turbines, and the short-circuit current threshold is set to I fault , when I i >I fault When , it is determined that fan i has failed;

[0021] Limit the active power output of the non-faulty fans and calculate the adjustment factor:

[0022]

[0023] Where k P represents the adjustment factor, k P，min Represents the minimum constraint threshold, and 0 <k P，min <1;

[0024] Limit the active power output of non-faulty wind turbines:

[0025] P i ′=k P P i

[0026] Where, P i Indicates the current active output of each non-faulty wind turbine, P i ′ indicates limiting the active power output of non-faulty fans.

[0027] Furthermore, the method for calculating the reactive margin, the required reactive compensation amount and the reactive distribution coefficient is:

[0028] The reactive power margin is calculated using the current reactive power output of each wind turbine and the maximum reactive power output capacity of each wind turbine:

[0029] Q margin，i =Q max，i -Q i

[0030] Where Q max，i represents the maximum reactive power output capacity of the i-th wind turbine, Q i represents the reactive output of the i-th wind turbine, Q margin，irepresents the reactive power margin of the i-th wind turbine, that is, the additional reactive power that can be provided. At the same time, the reactive power margin of the faulty wind turbine is set to 0;

[0031] Record the equivalent reactance of the grid connection point, the maximum reactive compensation capacity of the SVC, and calculate the required reactive compensation:

[0032]

[0033] Where, X eq Indicates the equivalent reactance of the grid connection point, Q SVC，max Indicates the maximum reactive power compensation capacity of SVC, Q req Indicates the required reactive compensation amount;

[0034] Finally, the reactive power sharing coefficient is calculated based on the total number of wind turbines and the reactive power margin of each wind turbine:

[0035]

[0036] Where, Represents the sum of reactive power margins of all wind turbines, Q margin，i represents the reactive power margin of the i-th wind turbine, α i represents the reactive power distribution coefficient of the i-th wind turbine.

[0037] Furthermore, the method for calculating the wind turbine reactive power adjustment based on the reactive power currently output by the SVC, the required reactive power compensation amount, and the current reactive power output of each wind turbine is as follows:

[0038] Extract the reactive power currently output by the SVC and the required reactive compensation amount, and calculate the overall wind turbine reactive adjustment amount:

[0039] Q wind，req =Q req -Q SVC，current

[0040] Where Q req Indicates the required reactive compensation amount, Q SVC，current Indicates the reactive power currently output by SVC, Q wind，req Indicates the overall wind turbine reactive adjustment, that is, the reactive compensation amount that the wind turbines in the wind farm need to bear;

[0041] Afterwards, the reactive power adjustment of the i-th wind turbine is calculated:

[0042] ΔQ i =min(α i Q wind，req , Q margin，i )

[0043] Where ΔQ i It represents the reactive power adjustment of the i-th fan, that is, the reactive power that needs to be adjusted for the i-th fan.

[0044] Furthermore, the method for calculating the wind turbine reactive compensation amount through the SVC initial compensation amount and the required reactive compensation amount is:

[0045] Pre-set SVC reactive compensation coefficient K SVC , and 0.5 <K SVC <2, extract voltage drop ΔV sag , calculate the initial SVC compensation:

[0046] Q SVC，initial =K SVC ΔV sag

[0047] Where Q SVC，initial Indicates the initial compensation amount of SVC;

[0048] Extract the initial SVC compensation Q SVC，initial And the required reactive compensation Q req , calculate the reactive compensation amount of the fan:

[0049] Q wind，sup =Q req -Q SVC，initial

[0050] Where Q req Indicates the required reactive compensation amount, Q wind，sup Indicates the reactive power compensation amount of the wind turbine, that is, the additional reactive power compensation amount that the wind turbines in the wind farm need to provide.

[0051] Furthermore, the method for calculating the adjusted reactive output of each wind turbine using the reactive power distribution coefficient and the wind turbine reactive power compensation is as follows:

[0052] Calculate the reactive power supplement of each wind turbine:

[0053] ΔQ adj，i =α i Q wind，sup

[0054] Where ΔQ adj，i Indicates the reactive power supplement amount that needs to be adjusted for the i-th wind turbine;

[0055] Then the reactive output of the i-th wind turbine after adjustment is:

[0056] Q new，i =min(Q max，i , Q i +ΔQ adj，i )

[0057] Where Q new，i It represents the adjusted reactive output of the i-th wind turbine, that is, the reactive output of the i-th wind turbine after adjustment.

[0058] Furthermore, the method for iterative optimization of reactive power distribution is:

[0059] Monitor the reactive output Q of the i-th wind turbine after adjustment new，i and the maximum reactive power output capacity Q of the i-th wind turbine max，i The comparison results show that when Q new，i >Q max，i When , it is determined that the i-th wind turbine has reached the upper limit of reactive power output, and the other wind turbines are marked as wind turbines with room for adjustment, and the reactive power output is redistributed:

[0060] First, calculate the reactive power beyond the maximum output:

[0061] Q exceed，i =max(0,Q new，i -Q max，i )

[0062] Where Q exceed，i Indicates the reactive power of the i-th wind turbine that exceeds the maximum output;

[0063] Calculate the total reactive power margin of the new wind turbine:

[0064]

[0065] Where S represents the set of fans that still have room for adjustment, Q margin，new Indicates the total reactive power margin of the new wind turbine, Q margin，i represents the reactive power margin of the i-th wind turbine;

[0066] Recalculate the reactive power distribution coefficient:

[0067]

[0068] Where, α i new represents the reactive power distribution coefficient of the new i-th wind turbine;

[0069] Finally, redistribute the excess reactive power:

[0070]

[0071] Where Q exceed，j represents the reactive power of the jth wind turbine that exceeds its maximum reactive power output capacity, represents the reactive power exceeding the upper limit that needs to be adjusted for the i-th wind turbine, i.e., the new reactive power supplement amount that needs to be adjusted, where j = 1, 2, ... z1, represents the number of the wind turbine that exceeds the maximum reactive power output capacity, and z1 represents the total number of wind turbines that exceed the maximum reactive power output capacity;

[0072] Finally, the adjusted reactive power output of the new i-th wind turbine is calculated as:

[0073]

[0074] Where, represents the reactive power output of the new i-th wind turbine after adjustment;

[0075] When there are still wind turbines with reactive power output greater than their maximum reactive power output capacity, all steps from the beginning of monitoring are repeated until the reactive power output of all wind turbines does not exceed their maximum reactive power output capacity.

[0076] The present invention further provides a wind farm reactive power coordination device, which is used to execute the above-mentioned wind farm reactive power coordination method, including:

[0077] The voltage drop monitoring module is used to collect bus voltage and wind farm grid connection point voltage in real time to calculate the voltage drop. When the voltage drop exceeds the set voltage drop threshold, the active power output of non-faulty wind turbines is limited.

[0078] The reactive margin allocation module is used to calculate the reactive margin based on the current reactive output and maximum reactive output capacity of each wind turbine, calculate the required reactive compensation based on the voltage drop, the equivalent reactance of the grid connection point, and the maximum reactive output capacity of the SVC, and calculate the reactive allocation coefficient based on the total number of wind turbines and the reactive margin of each wind turbine;

[0079] The collaborative compensation calculation module is used to calculate the wind turbine reactive adjustment amount based on the reactive power currently output by the SVC, the required reactive compensation amount, and the current reactive output of each wind turbine. The SVC reactive compensation coefficient is pre-set, and the initial SVC compensation amount is calculated based on the SVC reactive compensation coefficient and the voltage drop amount.

[0080] The dynamic adjustment iteration module is used to calculate the wind turbine reactive compensation amount through the SVC initial compensation amount and the required reactive compensation amount, calculate the adjusted reactive output of each wind turbine using the reactive distribution coefficient and the wind turbine reactive compensation amount, and iteratively optimize the reactive distribution.

[0081] The present invention further provides a storage medium storing a computer program, wherein the computer program implements the above-mentioned wind farm reactive power coordination method when executed by a processor.

[0082] Compared with the prior art, the present invention has the following beneficial effects:

[0083] By real-time monitoring of busbar and grid connection point voltages, voltage drops can be quickly identified and active power restrictions can be triggered, providing resource guarantees for subsequent reactive power output. Then, based on the reactive power margin of the wind turbine, that is, the difference between the current output and the maximum capacity, the reactive power distribution coefficient is dynamically calculated to ensure that wind turbines with large reactive power margins take on more tasks, avoid local overloads, reduce the risk of long-term full-load operation of SVCs, and iterate and optimize reactive power distribution in real time to further ensure that the reactive power output of the wind turbine is always within a safe range. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 Schematic diagram of the overall method flow of the present invention;

[0085] Figure 2 This is the reactive power distribution coefficient diagram of the fan of the present invention;

[0086] Figure 3 This is the reactive power adjustment diagram before and after the fan is adjusted;

[0087] Figure 4 This is a diagram showing the distribution change of the excess weight of the fan of the present invention;

[0088] Figure 5 Schematic diagram of the overall device module of the present invention. DETAILED DESCRIPTION

[0089] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0090] It should be noted that, unless otherwise defined, the technical or scientific terms used in the present invention should have the usual meanings understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0091] Example:

[0092] See also Figures 1 to 4 , the present invention provides a technical solution:

[0093] The wind farm reactive power coordination method includes the following specific steps:

[0094] Step 1: Real-time data collection of bus voltage and wind farm grid connection point voltage is used to calculate voltage drop. When the voltage drop exceeds the set voltage drop threshold, the active power output of the non-faulty wind turbines is restricted.

[0095] Install high-precision voltage sensors at the wind farm busbar and grid connection point, i.e., at the booster station outlet, to collect real-time data on the wind farm busbar voltage and the wind farm grid connection point voltage, and calculate the voltage drop:

[0096] ΔV sag =V nom -min(V bus , V grid )

[0097] Where V nom Indicates the rated voltage of the wind farm, V bus Indicates the bus voltage of the wind farm, V grid Indicates the voltage at the wind farm grid connection point, ΔV sag Indicates the voltage drop. The minimum value of the busbar and grid connection point voltage is taken to ensure that the most serious voltage drop is captured. Due to short-term fluctuations or abnormal faults, min (V bus , V grid ) may have abnormal values, and the transient process of short-term voltage fluctuations usually decays within 1 to 3 power frequency cycles. According to industry experience, a voltage drop of 10% and a duration of 50ms can effectively distinguish between short-term voltage fluctuations and continuous faults. Therefore, when min(V bus , V grid )<0.9V nom Or when the continuous time is less than 50ms, the min(V bus , V grid ) value, excluding accidental fluctuations.

[0098] Set the voltage drop threshold:

[0099] V thresh =k thresh V nom

[0100] Where k thresh Indicates the rated coefficient, that is, the maximum allowable voltage drop ratio, V thresh Indicates the voltage drop threshold. The voltage drop threshold is dynamically adjusted according to the strength of the power grid. When the power grid strength is stronger, the short-circuit capacity is larger and the voltage support capability is stronger, the allowable voltage drop threshold can be appropriately relaxed. On the contrary, a weak power grid needs to set a stricter threshold to quickly trigger the protection action. Among them, 0.05 <k thresh <0.1, the default setting is k thresh =0.1, that is, a 10% rated voltage drop occurs, which meets the monitoring threshold of the power system voltage sag regulations. When the power electronic equipment inside the wind turbine, such as the converter and capacitor, is damaged due to overcurrent or overheating, it will cause a voltage drop. Therefore, when ΔV sag >V thresh , and the duration exceeds 50ms, it is determined that a voltage drop fault occurs;

[0101] In order to ensure the response speed and reliability, the short-circuit current detection method is used to locate the faulty fan, and the output current of a fan is set to I i , where i = 1, 2, ..., z0, represents the index of the wind turbine in the wind farm, z0 represents the total number of wind turbines, and the short-circuit current threshold is set to I fault , when I i >I fault When , it is determined that fan i has failed;

[0102] Limiting the active power output of non-faulty wind turbines, that is, reducing the active power absorbed by the wind turbines from the grid, can alleviate the power shortage of the grid and reduce the risk of further voltage drops. First, calculate the adjustment factor:

[0103]

[0104] Where k P represents the adjustment factor, k P，min Represents the minimum constraint threshold, and 0 <k P，min <1,k P，min The value of k is set based on the technical parameters provided by the wind turbine manufacturer and the actual operating constraints. For example, the minimum active output ratio specified in the manufacturer's technical manual of a wind turbine requires that the active output must be no less than 70% of the rated value, that is, k is set to P，min =0.7, which can ensure that the fan can maintain a relatively stable operating state under the condition of active power limitation, and avoid damage to the fan equipment due to low active power output. If the voltage drop is small, k P The value of k is close to 1. At this time, the active power output of the non-faulty wind turbine after limitation will be close to the active power output of the current non-faulty wind turbine, ensuring that the wind farm can still have a high active power output when the fault is relatively minor and maintain a certain power generation efficiency. If the voltage drop is large, k P The value of will be far away from 1. Severe voltage drop will cause a sharp increase in the reactive power demand of the power grid. By reducing the active power output of the wind turbine, more capacity can be released for reactive power output, helping the power grid to restore voltage stability.

[0105] Limit the active power output of non-faulty wind turbines:

[0106] P i ′=k P P i

[0107] Where, P i represents the active power output of the current i-th non-faulty wind turbine, P i ' indicates limiting the active power output of non-faulty wind turbines. This is because if the active power output is limited too low, the wind turbine may enter an unstable operating state. For example, the blades of the wind turbine may experience increased vibration, the pitch system may become difficult to control, and it may even cause the wind turbine to go offline.

[0108] Step 2: Calculate the reactive power margin based on the current reactive power output and maximum reactive power output capacity of each wind turbine. Calculate the required reactive power compensation based on the voltage drop, the grid connection point equivalent reactance, and the maximum reactive power output capacity of the SVC. Calculate the reactive power distribution coefficient based on the total number of wind turbines and the reactive power margin of each wind turbine.

[0109] The wind farm's monitoring system, such as a SCADA system, collects reactive power output data from each wind turbine in real time. This system continuously monitors the turbine's electrical parameters, recording and transmitting reactive power data at a certain sampling frequency, such as once per second. The maximum reactive power output capacity of each wind turbine is usually provided by the wind turbine manufacturer, such as in the equipment's technical manual or product specifications.

[0110] The reactive power margin is calculated using the current reactive power output of each wind turbine and the maximum reactive power output capacity of each wind turbine:

[0111] Q margin，i =Q max，i -Q i

[0112] Where Q max，i represents the maximum reactive power output capacity of the i-th wind turbine, Q i represents the reactive output of the i-th wind turbine, Q margin，i represents the reactive margin of the i-th wind turbine, that is, the additional reactive power that can be provided. At the same time, the reactive margin of the faulty wind turbine is set to 0, so that the reactive output of the faulty wind turbine does not undergo additional adjustment and maintains the current state. The compensation task is undertaken by the SVC and the non-faulty wind turbines. Different wind turbines have different reactive output states under different operating conditions. By calculating the reactive margin, we can intuitively understand how much additional reactive power each wind turbine can currently provide.

[0113] Record the equivalent reactance X of the grid connection point eq , which can be obtained by grid short-circuit titration:

[0114]

[0115] Where S sc It indicates the short-circuit capacity of the grid connection point. The short-circuit capacity of the grid connection point can be obtained from relevant technical data such as substation design data, equipment technical manuals, and power system operation manuals. When the voltage drops, the grid needs to inject reactive power to support the voltage, and the required reactive power compensation is proportional to the equivalent reactance X of the grid connection point. eq Inversely proportional;

[0116] Extract the maximum reactive power compensation capacity of SVC and calculate the required reactive power compensation:

[0117]

[0118] Where, X eq Indicates the equivalent reactance of the grid connection point, Q SVC，max Indicates the maximum reactive power compensation capacity of SVC, Q req Indicates the required reactive power compensation amount. When a voltage drop occurs in the power system, reactive power needs to be quickly injected through a reactive power compensation device such as SVC to support the voltage. According to the relationship between voltage drop and equivalent reactance, This item represents the reactive power required to restore the voltage theoretically, the maximum reactive power compensation capacity of SVC Q SVC，max This is the physical limitation of the device itself. By taking the minimum value between the theoretical value and the device capability, we ensure that the compensation solution meets the voltage support requirements while staying within the safety range of the device.

[0119] Finally, the reactive power sharing coefficient is calculated based on the total number of wind turbines and the reactive power margin of each wind turbine:

[0120]

[0121] Where, Represents the sum of reactive power margins of all wind turbines, Q margin，i represents the reactive power margin of the i-th wind turbine, α i represents the reactive power distribution coefficient of the i-th wind turbine. This proportional distribution ensures that each wind turbine assumes the reactive power compensation task according to its own residual capacity, avoiding overload of some wind turbines while other wind turbines still have excessive reactive power margin. Table 1 shows the statistical table of the parameters and reactive power distribution coefficients of 40 wind turbines, among which there are 3 faulty wind turbines. Since the margin of the faulty wind turbines is 0, they participate in the calculation but do not actually participate in the distribution.

[0122]

[0123]

[0124] Table 1 Reactive margin statistics

[0125] like Figure 2 As shown in the figure, when wind turbines numbered 10, 20, and 30 fail, the reactive margin and reactive distribution coefficient of each wind turbine change with the wind turbine number. The reactive margin is represented by black dots, and the reactive distribution coefficient is represented by red dots. It can be seen that the reactive margin of most wind turbines fluctuates between 0.4 and 0.5 Mvar, showing a relatively regular fluctuation. The faulty wind turbine does not participate in the reactive distribution logic, so the reactive margin drops sharply to 0, making its reactive distribution coefficient also 0. This has the significance of reasonably allocating reactive power and improving the stability of the power system and the power quality.

[0126] Step 3: Calculate the wind turbine reactive power adjustment based on the reactive power currently output by the SVC, the required reactive power compensation, and the current reactive power output of each wind turbine. Preset the SVC reactive power compensation coefficient. Calculate the SVC initial compensation based on the SVC reactive power compensation coefficient and the voltage drop.

[0127] As a fast-response device, SVC is a centralized reactive power compensation device for the entire wind farm. It maintains the grid-connected point voltage near the rated value and takes priority in undertaking part of the reactive power compensation task. Therefore, the remaining part needs to be shared by the wind turbines, making full use of the complementary characteristics of the two, that is, the SVC has a fast response and the wind turbine has a large capacity.

[0128] The reactive power currently output by the SVC is extracted from the device in real time, and the required reactive power compensation is calculated. Based on the two, the overall wind turbine reactive power adjustment is calculated:

[0129] Q wind，req =Q req -Q SVC，current

[0130] Where Q req Indicates the required reactive compensation amount, Q SVC，current Indicates the reactive power currently output by SVC, Q wind，req Indicates the overall wind turbine reactive adjustment, that is, the reactive compensation amount that the wind farm wind turbines need to bear. It tracks the changes in SVC output in real time and automatically adjusts the wind turbine compensation amount according to the changes, thereby adapting to the dynamic changes in grid conditions and maintaining the stability of system operation.

[0131] Afterwards, the reactive power adjustment of the i-th wind turbine is calculated:

[0132] ΔQ i =min(α i Q wind，req , Q margin，i )

[0133] Where ΔQ i represents the reactive power adjustment of the i-th fan, that is, the reactive power that needs to be adjusted for the i-th fan, where Q margin，i represents the reactive power margin of the i-th wind turbine. If the allocated adjustment exceeds this value, it may cause the wind turbine to overload or exceed its design capacity, shortening the equipment life or even causing failure. Therefore, it is necessary to ensure that the adjustment does not exceed the upper limit of the reactive power margin.

[0134] Pre-set SVC reactive compensation coefficient K SVC , and 0.5 <K SVC <2. In this range, it can prevent the SVC reactive power compensation coefficient K from being too small, which leads to insufficient compensation and inability to effectively support the voltage. It can also prevent the SVC output from exceeding its rated capacity or causing the voltage to rise too quickly due to the coefficient being too large. SVC, which can flexibly match the compensation requirements of different scenarios;

[0135] Extract voltage drop ΔV sag , calculate the initial SVC compensation:

[0136] Q SVC，initial =K SVC ΔV sag

[0137] Where Q SVC，initial Indicates the initial compensation amount of the SVC. This is a quick response value at the initial stage of a fault. When the SVC detects a voltage drop, it gives priority to providing basic reactive power to prevent further voltage deterioration.

[0138] Extract the initial SVC compensation Q SVC，initial And the required reactive compensation Q req , calculate the reactive compensation amount of the fan:

[0139] Q wind，sup =Q req -Q SVC，initial

[0140] Where Q req Indicates the required reactive compensation amount, Q wind，sup Indicates the reactive compensation amount of the wind turbine, that is, the reactive compensation amount that the wind turbine in the wind farm needs to provide additionally. It indicates that if the initial compensation amount of the SVC is not enough to meet the required reactive compensation amount Q req , the wind farm needs to supplement the remaining reactive power compensation through wind turbines to achieve the purpose of rapid response and precise regulation.

[0141] Step 4: Calculate the wind turbine reactive compensation using the SVC initial compensation and the required reactive compensation. Calculate the adjusted reactive output of each wind turbine using the reactive distribution coefficient and the wind turbine reactive compensation, and iteratively optimize the reactive distribution.

[0142] Calculate the reactive power supplement of each wind turbine:

[0143] ΔQ adj，i =α i Q wind，sup

[0144] Where ΔQ adj，i The reactive power supplement amount that needs to be adjusted for the i-th wind turbine is calculated and distributed to each wind turbine in proportion to its own residual reactive power margin to avoid overloading of a single wind turbine.

[0145] Then the reactive output of the i-th wind turbine after adjustment is:

[0146] Q new，i =min(Q max，i , Q i +ΔQ adj，i )

[0147] Where Q new，i It represents the adjusted reactive output of the i-th wind turbine, that is, the reactive output after adjustment of the i-th wind turbine, and the maximum reactive output capacity Q of the i-th wind turbine max，i This ensures that the fan can provide reactive power within a safe range, further avoiding fan overload.

[0148] Table 2 shows that after the reactive margin is calculated using the maximum reactive output capacity and the current reactive power, the reactive distribution coefficient is calculated using the above formula based on the total number of wind turbines and the reactive margin of each wind turbine, thereby obtaining the reactive power adjustment amount and adjusted reactive power of each wind turbine.

[0149]

[0150]

[0151]

[0152] Table 2 Statistics of fan reactive power adjustment

[0153] like Figure 3 As shown in the figure, the reactive power before adjustment, the reactive power adjustment amount and the reactive power after adjustment of each wind turbine are all unchanged except for the reactive power of the faulty wind turbine. The reactive power of the non-faulty wind turbines increases to varying degrees, which is consistent with the concept that faults may cause system voltage fluctuations and require more reactive power support. Figure 3 It can be intuitively concluded that after adjustment, the reactive power of the non-faulty wind turbines does not exceed their maximum reactive output capacity, leaving a safe reactive margin, avoiding the need to coordinate with the SVC to supplement reactive power in the event of overload of a single wind turbine, and balancing the use of overall reactive resources.

[0154] At the same time, real-time monitoring of the reactive output Q of the i-th wind turbine after adjustment new，i and the maximum reactive power output capacity Q of the i-th wind turbine max，i The comparison results show that when Q new，i >Q max，i When , it is determined that the i-th wind turbine has reached the upper limit of reactive power output. This is because when reactive power is first distributed based on the reactive power distribution coefficient, the maximum reactive power output capacity of each wind turbine is not immediately limited. Therefore, during the reactive power compensation process, the reactive power output of the wind turbine must be limited to its maximum reactive power output capacity Q max，i , exceeding this value means that further compensation is impossible. At this time, the remaining reactive power demand needs to be reallocated to other wind turbines with reactive power margin to ensure the realization of the overall compensation target.

[0155] Mark the other wind turbines as wind turbines with room for adjustment and redistribute reactive power output:

[0156] First, calculate the reactive power beyond the maximum output:

[0157] Q exceed，i =max(0,Q new，i -Q max，i )

[0158] Where Q exceed，i Indicates the reactive power of the i-th wind turbine that exceeds the maximum output;

[0159] Calculate the total reactive power margin of the new wind turbine:

[0160]

[0161] Where S represents the set of fans that still have room for adjustment, Q margin，new Indicates the total reactive power margin of the new wind turbine, Q margin，i represents the reactive power margin of the i-th wind turbine. Wind turbines with room for adjustment are still capable of undertaking additional reactive power compensation tasks, and the new total reactive power margin of wind turbines reflects the remaining available reactive power regulation resources.

[0162] Recalculate the reactive power distribution coefficient:

[0163]

[0164] Where, α i new The reactive power distribution coefficient of the new i-th wind turbine is the ratio of its own reactive power margin to the total reactive power margin of the new wind turbine, ensuring fair and efficient distribution, so that wind turbines with large reactive power margins can take on more tasks and avoid local overload.

[0165] Finally, redistribute the excess reactive power:

[0166]

[0167] Where Q exceed，j represents the reactive power of the jth wind turbine that exceeds its maximum reactive power output capacity, represents the reactive power exceeding the upper limit that needs to be adjusted for the i-th wind turbine, i.e., the new reactive power supplement amount that needs to be adjusted, where j = 1, 2, ... z1, represents the number of the wind turbine that exceeds the maximum reactive power output capacity, and z1 represents the total number of wind turbines that exceed the maximum reactive power output capacity;

[0168] Finally, the adjusted reactive power output of the new i-th wind turbine is calculated as:

[0169]

[0170] Where, represents the reactive power output of the new i-th wind turbine after adjustment;

[0171] Check the new adjusted reactive output of all fans If there are still wind turbines with a reactive output greater than their maximum reactive output capacity, all steps from the beginning of the monitoring are repeated until the reactive output of all wind turbines does not exceed their maximum reactive output capacity. Since the total margin is limited, the number of iterations is limited and converges. Table 3 shows that when reactive power is first distributed based on the reactive power distribution coefficient, the wind turbine reaches the reactive output upper limit and cannot meet the adjusted reactive output obtained by direct calculation. It is necessary to finally adjust to its own maximum reactive output and redistribute the excess reactive power. After summarizing, a data table is generated.

[0172]

[0173]

[0174] Table 3 Reactive power excess reallocation table

[0175] like Figure 4 As shown in the figure, wind turbines 10, 20, and 30 are faulty, and the initial adjustment amount is 0. Among the non-faulty wind turbines, the adjustment amount of the wind turbine with a margin of 0.5 Mvar is set to 0.502 Mvar, and the adjustment amount of the wind turbine with a margin of 0.45 Mvar is set to 0.452 Mvar. However, the reactive power of 25 wind turbines exceeds the upper limit after adjustment. For example, the reactive power of wind turbine 1 is initially adjusted to 0.802 Mvar, which is higher than its maximum reactive output capacity. After redistribution, the reactive power reaches its maximum reactive output capacity. Then, by redistributing the remaining reactive power demand and through multiple iterative allocations, the maximum possible reactive power compensation is finally achieved within the safety range of the wind turbines, avoiding overload of the wind turbine converter or motor due to reactive power compensation.

[0176] See also Figure 5 The present invention further provides a wind farm reactive power coordination method, device, and storage medium for executing the above-mentioned wind farm reactive power coordination method, including:

[0177] The voltage drop monitoring module is used to collect bus voltage and wind farm grid connection point voltage in real time to calculate the voltage drop. When the voltage drop exceeds the set voltage drop threshold, the active power output of non-faulty wind turbines is limited.

[0178] The reactive margin allocation module is used to calculate the reactive margin based on the current reactive output and maximum reactive output capacity of each wind turbine, calculate the required reactive compensation based on the voltage drop, the equivalent reactance of the grid connection point, and the maximum reactive output capacity of the SVC, and calculate the reactive allocation coefficient based on the total number of wind turbines and the reactive margin of each wind turbine;

[0179] The collaborative compensation calculation module is used to calculate the wind turbine reactive adjustment amount based on the reactive power currently output by the SVC, the required reactive compensation amount, and the current reactive output of each wind turbine. The SVC reactive compensation coefficient is pre-set, and the initial SVC compensation amount is calculated based on the SVC reactive compensation coefficient and the voltage drop amount.

[0180] The dynamic adjustment iteration module is used to calculate the wind turbine reactive compensation amount through the SVC initial compensation amount and the required reactive compensation amount, calculate the adjusted reactive output of each wind turbine using the reactive distribution coefficient and the wind turbine reactive compensation amount, and iteratively optimize the reactive distribution.

[0181] The present invention further provides a storage medium storing a computer program, wherein the computer program implements the above-mentioned wind farm reactive power coordination method when executed by a processor.

[0182] The above formulas are all dimensionless and numerical calculations. The formulas are obtained by collecting a large amount of data and performing software simulation to obtain the most recent real situation. The preset parameters in the formulas are set by technicians in this field according to actual conditions.

[0183] The above embodiments can be implemented in whole or in part by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software depends on the specific application and design constraints of the technical solution.

[0184] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, and may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment as needed.

[0185] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.

Claims

1. A wind farm reactive power coordination method, characterized in that: The specific steps include: Step 1: Real-time data collection of bus voltage and wind farm grid connection point voltage is used to calculate voltage drop. When the voltage drop exceeds the set voltage drop threshold, the active power output of the non-faulty wind turbines is restricted. Step 2: Calculate the reactive power margin based on the current reactive power output and maximum reactive power output capacity of each wind turbine. Calculate the required reactive power compensation based on the voltage drop, the grid connection point equivalent reactance, and the maximum reactive power output capacity of the SVC. Calculate the reactive power distribution coefficient based on the total number of wind turbines and the reactive power margin of each wind turbine. Step 3: Calculate the wind turbine reactive power adjustment based on the reactive power currently output by the SVC, the required reactive power compensation, and the current reactive power output of each wind turbine. Preset the SVC reactive power compensation coefficient. Calculate the SVC initial compensation based on the SVC reactive power compensation coefficient and the voltage drop. Step 4: Calculate the wind turbine reactive compensation using the SVC initial compensation and the required reactive compensation. Calculate the adjusted reactive output of each wind turbine using the reactive distribution coefficient and the wind turbine reactive compensation, and iteratively optimize the reactive distribution.

2. The wind farm reactive power coordination method according to claim 1, characterized in that: The method for calculating voltage drop by collecting bus voltage and wind farm grid connection point voltage in real time is as follows: Real-time collection of wind farm bus voltage and wind farm grid connection point voltage, calculation of voltage drop: ΔV sag =V nom -min(V bus ,V grid ) Where V nom Indicates the rated voltage of the wind farm, V bus Indicates the bus voltage of the wind farm, V grid Indicates the grid-connected voltage of the wind farm, ΔV sag Indicates the voltage drop.

3. The wind farm reactive power coordination method according to claim 2, characterized in that: When the voltage drop exceeds the set voltage drop threshold, the method for limiting the active power output of non-faulty wind turbines is as follows: First, set the voltage drop threshold: V thresh =k thresh V nom Where k thresh Indicates the rated factor, V thresh Indicates the voltage drop threshold, where 0.05 <k thresh <0.1, when ΔV sag >V thresh , and the duration exceeds 50ms, it is determined that a voltage drop fault occurs; The short-circuit current detection method is used to locate the faulty fan. The output current of a fan is set to I i , where i = 1, 2, ..., z0, represents the index of the wind turbine in the wind farm, z0 represents the total number of wind turbines, and the short-circuit current threshold is set to I fault , when I i >I fault When , it is determined that fan i has failed; Limit the active power output of the non-faulty fans and calculate the adjustment factor: Where k P represents the adjustment factor, k P，min Represents the minimum constraint threshold, and 0 <k P，min <1; Limit the active power output of non-faulty fans: P i ′=k P P i Where, P i Indicates the current active output of each non-faulty wind turbine, P i ′ indicates limiting the active power output of non-faulty fans.

4. The wind farm reactive power coordination method according to claim 1, characterized in that: The method for calculating reactive power margin, required reactive power compensation and reactive power distribution coefficient is: The reactive power margin is calculated using the current reactive power output of each wind turbine and the maximum reactive power output capacity of each wind turbine: Q margin，i =Q max，i -Q i Where Q max，i represents the maximum reactive power output capacity of the i-th wind turbine, Q i represents the reactive power output of the i-th wind turbine, Q margin，i represents the reactive power margin of the i-th wind turbine, that is, the additional reactive power that can be provided. At the same time, the reactive power margin of the faulty wind turbine is set to 0; Record the equivalent reactance of the grid connection point, the maximum reactive compensation capacity of the SVC, and calculate the required reactive compensation: Where, X eq Indicates the equivalent reactance of the grid connection point, Q SCC，max Indicates the maximum reactive power compensation capacity of SVC, Q req Indicates the required reactive compensation amount; Finally, the reactive power sharing coefficient is calculated based on the total number of wind turbines and the reactive power margin of each wind turbine: Where, i Represents the sum of reactive power margins of all wind turbines, Q margin，i represents the reactive power margin of the i-th wind turbine, α i represents the reactive power distribution coefficient of the i-th wind turbine.

5. The wind farm reactive power coordination method according to claim 4, characterized in that: The method for calculating the wind turbine reactive power adjustment based on the reactive power currently output by the SVC, the required reactive power compensation, and the current reactive power output of each wind turbine is as follows: Extract the reactive power currently output by the SVC and the required reactive compensation amount, and calculate the overall wind turbine reactive adjustment amount: Q wind，req =Q req -Q SVC，current Where Q req Indicates the required reactive compensation amount, Q SVC，current Indicates the reactive power currently output by SVC, Q wind，req Indicates the overall wind turbine reactive adjustment, that is, the reactive compensation amount that the wind turbines in the wind farm need to bear; Afterwards, the reactive power adjustment of the i-th wind turbine is calculated: ΔQ i =min(α i ·Q wind，req ,Q margin，i ) Where ΔQ i It represents the reactive power adjustment of the i-th fan, that is, the reactive power that needs to be adjusted for the i-th fan.

6. The wind farm reactive power coordination method according to claim 2, characterized in that: The method for calculating the wind turbine reactive compensation amount through the SVC initial compensation amount and the required reactive compensation amount is: Pre-set SVC reactive compensation coefficient K SVC , and 0.5 <K SVC <2, extract voltage drop ΔV sag , calculate the initial SVC compensation: Q SVC，initial =K SVC ·ΔV sag Where Q SVC，initial Indicates the initial compensation amount of SVC; Extract the initial SVC compensation Q SVC，initial And the required reactive compensation Q req , calculate the reactive compensation amount of the fan: Q wind，sup =Q req -Q SVC，initial Where Q req Indicates the required reactive compensation amount, Q wind，sup Indicates the reactive power compensation amount of the wind turbine, that is, the additional reactive power compensation amount that the wind turbines in the wind farm need to provide.

7. The wind farm reactive power coordination method according to claim 6, characterized in that: The method for calculating the adjusted reactive output of each wind turbine using the reactive distribution coefficient and the reactive compensation amount of the wind turbine is: Calculate the reactive power supplement of each wind turbine: ΔQ adj，i =α i ·Q wind，sup Where ΔQ adj，i Indicates the reactive power supplement amount that needs to be adjusted for the i-th wind turbine; Then the reactive output of the i-th wind turbine after adjustment is: Q new，i =min(Q max，i ,Q i +ΔQ adj，i ) Where Q new，i It represents the adjusted reactive output of the i-th wind turbine, that is, the reactive output of the i-th wind turbine after adjustment.

8. The wind farm reactive power coordination method according to claim 7, characterized in that: The method for iterative optimization of reactive power distribution is: Monitor the reactive output Q of the i-th wind turbine after adjustment new，i and the maximum reactive power output capacity Q of the i-th wind turbine max，i The comparison results show that when Q new，i >Q max，i When , it is determined that the i-th wind turbine has reached the upper limit of reactive power output, and the other wind turbines are marked as wind turbines with room for adjustment, and the reactive power output is redistributed: First, calculate the reactive power beyond the maximum output: Q exceed，i =max(0,Q new，i -Q max，i ) Where Q exceed，i Indicates the reactive power of the i-th wind turbine that exceeds the maximum output; Calculate the total reactive power margin of the new wind turbine: Where S represents the set of fans that still have room for adjustment, Q margin，new Indicates the total reactive power margin of the new wind turbine, Q margin，i represents the reactive power margin of the i-th wind turbine; Recalculate the reactive power distribution coefficient: Where, α i new represents the reactive power distribution coefficient of the new i-th wind turbine; Finally, redistribute the excess reactive power: Where Q exceed，j represents the reactive power of the jth wind turbine that exceeds its maximum reactive power output capacity, represents the reactive power exceeding the upper limit that needs to be adjusted for the i-th wind turbine, i.e., the new reactive power supplement amount that needs to be adjusted, where j = 1, 2, ... z1, represents the number of the wind turbine that exceeds the maximum reactive power output capacity, and z1 represents the total number of wind turbines that exceed the maximum reactive power output capacity; Finally, the adjusted reactive power output of the new i-th wind turbine is calculated as: Where, represents the reactive power output of the new i-th wind turbine after adjustment; When there are still wind turbines with reactive power output greater than their maximum reactive power output capacity, all steps from the beginning of monitoring are repeated until the reactive power output of all wind turbines does not exceed their maximum reactive power output capacity.

9. Wind farm reactive power coordination device, characterized by: The device is used to execute the wind farm reactive power coordination method according to any one of claims 1 to 8: The voltage drop monitoring module is used to collect bus voltage and wind farm grid connection point voltage in real time to calculate the voltage drop. When the voltage drop exceeds the set voltage drop threshold, the active power output of non-faulty wind turbines is limited. The reactive margin allocation module is used to calculate the reactive margin based on the current reactive output and maximum reactive output capacity of each wind turbine, calculate the required reactive compensation based on the voltage drop, the equivalent reactance of the grid connection point, and the maximum reactive output capacity of the SVC, and calculate the reactive allocation coefficient based on the total number of wind turbines and the reactive margin of each wind turbine; The collaborative compensation calculation module is used to calculate the wind turbine reactive adjustment amount based on the reactive power currently output by the SVC, the required reactive compensation amount, and the current reactive output of each wind turbine. The SVC reactive compensation coefficient is pre-set, and the initial SVC compensation amount is calculated based on the SVC reactive compensation coefficient and the voltage drop amount. The dynamic adjustment iteration module is used to calculate the wind turbine reactive compensation amount through the SVC initial compensation amount and the required reactive compensation amount, calculate the adjusted reactive output of each wind turbine using the reactive distribution coefficient and the wind turbine reactive compensation amount, and iteratively optimize the reactive distribution.

10. A storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by the processor, the wind farm reactive power coordination method according to any one of claims 1 to 8 is implemented.

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