Wind and light station fault power control method and device

Abstract

The invention relates to a wind and light field station fault power control method and device. The method comprises the steps of obtaining a current component instruction value of a wind and light field station and a positive and negative sequence voltage phase difference of a common connection point; based on the current component instruction values, the positive and negative sequence voltage phase difference and an over-current limiting threshold value, calculating and judging whether each current component instruction value meets the over-current limiting threshold value or not; when the current component instruction values do not meet the over-current limit threshold value, reactive current component instruction values are subjected to compensation calculation to obtain reactive current component instruction update values, and whether the over-current limit threshold value is met or not is judged again; and when the current component instruction value meets the over-current limit threshold value, performing power decoupling inverse transformation on the current component instruction value and inputting a result into a current control ring to realize power control of the wind and light field station. According to the method, reactive power output of the wind and light station is adjusted in a self-adaptive mode during the fault period, active power is provided, a supporting effect is achieved for frequency stability of the system, and the control flexibility of the wind and light station during the fault period is greatly improved.

Description

Technical Field

[0001] The present application relates to the technical field of fault control of renewable energy electric fields, and in particular to a method and device for controlling fault power of a wind and solar power station. Background Art

[0002] With the increasing proportion of wind power, photovoltaic and other new energy power sources installed and the weak overcurrent characteristics of new energy power electronic equipment, large-scale wind and solar power generation systems are gradually connected to weak power grids. And with the full construction of large-scale wind and solar power generation bases, the number of wind and solar power generation systems connected to weak power grids will continue to increase in the future.

[0003] However, in the process of large-scale wind and solar power grid-connected power generation, the system stability problem and the lack of regulation ability are becoming increasingly prominent. Wind and solar power stations are prone to frequent subsynchronous oscillations in weak power grid scenarios, causing power outages and other accidents, which makes the current wind and solar power generation system have serious problems such as narrow frequency band regulation range, insufficient frequency and voltage support amplitude and regulation speed, and insufficient control flexibility of the current wind and solar power generation system. Summary of the invention

[0004] In order to overcome the above-mentioned deficiencies of the prior art, the present application provides a method and device for controlling power failure of a wind-solar station, which specifically adopts the following technical solutions:

[0005] A method for controlling power failure of a wind-solar station comprises the following steps:

[0006] Obtaining the current component command value of the wind and solar power station and the positive and negative sequence voltage phase difference of the common connection point; wherein the current component command value includes the positive sequence reactive current component command value and the negative sequence reactive current component command value corresponding to the reactive current, and the positive sequence active current component command value and the negative sequence active current component command value corresponding to the active current;

[0007] Based on the current component command value of the wind and solar power station, the positive and negative sequence voltage phase difference of the common connection point and the overcurrent limit threshold, it is calculated and judged whether each current component command value meets the overcurrent limit threshold;

[0008] When it is determined that the current component command value does not meet the overcurrent limit threshold, compensation calculation is performed on the positive-sequence reactive current component command value and the negative-sequence reactive current component command value to obtain a positive-sequence reactive current component command update value and a negative-sequence reactive current component command update value;

[0009] Determine again whether the positive-sequence reactive current component instruction update value and the negative-sequence reactive current component instruction update value meet the overcurrent limit threshold value respectively, until it is determined that the corresponding current component instruction update value meets the overcurrent limit threshold value;

[0010] When it is determined that the current component command value meets the overcurrent limit threshold, a power decoupling inverse transformation is performed on the current component command value to obtain a transformed current component command value;

[0011] The transformed current component command value is input into the current control loop to realize wind and solar power station power control.

[0012] Optionally: the step of obtaining the command values ​​of each current component of the wind and solar power station includes:

[0013] Obtaining an equivalent positive sequence voltage and an equivalent imaginary impedance of the power grid on the opposite side of the common connection point, and obtaining a preset first control strategy setting instruction value;

[0014] The corresponding positive-sequence reactive current component command value is calculated based on the equivalent positive-sequence voltage of the power grid on the opposite side of the common connection point, the equivalent imaginary part of the impedance, and the first control strategy setting command value.

[0015] Optionally: the step of obtaining the command values ​​of each current component of the wind and solar power station includes:

[0016] Obtaining an equivalent negative sequence voltage and an equivalent imaginary impedance of the power grid on the opposite side of the common connection point, and obtaining a preset second control strategy setting instruction value;

[0017] The corresponding negative-sequence reactive current component command value is calculated based on the equivalent negative-sequence voltage of the power grid on the opposite side of the common connection point, the equivalent imaginary part of the impedance, and the second control strategy setting command value.

[0018] Optionally: the step of obtaining the command values ​​of each current component of the wind and solar power station includes:

[0019] Obtain the positive sequence active current component command value output before the fault;

[0020] The positive-sequence active current component command value output before the fault is used as the current positive-sequence active current component command value;

[0021] Set the current negative-sequence active current component command value to zero.

[0022] Optionally: the step of calculating based on the current component command value of the wind and solar power station, the positive and negative sequence voltage phase difference of the common connection point and the overcurrent limit threshold comprises:

[0023] Obtaining a first intermediate current value by calculation according to the positive-sequence active current component command value, the negative-sequence reactive current component command value and the positive- and negative-sequence voltage phase difference of the common connection point;

[0024] A second intermediate current value is obtained by calculating the positive-sequence reactive current component command value, the negative-sequence reactive current component command value and the positive- and negative-sequence voltage phase difference of the common connection point;

[0025] Obtaining a third intermediate current value by calculation according to the positive-sequence reactive current component command value, the negative-sequence reactive current component command value and the positive- and negative-sequence voltage phase difference of the common connection point;

[0026] A fourth intermediate current value is obtained by calculation based on the positive-sequence active current component command value, the negative-sequence reactive current component command value and the positive- and negative-sequence voltage phase difference of the common connection point.

[0027] Optionally: the step of calculating based on the current component command value of the wind and solar power station, the positive and negative sequence voltage phase difference of the common connection point and the overcurrent limit threshold comprises:

[0028] Calculating and obtaining a first calculation result according to the first intermediate current value and the second intermediate current value;

[0029] Obtaining a second calculation result by calculation according to the first intermediate current value, the second intermediate current value, the third intermediate current value, and the fourth intermediate current value;

[0030] A third calculation result is obtained by calculation according to the first intermediate current value, the second intermediate current value, the third intermediate current value, and the fourth intermediate current value.

[0031] Optionally: the step of judging whether each current component command value meets the overcurrent limit threshold comprises:

[0032] When it is determined that at least one of the first calculation result, the second calculation result and the third calculation result is greater than the overcurrent limit threshold corresponding to itself, the determination result is determined to be the first determination result, that is, it is determined that the current component command value does not meet the overcurrent limit threshold;

[0033] When it is determined that the first calculation result, the second calculation result and the third calculation result are all less than or equal to their corresponding overcurrent limiting thresholds, the determination result is determined to be the second determination result, that is, it is determined that the current component command value meets the overcurrent limiting threshold.

[0034] Optionally: the step of performing compensation calculation on the positive sequence reactive current component command value comprises:

[0035] Respectively obtain the equivalent positive sequence voltage and the corresponding equivalent impedance imaginary part of the power grid on the opposite side of the common connection point, and obtain the preset first control strategy setting instruction value and compensation adjustment parameter;

[0036] The first step length is calculated based on the equivalent positive sequence voltage of the power grid on the opposite side of the common connection point, the corresponding equivalent impedance imaginary part, the first control strategy setting command value and the compensation adjustment parameter;

[0037] Calculate the difference between the positive-sequence reactive current component command value and the corresponding first step length, and use the difference result as the positive-sequence reactive current component command update value.

[0038] Optionally: the step of performing compensation calculation on the negative-sequence reactive current component command value comprises:

[0039] Respectively obtain the equivalent negative sequence voltage and the corresponding equivalent impedance imaginary part of the power grid on the opposite side of the common connection point, and obtain the preset second control strategy setting instruction value and compensation adjustment parameter;

[0040] The second step length is obtained by calculation based on the equivalent negative sequence voltage of the power grid on the opposite side of the common connection point, the corresponding equivalent impedance imaginary part, the second control strategy setting command value and the compensation adjustment parameter;

[0041] The difference between the negative-sequence reactive current component command value and the corresponding second step length is calculated, and the difference result is used as the negative-sequence reactive current component command update value.

[0042] Furthermore, the present application also discloses a wind-solar station fault power control device, the device comprising:

[0043] A parameter acquisition module, used to obtain the current component command value of the wind and solar power station and the positive and negative sequence voltage phase difference of the common connection point; wherein the current component command value includes the positive sequence reactive current component command value and the negative sequence reactive current component command value corresponding to the reactive current, and the positive sequence active current component command value and the negative sequence active current component command value corresponding to the active current;

[0044] A parameter calculation module is used to calculate and determine whether each current component command value meets the overcurrent limit threshold based on the current component command value of the wind and solar power station, the positive and negative sequence voltage phase difference of the common connection point and the overcurrent limit threshold;

[0045] A first determination module is used for, when it is determined that the current component command value does not meet the overcurrent limit threshold, respectively performing compensation calculation on the positive-sequence reactive current component command value and the negative-sequence reactive current component command value to obtain a positive-sequence reactive current component command update value and a negative-sequence reactive current component command update value;

[0046] A parameter updating module, used for judging again whether the positive-sequence reactive current component instruction update value and the negative-sequence reactive current component instruction update value meet the overcurrent limit threshold value respectively, until it is determined that the corresponding current component instruction update value meets the overcurrent limit threshold value;

[0047] A second determination module is used to perform a power decoupling inverse transformation on the current component command value to obtain a transformed current component command value when it is determined that the current component command value meets the overcurrent limit threshold;

[0048] The control execution module is used to input the transformed current component command value into the current control loop to realize the power control of the wind and solar power station.

[0049] Beneficial Effects

[0050] The technical solution of this application has the following beneficial effects:

[0051] The wind and solar station fault power control method of the present application can give full play to the reactive power generation resources of the wind and solar station during the fault period, and adaptively adjust the reactive output of the wind and solar station according to the voltage drop and the system short circuit ratio. In addition, the control method can ensure that the wind and solar station outputs a certain active power during the fault period, thereby supporting the frequency stability of the system, thereby overcoming the lack of reactive power control flexibility of the existing wind and solar station and greatly improving the control flexibility of the wind and solar station during the fault period. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a flow chart of the method for controlling power of a wind-solar station fault in an embodiment of the present application.

[0053] Figure 2 This is a schematic diagram of the grid-connected topology structure of a wind-solar station in an embodiment of the present application.

[0054] Figure 3 This is a schematic diagram of the grid-connected control structure of a wind-solar station in an embodiment of the present application.

[0055] Figure 4 The present invention is a flow chart of overcurrent limit determination in the wind-solar station fault power control method in the embodiment of the present application.

[0056] Figure 5 This is a schematic diagram of the comparison of the high and low voltage side voltages of the main transformer at the station grid connection point in the control method of the embodiment of the present application and the current ride-through control standard. Figure 5 a is a schematic diagram of the voltage waveforms on the high and low voltage sides of the main transformer at the grid connection point under the control method of this embodiment; Figure 5 Middle b is a schematic diagram of the voltage waveforms on the high and low voltage sides of the main transformer at the grid connection point under the current ride-through control standard in this embodiment.

[0057] Figure 6 This is a schematic diagram comparing the positive and negative sequence voltages of the station grid connection point in the control method of the present application embodiment and the current ride-through control standard. Figure 6 a is a schematic diagram of positive and negative sequence voltages at the grid connection point of the station under the control method of this embodiment; Figure 6 Figure b is a schematic diagram of the positive and negative sequence voltages at the station grid connection point under the current ride-through control standard.

[0058] Figure 7 This is a schematic diagram comparing the three-phase current waveform output by the station in the control method in the embodiment of the present application with the current ride-through control standard. Figure 7 Figure a is a schematic diagram of the three-phase current waveform output by the station under the control method in this embodiment; Figure 7 Figure b is a schematic diagram of the three-phase current waveform output by the station under the current crossing control standard.

[0059] Figure 8 It is a schematic diagram of the structure of the wind-solar station fault power control device in the embodiment of the present application.

[0060] Fig. 9 This is a structural diagram of an electronic device in an embodiment of the present application. DETAILED DESCRIPTION

[0061] The present application is further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and cannot be used to limit the scope of protection of the present application. It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanation of the present application.

[0062] Combination Figure 1 As shown, the embodiment of the present application specifically discloses a method for controlling power of a wind-solar station fault, which comprises the following steps:

[0063] Step S1: obtaining the current component command value of the wind and solar power station and the positive and negative sequence voltage phase difference of the common connection point (PCC); wherein the current component command value includes a positive sequence reactive current component command value and a negative sequence reactive current component command value corresponding to the reactive current, and a positive sequence active current component command value and a negative sequence active current component command value corresponding to the active current;

[0064] Step S2: Calculate based on the current component command value of the wind and solar power station, the positive and negative sequence voltage phase difference of the common connection point and the overcurrent limit threshold, and determine whether each current component command value meets the overcurrent limit threshold;

[0065] Step S3: when it is determined that the current component command value does not meet the overcurrent limit threshold, respectively performing compensation calculations on the positive-sequence reactive current component command value and the negative-sequence reactive current component command value to obtain a positive-sequence reactive current component command update value and a negative-sequence reactive current component command update value;

[0066] Step S4: determining again whether the positive-sequence reactive current component instruction update value and the negative-sequence reactive current component instruction update value meet the overcurrent limit threshold value, until determining that the corresponding current component instruction update value meets the overcurrent limit threshold value;

[0067] Step S5: When it is determined that the current component command value meets the overcurrent limit threshold, the current component command value is subjected to a power decoupling inverse transformation to obtain a transformed current component command value;

[0068] Step S6: input the transformed current component command value into the current control loop to realize wind and solar power station power control.

[0069] In the above step S1, a device is used to obtain the command values ​​of each current component of the wind and solar power station, and the device can be a computer device for executing the method, and can also be a controller of the grid-side converter of the wind and solar power generation unit.

[0070] Once the station controller of the wind and solar power station detects a fault, it switches to the fault control strategy. At this time, the station starts the online impedance estimator, which can calculate the equivalent positive sequence voltage of the grid on the opposite side of the common connection point (PCC) within 20ms. Equivalent negative sequence voltage And the equivalent impedance R g +jX g ,like Figure 2 shown.

[0071] The station controller of the station collects the three-phase voltage and current at the point of common connection (PCC). The collected three-phase data is input into the Clarke transformation module and decomposed into the αβ coordinate system to obtain the voltage component v of the point of common connection (PCC) in the αβ coordinate system during the fault period. α 、v β And the current component i α 、i β .

[0072] Then v α 、v β 、i α 、i β Input to Park transformation, further transform the AC component v in dq coordinate system α 、v β 、i α 、i β Convert to DC component as well as like Figure 3 As shown, U corresponds to u and I corresponds to i.

[0073] The step of obtaining the current component command values ​​of the wind and solar power stations includes:

[0074] Obtaining an equivalent positive sequence voltage and an equivalent imaginary impedance of the power grid on the opposite side of the common connection point, and obtaining a preset first control strategy setting instruction value;

[0075] The corresponding positive-sequence reactive current component command value is calculated based on the equivalent positive-sequence voltage of the power grid on the opposite side of the common connection point, the equivalent imaginary part of the impedance, and the first control strategy setting command value.

[0076] Furthermore, the step of obtaining the command values ​​of each current component of the wind and solar power station further includes:

[0077] Obtaining an equivalent negative sequence voltage and an equivalent imaginary impedance of the power grid on the opposite side of the common connection point, and obtaining a preset second control strategy setting instruction value;

[0078] The corresponding negative-sequence reactive current component command value is calculated based on the equivalent negative-sequence voltage of the power grid on the opposite side of the common connection point, the equivalent imaginary part of the impedance, and the second control strategy setting command value.

[0079] Based on the above steps, the positive sequence reactive current component command value can be calculated respectively and negative sequence reactive current component command value

[0080]

[0081] in Set the command value for the first control strategy, which can be 0.9pu; Set the command value for the second control strategy, which can be 0.05pu; X g is the imaginary part of equivalent impedance; is the equivalent positive sequence voltage of the power grid on the opposite side of the common connection point; It is the equivalent negative sequence voltage of the power grid on the opposite side of the common connection point.

[0082] Furthermore, the step S1 of obtaining the current component command values ​​of the wind and solar power stations further includes:

[0083] Obtaining the positive-sequence active current component command value output before the fault; and using the positive-sequence active current component command value output before the fault as the current positive-sequence active current component command value;

[0084] Set the current negative-sequence active current component command value to zero.

[0085] It should be noted that in this control method, the positive sequence active current component command value The setting is the same as the output command before the fault to ensure that the wind and solar power station can still output a certain amount of active power during the fault, thereby improving flexibility, and the negative sequence active current component command value Set to 0. That is:

[0086]

[0087] in is the positive sequence active current component command value; It is the positive sequence active current component command value output before the fault; It is the negative sequence active current component command value.

[0088] Then, in step S2, calculation is performed based on the current component command value of the wind and solar power station, the positive and negative sequence voltage phase difference of the common connection point and the overcurrent limit threshold, and the calculation steps include:

[0089] Obtaining a first intermediate current value by calculation according to the positive-sequence active current component command value, the negative-sequence reactive current component command value and the positive- and negative-sequence voltage phase difference of the common connection point;

[0090] A second intermediate current value is obtained by calculating the positive-sequence reactive current component command value, the negative-sequence reactive current component command value and the positive- and negative-sequence voltage phase difference of the common connection point;

[0091] Obtaining a third intermediate current value by calculation according to the positive-sequence reactive current component command value, the negative-sequence reactive current component command value and the positive- and negative-sequence voltage phase difference of the common connection point;

[0092] A fourth intermediate current value is obtained by calculation based on the positive-sequence active current component command value, the negative-sequence reactive current component command value and the positive- and negative-sequence voltage phase difference of the common connection point.

[0093] Furthermore, based on the first intermediate current value, the second intermediate current value, the third intermediate current value and the fourth intermediate current value, further calculation is performed to obtain a calculation result:

[0094] Calculating and obtaining a first calculation result according to the first intermediate current value and the second intermediate current value;

[0095] Obtaining a second calculation result by calculation according to the first intermediate current value, the second intermediate current value, the third intermediate current value, and the fourth intermediate current value;

[0096] A third calculation result is obtained by calculation according to the first intermediate current value, the second intermediate current value, the third intermediate current value, and the fourth intermediate current value.

[0097] Specifically, the corresponding calculation results can be obtained according to each intermediate current value based on the following formula:

[0098]

[0099] Among them I α1 is the first intermediate current value, I α2 is the second intermediate current value, I β1 is the third intermediate current value, I β2 is the fourth intermediate current value; I lim is the over-current limit threshold.

[0100] in It is represented as the first calculation result; is the second calculation result; is the third calculation result.

[0101] Furthermore, the calculation method of each intermediate current value is:

[0102]

[0103] in is the positive sequence active current component command value; is the negative sequence active current component command value; is the positive sequence reactive current component command value; is the negative-sequence reactive current component command value; γ is the PCC positive- and negative-sequence voltage phase difference, which can be measured by the phase-locked loop of the station controller of the wind-solar station.

[0104] Based on the calculation results obtained above, it can be determined whether the command values ​​of each current component meet the overcurrent limit threshold. The specific steps include:

[0105] When it is determined that at least one of the first calculation result, the second calculation result and the third calculation result does not meet the corresponding overcurrent limit threshold, that is, at least one calculation result is greater than the corresponding The determination result is determined to be the first determination result, that is, it is determined that the current component command value does not meet the overcurrent limit threshold;

[0106] When it is determined that the first calculation result, the second calculation result and the third calculation result all meet their corresponding over-current limit thresholds, that is, the first calculation result, the second calculation result and the third calculation result are all less than or equal to the corresponding The determination result is determined to be the second determination result, that is, it is determined that the current component command value meets the overcurrent limit threshold.

[0107] Further, in the above step S3, if the device determines that the judgment result is the first judgment result that the current command does not meet the overcurrent limit, it is necessary to perform compensation calculations on the positive-sequence reactive current component command value and the negative-sequence reactive current component command value respectively to obtain the positive-sequence reactive current component command update value and the negative-sequence reactive current component command update value.

[0108] Specifically, the specific steps of performing compensation calculation on the positive sequence reactive current component command value in the present application include:

[0109] Respectively obtain the equivalent positive sequence voltage and the corresponding equivalent impedance imaginary part of the power grid on the opposite side of the common connection point, and obtain the preset first control strategy setting instruction value and compensation adjustment parameter;

[0110] Based on the equivalent positive sequence voltage of the grid on the opposite side of the common connection point, the corresponding equivalent impedance imaginary part, the first control strategy setting command value and the compensation adjustment parameter, the first step length is calculated:

[0111]

[0112] Where m + is the first step length corresponding to the positive sequence reactive current component command value; Set the command value for the first control strategy, which can be 0.9pu; X g is the imaginary part of equivalent impedance; is the equivalent positive sequence voltage of the power grid on the opposite side of the common connection point; C is the preset step adjustment parameter, which can be selected as 50.

[0113] Then calculate the difference between the positive sequence reactive current component command value and the corresponding first step length, that is, the current positive sequence reactive current component command value and m + Subtract the difference and use it as the positive sequence reactive current component command update value.

[0114] More specifically, the specific steps of calculating the compensation for the negative-sequence reactive current component command value in the present application include:

[0115] Respectively obtain the equivalent negative sequence voltage and the corresponding equivalent impedance imaginary part of the power grid on the opposite side of the common connection point, and obtain the preset second control strategy setting instruction value and compensation adjustment parameter;

[0116] Based on the equivalent negative sequence voltage of the grid on the opposite side of the common connection point, the corresponding equivalent impedance imaginary part, the second control strategy setting command value and the compensation adjustment parameter, the second step length is calculated:

[0117]

[0118] Where m - is the second step length corresponding to the negative sequence reactive current component command value; Set the command value for the second control strategy, which can be 0.05pu; X g is the imaginary part of equivalent impedance; is the equivalent negative sequence voltage of the power grid on the opposite side of the common connection point; C is the preset step adjustment parameter, which can be selected as 50.

[0119] Then calculate the difference between the negative sequence reactive current component command value and the corresponding second step length, that is, the difference between the negative sequence reactive current component command value and m - Subtract the difference and use it as the negative sequence reactive current component command update value.

[0120] It should be noted that in step S4, each time the device obtains a pair of positive-sequence reactive current component command update values ​​and negative-sequence reactive current component command update values, it will perform a determination to determine whether the current command meets the overcurrent limit threshold, that is, the updated positive-sequence and negative-sequence reactive current component command values ​​are re-combined with the corresponding Make a judgment until the inequality of step S2 is satisfied, such as Figure 4 shown.

[0121] When it is determined that the determination result is the second determination result that the current command satisfies the overcurrent limit, power decoupling inverse transformation is performed on each updated current component command value, and each current component command value after power decoupling inverse transformation is input into the current control loop, and the specific steps are:

[0122] Substitute the calculated current control command value into the power decoupling inverse transformation to obtain as well as Then it is input into the current control loop of the converter. Its power decoupling inverse transformation can be expressed as:

[0123]

[0124] in It is the positive sequence DC current component of the d-axis in the dq coordinate system obtained by the power decoupling inverse transformation; It is the positive sequence DC current component of the q axis in the dq coordinate system obtained by the power decoupling inverse transformation; It is the negative sequence DC current component of the d-axis in the dq coordinate system obtained by the power decoupling inverse transformation; is the negative sequence DC current component of the q axis in the dq coordinate system obtained by the power decoupling inverse transformation; K dp / PQ is the inverse transformation matrix coefficient; is the positive sequence active current component command value; is the negative sequence active current component command value; is the positive sequence reactive current component command value; is the negative sequence reactive current component command value; is the negative sequence DC voltage component of the q axis in the dq coordinate system; is the negative sequence DC voltage component of the d-axis in the dq coordinate system; It is the phase of the negative sequence voltage component measured at the grid connection point.

[0125] Furthermore, in order to further illustrate the performance of the method, the embodiments of the present application are described in detail in combination with specific embodiments. Referring to a photovoltaic power station case, its specific system parameters are shown in Tables 1 and 2. The fault occurred on the grid side at 0s and lasted for 150ms. This application uses the low voltage ride-through control standards of wind and solar power stations as a comparison to illustrate the advantages of the control strategy provided by this application.

[0126] Table 1

[0127]

[0128] Table 2

[0129]

[0130] The comparison results between the control method proposed in this application and the current crossing control standard are as follows: Figure 5-7 As shown. Combined Figure 5 The high and low voltage waveforms of the main transformer at the wind and solar power station grid connection point under the two methods given show that the existing method can only raise the grid connection point phase voltage to a maximum of 0.71pu, while the method proposed in this application can raise it to a maximum of 1.08pu, which is a 52% performance improvement. Figure 6 From the positive and negative sequence voltage diagrams of the wind and solar power station grid connection point under the two methods given, it can be seen that the existing method can only raise the positive sequence voltage of the grid connection point by 0.056pu, while the method proposed in this application can raise it by 0.18pu, and the performance is improved by 221%. The maximum phase voltage amplitude of the system using the existing method is about 0.7pu, and the positive sequence voltage is only raised by 0.056pu, which cannot flexibly adjust the output power of the wind and solar power station. The method proposed in this application raises the positive sequence voltage by 0.18pu and suppresses the negative sequence voltage by 0.11pu. Figure 7 It can be seen that the output currents of the two methods are similar and both meet safety limits. The method proposed in this application achieves a stronger voltage raising capability under similar output current conditions. The maximum phase current amplitude of the control strategy of this application is 1.19pu, which meets the maximum overcurrent tolerance requirements of the wind-solar converter. In contrast, the control method proposed in this application greatly improves the control flexibility of the wind-solar station during faults.

[0131] Furthermore, the wind and solar power station fault power control method provided by the embodiment of the present invention overcomes the defect of the lack of flexibility in reactive control of existing wind and solar power stations, and further proposes a wind and solar power station fault reactive power flexibility control strategy. At present, wind and solar power stations have a lot of reactive power generation capacity during faults, but the fault ride-through control strategy of the existing ride-through control standard is conservative and cannot fully increase the reactive power to support the system voltage. For weak power grid scenarios, it may cause a chain reaction of grid disconnection. The wind and solar power station fault power control method of the present application can give full play to the reactive power generation resources of the wind and solar power station during the fault, and adaptively adjust the reactive output of the wind and solar power station according to the voltage drop program and the system short-circuit ratio. In addition, the control strategy can also ensure that the wind and solar power station outputs a certain amount of active power during the fault, thereby playing a certain supporting role in the frequency stability of the system, and has higher control flexibility than the current standard control strategy.

[0132] Combination Figure 8 As shown, the present application also discloses a wind-solar station fault power control device, the device comprising:

[0133] A parameter acquisition module, used to obtain the current component command value of the wind and solar power station and the positive and negative sequence voltage phase difference of the common connection point; wherein the current component command value includes the positive sequence reactive current component command value and the negative sequence reactive current component command value corresponding to the reactive current, and the positive sequence active current component command value and the negative sequence active current component command value corresponding to the active current;

[0134] A parameter calculation module is used to calculate and determine whether each current component command value meets the overcurrent limit threshold based on the current component command value of the wind and solar power station, the positive and negative sequence voltage phase difference of the common connection point and the overcurrent limit threshold;

[0135] A first determination module is used for, when it is determined that the current component command value does not meet the overcurrent limit threshold, respectively performing compensation calculation on the positive-sequence reactive current component command value and the negative-sequence reactive current component command value to obtain a positive-sequence reactive current component command update value and a negative-sequence reactive current component command update value;

[0136] A parameter updating module, used for judging again whether the positive-sequence reactive current component instruction update value and the negative-sequence reactive current component instruction update value meet the overcurrent limit threshold value respectively, until it is determined that the corresponding current component instruction update value meets the overcurrent limit threshold value;

[0137] A second determination module is used to perform a power decoupling inverse transformation on the current component command value to obtain a transformed current component command value when it is determined that the current component command value meets the overcurrent limit threshold;

[0138] The control execution module is used to input the transformed current component command value into the current control loop to realize the power control of the wind and solar power station.

[0139] The device provided in the embodiment of the present application can achieve Figure 1 To avoid repetition, the various processes implemented by the method embodiment will not be described again here.

[0140] like Fig. 9 As shown, the embodiment of the present application also provides an electronic device, including a processor 701, a memory 702 and a bus 703, wherein the processor 701 and the memory 702 communicate with each other through the bus 703; and a program or instruction stored in the memory 702 and executable on the processor 701, which is executed by the processor 701 to implement the following Figure 1 The various processes of the method embodiment shown in the figure can achieve the same technical effect. To avoid repetition, they will not be described again here.

[0141] The embodiment of the present application also provides a readable storage medium on which a program or instruction is stored. When the program or instruction is executed by a processor, the above Figure 1The various processes of the method embodiments described above can achieve the same technical effect, and will not be described again here to avoid repetition.

[0142] The present application also provides a computer program product, including computer instructions, which, when executed by a processor, implement the above Figure 1 The various processes of the method embodiments described above can achieve the same technical effect, and will not be described again here to avoid repetition.

[0143] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in various embodiments of the present application, the size of the sequence number of the above-mentioned processes does not mean the order of execution, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application. The above-mentioned sequence numbers of the embodiments of the present application are only for description and do not represent the advantages and disadvantages of the embodiments.

[0144] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0145] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another device, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0146] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units; they may be located in one place or distributed on multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0147] In addition, all functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may be a separate unit, or two or more units may be integrated into one unit; the above-mentioned integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0148] A person skilled in the art can understand that all or part of the steps of implementing the above method embodiment can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above method embodiment; and the aforementioned storage medium includes: mobile storage devices, read-only memories (ROM), magnetic disks or optical disks, etc., various media that can store program codes.

[0149] Alternatively, if the above-mentioned integrated unit of the present application is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application can essentially or in other words, the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a device (which can be a terminal or a platform, etc.) to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROMs, magnetic disks, or optical disks.

[0150] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for controlling power failure of a wind and solar power station, characterized in that: The steps include: Obtain the current component command value of the wind and solar power station and the positive and negative sequence voltage phase difference of the common connection point; The current component command values ​​include a positive-sequence reactive current component command value and a negative-sequence reactive current component command value corresponding to the reactive current, and a positive-sequence active current component command value and a negative-sequence active current component command value corresponding to the active current; Based on the current component command value of the wind and solar power station, the positive and negative sequence voltage phase difference of the common connection point and the overcurrent limit threshold, it is calculated and judged whether each current component command value meets the overcurrent limit threshold; When it is determined that the current component command value does not meet the overcurrent limit threshold, compensation calculations are performed on the positive-sequence reactive current component command value and the negative-sequence reactive current component command value to obtain a positive-sequence reactive current component command update value and a negative-sequence reactive current component command update value; Determine again whether the positive-sequence reactive current component instruction update value and the negative-sequence reactive current component instruction update value meet the overcurrent limit threshold value respectively, until it is determined that the corresponding current component instruction update value meets the overcurrent limit threshold value; When it is determined that the current component command value meets the overcurrent limit threshold, a power decoupling inverse transformation is performed on the current component command value to obtain a transformed current component command value; The transformed current component command value is input into the current control loop to realize wind and solar power station power control.

2. The method for controlling power of wind and solar power plant faults according to claim 1, characterized in that: The step of obtaining the command values ​​of each current component of the wind and solar power station comprises: Obtaining an equivalent positive sequence voltage and an equivalent imaginary impedance of the power grid on the opposite side of the common connection point, and obtaining a preset first control strategy setting instruction value; The corresponding positive-sequence reactive current component command value is calculated based on the equivalent positive-sequence voltage of the power grid on the opposite side of the common connection point, the equivalent imaginary part of the impedance, and the first control strategy setting command value.

3. The method for controlling power of wind and solar power plant faults according to claim 2, characterized in that: The step of obtaining the command values ​​of each current component of the wind and solar power station comprises: Obtaining an equivalent negative sequence voltage and an equivalent imaginary impedance of the power grid on the opposite side of the common connection point, and obtaining a preset second control strategy setting instruction value; The corresponding negative-sequence reactive current component command value is calculated based on the equivalent negative-sequence voltage of the power grid on the opposite side of the common connection point, the equivalent imaginary part of the impedance, and the second control strategy setting command value.

4. The method for controlling power of wind and solar power plant faults according to claim 3 is characterized in that: The step of obtaining the command values ​​of each current component of the wind and solar power station comprises: Obtain the positive sequence active current component command value output before the fault; The positive-sequence active current component command value output before the fault is used as the current positive-sequence active current component command value; Set the current negative-sequence active current component command value to zero.

5. The method for controlling power of wind-solar station fault according to claim 1, characterized in that: The step of calculating based on the current component command value of the wind and solar power station, the positive and negative sequence voltage phase difference of the common connection point and the overcurrent limit threshold value includes: Obtaining a first intermediate current value by calculation according to the positive-sequence active current component command value, the negative-sequence reactive current component command value and the positive- and negative-sequence voltage phase difference of the common connection point; A second intermediate current value is obtained by calculating the positive-sequence reactive current component command value, the negative-sequence reactive current component command value and the positive- and negative-sequence voltage phase difference of the common connection point; Obtaining a third intermediate current value by calculation according to the positive-sequence reactive current component command value, the negative-sequence reactive current component command value and the positive- and negative-sequence voltage phase difference of the common connection point; A fourth intermediate current value is obtained by calculation based on the positive-sequence active current component command value, the negative-sequence reactive current component command value and the positive- and negative-sequence voltage phase difference of the common connection point.

6. The method for controlling power of wind and solar power plant faults according to claim 5, characterized in that: The step of calculating based on the current component command value of the wind and solar power station, the positive and negative sequence voltage phase difference of the common connection point and the overcurrent limit threshold value includes: Calculating and obtaining a first calculation result according to the first intermediate current value and the second intermediate current value; Obtaining a second calculation result by calculation according to the first intermediate current value, the second intermediate current value, the third intermediate current value, and the fourth intermediate current value; A third calculation result is obtained by calculation according to the first intermediate current value, the second intermediate current value, the third intermediate current value, and the fourth intermediate current value.

7. The method for controlling power of wind-solar station faults according to claim 6, characterized in that: The step of judging whether each current component command value meets the overcurrent limit threshold comprises: When it is determined that at least one of the first calculation result, the second calculation result and the third calculation result is greater than the overcurrent limit threshold corresponding to itself, the determination result is determined to be the first determination result, that is, it is determined that the current component command value does not meet the overcurrent limit threshold; When it is determined that the first calculation result, the second calculation result and the third calculation result are all less than or equal to their corresponding overcurrent limiting thresholds, the determination result is determined to be the second determination result, that is, it is determined that the current component command value meets the overcurrent limiting threshold.

8. The method for controlling power of wind-solar station faults according to claim 1, characterized in that: The step of performing compensation calculation on the positive sequence reactive current component command value comprises: Respectively obtain the equivalent positive sequence voltage and the corresponding equivalent impedance imaginary part of the power grid on the opposite side of the common connection point, and obtain the preset first control strategy setting instruction value and compensation adjustment parameter; The first step length is calculated based on the equivalent positive sequence voltage of the power grid on the opposite side of the common connection point, the corresponding equivalent impedance imaginary part, the first control strategy setting command value and the compensation adjustment parameter; Calculate the difference between the positive-sequence reactive current component command value and the corresponding first step length, and use the difference result as the positive-sequence reactive current component command update value.

9. The method for controlling power of wind-solar station faults according to claim 1, characterized in that: The step of performing compensation calculation on the negative sequence reactive current component command value comprises: Respectively obtain the equivalent negative sequence voltage and the corresponding equivalent impedance imaginary part of the power grid on the opposite side of the common connection point, and obtain the preset second control strategy setting instruction value and compensation adjustment parameter; The second step length is obtained by calculation based on the equivalent negative sequence voltage of the power grid on the opposite side of the common connection point, the corresponding equivalent impedance imaginary part, the second control strategy setting command value and the compensation adjustment parameter; The difference between the negative-sequence reactive current component command value and the corresponding second step length is calculated, and the difference result is used as the negative-sequence reactive current component command update value.

10. A wind and solar power station fault power control device, characterized in that: The device comprises: A parameter acquisition module, used to obtain the current component command value of the wind and solar power station and the positive and negative sequence voltage phase difference of the common connection point; wherein the current component command value includes the positive sequence reactive current component command value and the negative sequence reactive current component command value corresponding to the reactive current, and the positive sequence active current component command value and the negative sequence active current component command value corresponding to the active current; A parameter calculation module is used to calculate and determine whether each current component command value meets the overcurrent limit threshold based on the current component command value of the wind and solar power station, the positive and negative sequence voltage phase difference of the common connection point and the overcurrent limit threshold; A first determination module is used for, when it is determined that the current component command value does not meet the overcurrent limit threshold, respectively performing compensation calculations on the positive-sequence reactive current component command value and the negative-sequence reactive current component command value to obtain a positive-sequence reactive current component command update value and a negative-sequence reactive current component command update value; A parameter updating module, used for judging again whether the positive-sequence reactive current component instruction update value and the negative-sequence reactive current component instruction update value meet the overcurrent limit threshold value respectively, until it is determined that the corresponding current component instruction update value meets the overcurrent limit threshold value; A second determination module is used to perform a power decoupling inverse transformation on the current component command value to obtain a transformed current component command value when it is determined that the current component command value meets the overcurrent limit threshold; The control execution module is used to input the transformed current component command value into the current control loop to realize the power control of the wind and solar power station.

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