A method and device for controlling power failure of a wind and solar power station

Abstract

The present application relates to a method and device for controlling power during a wind-solar station fault, which includes obtaining the current component command value of the wind-solar station and the positive-negative sequence voltage phase difference of the common connection point; calculating based on the current component command value, the positive-negative sequence voltage phase difference and the overcurrent limit threshold and judging whether each current component command value meets the overcurrent limit threshold; when the current component command value does not meet the overcurrent limit threshold, respectively compensating and calculating the reactive current component command value, obtaining the reactive current component command update value and judging again whether it meets the overcurrent limit threshold; when the current component command value meets the overcurrent limit threshold, performing power decoupling inverse transformation on the current component command value and inputting the result into the current control loop to realize power control of the wind-solar station. This method adaptively adjusts the reactive output of the wind-solar station and provides active power during a fault, plays a supporting role in the frequency stability of the system, and greatly improves the control flexibility of the wind-solar station during a fault.

Description

Technical Field

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

[0002] With the increasing proportion of installed capacity of renewable energy sources such as wind power and photovoltaics, and the inherent weak overcurrent characteristics of renewable energy power electronic equipment, the use of large-scale wind and solar power generation systems connected to weak grids is gradually emerging. Furthermore, with the full-scale construction of large-scale wind and solar power generation bases, the number of such accesses will continue to increase in the future.

[0003] However, large-scale wind and solar power generation is facing increasing challenges in system stability and regulation. Wind and solar power plants are prone to frequent subsynchronous oscillations in weak grid conditions, leading to power outages and other incidents. This results in current wind and solar power systems suffering from a narrow frequency band regulation range, insufficient frequency and voltage support, and insufficient regulation speed, resulting in a lack of control flexibility. Summary of the Invention

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

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

[0006] Obtaining current component command values ​​of the wind and solar power stations and the positive- and negative-sequence voltage phase difference of the common connection point; wherein 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;

[0007] 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 judge 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] 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 respectively, until determining 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, the current component command value is subjected to power decoupling inverse transformation 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 instruction value is calculated based on the equivalent positive-sequence voltage, the equivalent imaginary impedance part and the first control strategy setting instruction value of the power grid on the opposite side of the common connection point.

[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 instruction value is calculated based on the equivalent negative-sequence voltage, the equivalent imaginary impedance part and the second control strategy setting instruction value of the power grid on the opposite side of the common connection point.

[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] Optional: 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 includes:

[0023] Obtaining a first intermediate current value 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 at the common connection point;

[0024] Obtaining a second intermediate current value by calculation based on 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 based on 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 at 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 at the common connection point.

[0027] Optional: 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 includes:

[0028] Calculating 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 determining whether each current component command value meets the overcurrent limit threshold includes:

[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 its corresponding overcurrent limit threshold, 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 limit 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 limit threshold.

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

[0035] Obtaining respectively the equivalent positive sequence voltage and the corresponding 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 and compensation adjustment parameters;

[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 imaginary part of the impedance, the first control strategy setting instruction 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 includes:

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

[0040] The second step length is calculated based on the equivalent negative sequence voltage of the power grid on the opposite side of the common connection point, the corresponding equivalent imaginary part of the impedance, the second control strategy setting instruction 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 is 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, configured to, when determining that the current component command value does not meet the overcurrent limit threshold, respectively perform 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, configured to re-determine whether the positive-sequence reactive current component instruction update value and the negative-sequence reactive current component instruction update value respectively meet the overcurrent limit threshold, until it is determined that the corresponding current component instruction update value meets the overcurrent limit threshold;

[0047] a second determination module, configured to perform a power decoupling inverse transformation on the current component command value to obtain a transformed current component command value when determining 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 wind and solar power station power control.

[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 amount of 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 This is a flow chart of the method for controlling power failure in a wind-solar station in an embodiment of the present application.

[0053] Figure 2 This is a schematic diagram of the grid-connected topology 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 This 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 showing the comparison of the high and low voltage side voltages of the main transformer at the 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 Figure 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 at the grid connection point of the control method in the embodiment of the present application with the current ride-through control standard. Figure 6 a is a schematic diagram of the positive and negative sequence voltages at the grid connection point of the station under the control method of this embodiment; Figure 6 Figure b in the middle 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 waveforms output by the station according to the control method in the embodiment of the present application and 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 of this embodiment; Figure 7 Figure b is a schematic diagram of the three-phase current waveform output by the station under the current ride-through control standard.

[0059] Figure 8 This is a structural diagram of the wind-solar station fault power control device in an embodiment of the present application.

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

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

[0062] Combine Figure 1 As shown, the embodiment of the present application specifically discloses a method for controlling power failure of a wind-solar station, which includes 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 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;

[0064] Step S2: Calculating based on the current component command values ​​of the wind and solar power stations, the positive and negative sequence voltage phase difference of the common connection point and the overcurrent limit threshold, and determining 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, 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, performing a power decoupling inverse transformation on the current component command value to obtain a transformed current component command value;

[0068] Step S6: Input the transformed current component command value into the current control loop to achieve 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 that executes 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 into dq coordinate system α 、v β 、i α 、i β Converted 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 instruction value is calculated based on the equivalent positive-sequence voltage, the equivalent imaginary impedance part and the first control strategy setting instruction value of the power grid on the opposite side of the common connection point.

[0076] Furthermore, the step of obtaining the command values ​​of the current components of the wind and solar power stations 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 instruction value is calculated based on the equivalent negative-sequence voltage, the equivalent imaginary impedance part and the second control strategy setting instruction value of the power grid on the opposite side of the common connection point.

[0079] Based on the above steps, the positive sequence reactive current component command values ​​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 the equivalent impedance; is the equivalent positive sequence voltage of the power grid on the opposite side of the common connection point; 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 instruction 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 instruction 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, wherein the calculation steps include:

[0089] Obtaining a first intermediate current value 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 at the common connection point;

[0090] Obtaining a second intermediate current value by calculation based on 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 based on 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 at 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 at the common connection point.

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

[0094] Calculating 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 overcurrent limit threshold.

[0100] in It is expressed 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 phase difference between the positive and negative sequence voltages of the PCC, which can be measured by the phase-locked loop of the station controller of the wind and solar power station.

[0104] Based on the calculation results obtained above, it is possible to determine 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, there is at least one calculation result 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 overcurrent 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] Furthermore, in the above step S3, if the device determines that the judgment result is the first judgment result that the current instruction does not meet the overcurrent limit, it is necessary to perform compensation calculations on the positive-sequence reactive current component instruction value and the negative-sequence reactive current component instruction value respectively to obtain the positive-sequence reactive current component instruction update value and the negative-sequence reactive current component instruction update value.

[0108] Specifically, the specific steps of calculating the compensation for the positive sequence reactive current component command value in this application include:

[0109] Obtaining respectively the equivalent positive sequence voltage and the corresponding 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 and compensation adjustment parameters;

[0110] Based on the equivalent positive sequence voltage of the grid on the opposite side of the common connection point, the corresponding equivalent imaginary impedance, the command value set by the first control strategy, and the compensation adjustment parameters, 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 the 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 instruction 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] Obtaining the equivalent negative sequence voltage and the corresponding equivalent imaginary impedance of the power grid on the opposite side of the common connection point respectively, and obtaining 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 imaginary impedance, the second control strategy setting command value and the compensation adjustment parameter, the second step length is calculated as follows:

[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 the 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, 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 instruction update value.

[0120] It should be noted that in step S4, each time the device obtains a pair of positive sequence reactive current component instruction update value and negative sequence reactive current component instruction update value, it will perform a determination to determine whether the current instruction meets the overcurrent limit threshold, that is, the updated positive and negative sequence reactive current component instruction values ​​are re-compared with the corresponding Make judgments 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. The specific steps are as follows:

[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 is the positive sequence DC current component of the d-axis in the dq coordinate system obtained by the power decoupling inverse transformation; is the positive sequence DC current component of the q axis in the dq coordinate system obtained by the power decoupling inverse transformation; 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; is the phase of the negative sequence voltage component measured at the grid connection point.

[0125] Furthermore, to further illustrate the performance of this method, the embodiments of this application are described in detail in conjunction 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 side voltage waveforms of the main transformer at the wind and solar station grid connection point under the two methods given show that the existing method can only raise the phase voltage at the grid connection point 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 regulate 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. From Figure 7 It can be seen that the output currents of the two methods are similar and both meet safety limits. However, the method proposed in this application achieves a stronger voltage boost capability under similar output current conditions. The maximum phase current amplitude of the control strategy in this application is 1.19 pu, which meets the maximum overcurrent tolerance requirements of the wind-solar converter. In contrast, the control method proposed in this application significantly 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] Combine 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 is 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, configured to, when determining that the current component command value does not meet the overcurrent limit threshold, respectively perform 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, configured to re-determine whether the positive-sequence reactive current component instruction update value and the negative-sequence reactive current component instruction update value respectively meet the overcurrent limit threshold, until it is determined that the corresponding current component instruction update value meets the overcurrent limit threshold;

[0137] a second determination module, configured to perform a power decoupling inverse transformation on the current component command value to obtain a transformed current component command value when determining 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 wind and solar power station power control.

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

[0140] like Figure 9 As shown, the embodiment of the present application further 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 here.

[0141] The embodiment of the present application also provides a readable storage medium on which a program or instruction is stored, and when the program or instruction is executed by the processor, the above Figure 1The various processes of the method embodiments described above can achieve the same technical effects, 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 effects, 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 the 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 the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. 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 serial numbers of the embodiments of the present application are for description only and do not represent the advantages and disadvantages of the embodiments.

[0144] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0145] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, 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 across multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the scheme of this embodiment.

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

[0148] Those skilled in the art will understand that all or part of the steps of implementing the above-mentioned 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-mentioned method embodiment; and the aforementioned storage medium includes: mobile storage devices, read-only memories (ROM), magnetic disks or optical disks, and other 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 is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for enabling a device (which can be a terminal or 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 embodiment 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 in 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; 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 judge 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 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; The steps of calculating the compensation for the positive sequence reactive current component command value include: Obtaining respectively the equivalent positive sequence voltage and the corresponding 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 and compensation adjustment parameters; 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 imaginary part of the impedance, the first control strategy setting instruction 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; The steps of calculating the compensation for the negative sequence reactive current component command value include: Obtaining the equivalent negative sequence voltage and the corresponding equivalent imaginary impedance of the power grid on the opposite side of the common connection point respectively, and obtaining the preset second control strategy setting instruction value and compensation adjustment parameter; The second step length is calculated based on the equivalent negative sequence voltage of the power grid on the opposite side of the common connection point, the corresponding equivalent imaginary part of the impedance, the second control strategy setting instruction value and the compensation adjustment parameter; Calculate the difference between the negative-sequence reactive current component command value and the corresponding second step length, and use the difference result as the negative-sequence reactive current component command update value; 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 respectively, until determining 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, the current component command value is subjected to power decoupling inverse transformation 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 during wind and solar power station faults according to claim 1, wherein: The step of obtaining the command values ​​of each current component of the wind and solar power station includes: 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 instruction value is calculated based on the equivalent positive-sequence voltage, the equivalent imaginary impedance part and the first control strategy setting instruction value of the power grid on the opposite side of the common connection point.

3. The method for controlling power during wind and solar power station faults according to claim 2, wherein: The step of obtaining the command values ​​of each current component of the wind and solar power station includes: Obtaining the equivalent negative sequence voltage and the 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 instruction value is calculated based on the equivalent negative-sequence voltage, the equivalent imaginary impedance part and the second control strategy setting instruction value of the power grid on the opposite side of the common connection point.

4. The method for controlling power during wind and solar power station faults according to claim 3, wherein: The step of obtaining the command values ​​of each current component of the wind and solar power station includes: 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 during wind and solar power station faults according to claim 1, wherein: 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: Obtaining a first intermediate current value 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 at the common connection point; Obtaining a second intermediate current value by calculation based on 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 at the common connection point; Obtaining a third intermediate current value by calculation based on 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 at 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 at the common connection point.

6. The method for controlling power during wind and solar power station 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 comprises: Calculating 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 during wind and solar power station faults according to claim 6, characterized in that: The step of determining 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 its corresponding overcurrent limit threshold, 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 limit 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 limit threshold.

8. A wind-solar station fault power control device, characterized in that: The device comprises: A parameter acquisition module is 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 configured to, when determining that the current component command value does not meet the overcurrent limit threshold, respectively perform 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; The steps of calculating the compensation for the positive sequence reactive current component command value include: Obtaining respectively the equivalent positive sequence voltage and the corresponding 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 and compensation adjustment parameters; 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 imaginary part of the impedance, the first control strategy setting instruction 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; The steps of calculating the compensation for the negative sequence reactive current component command value include: Obtaining the equivalent negative sequence voltage and the corresponding equivalent imaginary impedance of the power grid on the opposite side of the common connection point respectively, and obtaining the preset second control strategy setting instruction value and compensation adjustment parameter; The second step length is calculated based on the equivalent negative sequence voltage of the power grid on the opposite side of the common connection point, the corresponding equivalent imaginary part of the impedance, the second control strategy setting instruction value and the compensation adjustment parameter; Calculate the difference between the negative-sequence reactive current component command value and the corresponding second step length, and use the difference result as the negative-sequence reactive current component command update value; a parameter updating module, configured to re-determine whether the positive-sequence reactive current component instruction update value and the negative-sequence reactive current component instruction update value respectively meet the overcurrent limit threshold, until it is determined that the corresponding current component instruction update value meets the overcurrent limit threshold; a second determination module, configured to perform a power decoupling inverse transformation on the current component command value to obtain a transformed current component command value when determining 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 wind and solar power station power control.

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