A Method for Measuring the Response Time of a Dynamic Reactive Power Compensation Device

Abstract

The present invention discloses a method for measuring the response time of a dynamic reactive power compensation device, including: Step 1, obtaining synchronous sampling signals of the voltage and current of the branch of the dynamic reactive power compensation device and the branch of the compensation object, and calculating the instantaneous reactive power within the sampling period; Step 2, respectively filtering the instantaneous reactive power to remove interfering harmonics; Step 3, eliminating the DC component of the instantaneous reactive power after filtering; Step 4, performing a discrete Fourier transform on the array composed of the instantaneous reactive power after eliminating the DC component to obtain a corresponding frequency-domain array, and calculating the cross-power spectrum of the instantaneous reactive power of the branch of the dynamic reactive power compensation device and the branch of the compensation object through the frequency-domain array; Step 5, performing an inverse discrete Fourier transform on the cross-power spectrum, performing peak detection, and calculating the dynamic response time. This method does not require adding an additional disturbance source, does not affect the normal operation of the equipment, and can better reflect the compensation and response conditions of the dynamic reactive power compensation device in the actual power grid, and is easy to implement on-site.

Description

Technical Field

[0001] The present invention relates to the field of testing dynamic reactive power compensation devices, and particularly to a method for measuring the response time of a dynamic reactive power compensation device. Background Art

[0002] With the large-power impact loads such as AC / DC arc furnaces, electrified railways, and urban rail transit loads, as well as the large-scale grid connection of large-capacity intermittent new energy power generation stations, the application demand for dynamic reactive power compensation devices (Dynamic Var Compensator, hereinafter referred to as DVC) has become prominent. The response time of DVC is an important guarantee for its dynamic compensation performance, which refers to the time from the input of the control signal (reference voltage) until the compensation device first reaches 90% of the target value. In the technical standards of various DVCs, specific technical requirements for its response time will be put forward.

[0003] Currently, there are the following several schemes for testing the response time of dynamic reactive power compensation devices:

[0004] (1) Reference [1] (Fan Gaofeng, Pei Zheyi, Xiao Yang, etc. Research on the Response Speed and Detection Method of Dynamic Reactive Power Compensation Devices in Wind Farms [J]. Smart Grid, 2015(2):6) discloses a method for the response speed and detection of dynamic reactive power compensation devices in wind farms. Specifically, it approximately calculates whether the system response time meets the requirements by testing the sum of the disturbance detection time and the system response time. The specific method is as follows: Switch on and off a certain capacity of capacitors (or fan collector lines) in the wind farm, and measure the time elapsed from the occurrence of the disturbance in the power grid until the controlled quantity first reaches 90% of the target value, that is, the sum of the disturbance detection time and the system response time, and then deduce the system response time.

[0005] (2) Reference [2] (Zhang Jinping, Yan Qing, Fan Yi, Wang Ruiming, Chang Xiqiang, Guo Xiaolong, Zhang Yanjun. A Method for Detecting the Dynamic Response Time of Reactive Power Compensation Devices in Wind Farms [P]. Beijing: CN105388372A, 2016-03-09) discloses a method for detecting the dynamic response time of reactive power compensation devices in wind farms. The method includes: (1) Analyze the requirements for the dynamic response time of reactive power compensation devices in wind farms in relevant standards; (2) Determine the time when the background unit of the test device sends a synchronization signal to the data acquisition system, the time when it sends the voltage / reactive power target value to the reactive power compensation device, and the time when the reactive power compensation device outputs a feedback signal to the data acquisition system; (3) Obtain the dynamic response time of the reactive power compensation device; (4) Send each synchronization signal and feedback signal to the data acquisition system, and call the data acquisition system to obtain the accurate dynamic response time of the reactive power compensation device; (5) Verify whether the accurate dynamic response time meets the standard requirements.

[0006] (3)References [3] (Wu Yanan, Mao Huafeng, Shen Xianshun, Li Jun, Lu Jing, Mao Zhiwei. Evaluation Method for Dynamic Response Time of Thyristor-Controlled Reactor Based on Trigger Detection [J]. High Power Laser and Particle Beams, 2019, 31(05): 72-76) and Reference [4] (Wu Yanan, Fu Peng, Li Jun, Mao Huafeng, Xu Liuwei, Tao Jun, Lu Jing. Test Method for Dynamic Response Performance of TCR-Type SVC for Large-Capacity Impact Loads [P]. Anhui Province: CN106291170B, 2020-09-29) disclose an evaluation method for the dynamic response time of TCR based on actual trigger pulse detection. First, a step reactive power reference quantity is generated by cutting off the FC branch at the zero crossing of the circuit breaker to unify the reference time, and at the same time, the TCR phase current waveform is collected to obtain the actual trigger angle, which is compared with the lower limit value of the trigger angle, so as to accurately evaluate the dynamic response time characteristics of TCR.

[0007] (4)Reference [5] (Zhang Jinping, Yu Xiuyue, Fan Yi, Li Qing. A Test System for the Dynamic Response Time of a Reactive Power Compensation Device Considering Communication Delay [P]. Beijing: CN205594088U, 2016-09-21) discloses a test system for the dynamic response time of a reactive power compensation device considering communication delay. The specific steps include: (1) Using the computer upper computer to send a control instruction to the intelligent instruction sending device. After receiving the control instruction, the intelligent instruction sending device sends a control instruction to the reactive power compensation device and outputs a synchronization signal to the data acquisition system at the same time. After receiving this signal, the data acquisition system automatically starts the waveform recording function of the acquisition device; (2) After receiving the instruction signal from the intelligent instruction sending device, the reactive power compensation device outputs a feedback signal to the data acquisition system, which is the T1 period; (3) After receiving the control instruction, the reactive power compensation device performs calculation and processing until it starts to output reactive current, which is the T2 period; (4) Starting from the moment when the reactive power compensation device starts to output reactive current, until the reactive current output by the reactive power compensation device reaches 90% of the target value, which is the system adjustment time of the reactive power compensation device, that is, the T3 period.

[0008] However, the inventors found that: in the existing DVC response time detection methods, a large reactive voltage step is mainly generated by a disturbance source under test conditions, and then the response time measurement is achieved based on the effective values or instantaneous reactive power curves of the grid voltage, current, and reactive power during the step process. However, in actual application scenarios, testing under test conditions will not only affect the normal operation of the equipment, but also require a disturbance source that can generate step disturbances, with relatively strict requirements for test conditions, which is not conducive to on-site implementation. Moreover, in actual application scenarios, factors such as communication delay between devices, control parameter adjustment, and changes in reactive power compensation requirements will all affect the response time of the DVC. There are significant differences in the response time test results under different application scenarios, and they cannot reflect the actual response of the dynamic reactive power compensation device during operation. In addition, some application scenarios often do not have the conditions to generate a large reactive voltage step, and it is difficult to accurately capture the input moment of the control signal, which poses a great challenge to the on-site measurement of the response time.

[0009] Therefore, how to utilize on-site operating conditions to achieve accurate on-line measurement of the DVC response time without affecting the normal operation of the equipment and devices is an urgent problem to be solved. Summary of the Invention

[0010] The present invention provides a method for measuring the response time of a dynamic reactive power compensation device, which can well solve the problems that the existing methods for measuring the response time of a dynamic reactive power compensation device have strict requirements for test conditions and cannot accurately reflect the actual operation of the dynamic reactive power compensation device.

[0011] The technical solution of the present invention is as follows:

[0012] A method for measuring the response time of a dynamic reactive power compensation device includes the following steps:

[0013] Step 1: Obtain sampling signals obtained by synchronously sampling the voltages and currents of the branch of the dynamic reactive power compensation device and the branch of the compensation object, and calculate the instantaneous reactive power of the branch of the dynamic reactive power compensation device and the branch of the compensation object within the sampling period according to the sampling signals;

[0014] Step 2: Filter the instantaneous reactive power of the branch of the dynamic reactive power compensation device obtained in Step 1 and the instantaneous reactive power of the branch of the compensation object respectively to remove interfering harmonics;

[0015] Step 3: Eliminate the DC component of the instantaneous reactive power after filtering in Step 2;

[0016] Step 4: Perform a discrete Fourier transform on the array composed of the instantaneous reactive power after eliminating the DC component in Step 3 to obtain a corresponding frequency-domain array, and calculate the cross-power spectrum of the instantaneous reactive power of the branch of the dynamic reactive power compensation device and the branch of the compensation object through the corresponding frequency-domain array;

[0017] Step 5: Perform an inverse discrete Fourier transform on the cross-power spectrum obtained in Step 3 to obtain an array of generalized cross-correlation coefficients. Detect the peaks of the array of generalized cross-correlation coefficients, determine the delay data points corresponding to the peaks, and calculate the dynamic response time of the dynamic reactive power compensation device based on the determined delay data points.

[0018] The method for measuring the response time of the dynamic reactive power compensation device of the present invention has the following advantages:

[0019] By using the reactive power fluctuations of the compensation object and the reactive power compensation process data of the dynamic reactive power compensation device, and through generalized cross-correlation calculation, accurate measurement of the response time of the dynamic reactive power compensation device can be achieved. There is no need to add additional disturbance sources, which does not affect the normal operation of the equipment, and can better reflect the compensation and response of the dynamic reactive power compensation device in the actual power grid, and is easy to implement on-site. Description of the Drawings

[0020] The following briefly introduces the drawings used in the description of the embodiments. These drawings are only a part of the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 is a flowchart of the method for measuring the response time of the dynamic reactive power compensation device of the present invention;

[0022] Figure 2 is a schematic diagram of the connection of measuring points of the DC arc furnace power distribution system in the response time measurement method of the embodiment of the present invention;

[0023] Figure 3 is a graph of the changing trend of the instantaneous reactive power of the DC arc furnace and the SVC feeder in the response time measurement method of the embodiment of the present invention;

[0024] Figure 4 is a graph of the changing trend of the three-phase instantaneous reactive power of the DC arc furnace and the SVC device feeder in the response time measurement method of the embodiment of the present invention;

[0025] Figure 5 is a graph of the changing trend of the three-phase instantaneous reactive power of the DC arc furnace and the SVC device feeder after removing the DC component in the response time measurement method of the embodiment of the present invention;

[0026] Figure 6 is the power spectrum and cross-power spectrum of the instantaneous reactive power of the DC arc furnace and the SVC device feeder in the response time measurement method of the embodiment of the present invention, where (a) is the power spectrum of the instantaneous reactive power of the DC arc furnace; (b) is the power spectrum of the instantaneous reactive power of the SVC; (c) is the cross-power spectrum of the DC arc furnace and the SVC device;

[0027] Figure 7 It is a curve diagram of the generalized mutual correlation coefficient of the instantaneous reactive power of the DC arc furnace and the SVC device feeder in the response time measurement method of Example 3 of the present invention. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, so that the above-mentioned and other objects, features and advantages of the present invention are clearer. The same reference numerals in all the drawings indicate the same parts. The drawings are not deliberately drawn to scale, and the focus is on illustrating the subject matter of the present invention.

[0029] like Figure 1 As shown, the present invention provides a method for measuring the response time of a dynamic reactive power compensation device, comprising the following steps:

[0030] Step 1, obtaining a sampling signal obtained by synchronously sampling the voltage and current of a dynamic reactive power compensation device branch and a compensation object branch, and calculating the instantaneous reactive power of the dynamic reactive power compensation device branch and the compensation object branch within a sampling period according to the sampling signal;

[0031] Step 2, filtering the instantaneous reactive power of the branch of the dynamic reactive compensation device and the instantaneous reactive power of the compensation object branch obtained in step 1 respectively to remove interfering harmonics;

[0032] Step 3, eliminating the DC component of the instantaneous reactive power after filtering in step 2;

[0033] Step 4, performing discrete Fourier transform on the instantaneous reactive power array with the DC component eliminated in step 3 to obtain a corresponding frequency domain array, and calculating the mutual power spectrum of the instantaneous reactive power of the branch of the dynamic reactive compensation device and the compensation object branch through the corresponding frequency domain array;

[0034] Step 5, performing an inverse discrete Fourier transform on the mutual power spectrum obtained in step 3 to obtain an array of generalized mutual correlation coefficients, performing peak detection on the array of generalized mutual correlation coefficients, determining the delayed data points corresponding to the peak values, and calculating the dynamic response time of the dynamic reactive power compensation device based on the determined delayed data points.

[0035] In step 1 of the above measurement method, the sampled three-phase voltage digital signals of the dynamic reactive power compensation device branch and the compensation object branch are u a (k),u b (k),u c (k) The three-phase current digital signals of the compensation object branch are i a1 (k), i b1 (k), ic1 (k), the three-phase current digital signals of the branch of the dynamic reactive power compensation device are respectively i a2 (k), i b2 (k), i c2 (k); the instantaneous reactive powers of the compensated object branch and the dynamic reactive power compensation device branch are calculated respectively through the following formulas (1) and (2):

[0036]

[0037]

[0038] In the above formulas (1) and (2), q1(k) is the instantaneous reactive power array of the compensated object branch within the sampling period; q2(k) is the instantaneous reactive power array of the dynamic reactive power compensation device branch within the sampling period; u a (k), u b (k), u c (k) are the time-domain discrete sampling data of the three-phase voltages of the power supply bus A, B, and C within the sampling period respectively; i a1 (k), i b1 (k), i c1 (k) are the time-domain discrete sampling data of the three-phase currents of the A, B, and C phases of the compensated object branch respectively; i a2 (k), i b2 (k), i c2 (k) are the time-domain discrete sampling data of the three-phase currents of the A, B, and C phases of the dynamic reactive power compensation device branch respectively; k is the sampling point number, k = 1, 2, 3,..., MN, M is the power frequency cycle number of sampling, and N is the number of sampling points per power frequency cycle.

[0039] In step 1 of the above measurement method, the sampling period covers at least one complete dynamic compensation process of the dynamic reactive power compensation device;

[0040] The value of N is greater than or equal to 16.

[0041] In step 1, multiply the calculated instantaneous reactive power of the dynamic reactive power compensation device branch by -1 as the final instantaneous reactive power of the dynamic reactive power compensation device branch.

[0042] In step 2 of the above measurement method, a 6th-order Butterworth low-pass filter is used to filter the instantaneous reactive power array to remove interfering harmonics. The expression of the transfer function H(z) of the 6th-order Butterworth low-pass filter is:

[0043]

[0044] In the above formula (3), a and b are the coefficients of the transfer function of the 6th-order Butterworth low-pass filter respectively;

[0045] The cut-off frequency of the 6th-order Butterworth low-pass filter matches the interfering harmonics in the instantaneous reactive power to be filtered.

[0046] In step 3 of the above measurement method, the DC component of the filtered instantaneous reactive power array is eliminated by the following formulas (4) and (5):

[0047] q1(k) = q1(k) - mean(q1(k)) (4);

[0048] q2(k) = q2(k) - mean(q2(k)) (5);

[0049] In the above formulas (4) and (5), mean(q1(k)) represents calculating the mean value of the instantaneous reactive power array q1(k) of the branch of the object to be compensated; mean(q2(k)) represents calculating the mean value of the instantaneous reactive power array q2(k) of the branch of the dynamic reactive power compensation device;

[0050] In step 4, the discrete Fourier transform is respectively performed on the instantaneous reactive power arrays of the compensated object branch and the dynamic reactive power compensation device branch after filtering according to the following formulas (6) and (7) to obtain the corresponding frequency-domain arrays Q1(k) and Q2(k), and the formulas (6) and (7) are respectively:

[0051]

[0052]

[0053] Multiply the conjugates of Q1(k) and Q2(k) according to the following formula (8) to obtain the cross-power spectrum The formula (8) is:

[0054]

[0055] In step 5, perform the inverse discrete Fourier transform on the cross-power spectrum to obtain the array of generalized cross-correlation coefficients The formula (9) is:

[0056]

[0057] In step 5, for the obtained array of generalized cross-correlation coefficients perform peak detection to determine the delay data point N corresponding to the peak p , and calculate the dynamic response time T of the dynamic reactive power compensation device according to the following formula (10) s , and the formula (10) is

[0058]

[0059] In the above formula (10), N is the number of points sampled per power frequency cycle; N p is the number of delayed data points; f s is the power grid frequency; T s is the calculated response time of the dynamic compensation device, and the unit of this response time is ms.

[0060] The method of the present invention can perform synchronous measurement under the condition that both the DVC and the compensated object are operating normally. By using the reactive power fluctuation of the compensated object and the reactive power compensation process data of the DVC, through generalized cross-correlation calculation, accurate measurement of the DVC response time can be achieved without adding additional disturbance sources, without affecting the normal operation of the system, and it can better reflect the compensation and response of the DVC in the actual power grid, and is easy to implement on-site.

[0061] The embodiments of the present invention will be further described below in conjunction with the drawings of the present invention. It should be noted that the parts not described in detail below should be understood as well-known in the art.

[0062] Embodiment

[0063] Taking the measurement of the response time of the SVC compensation device in the distribution system of a DC arc furnace as an example, the measurement method of the present invention will be further described.

[0064] The test points for measuring the response time of the SVC compensation device in the distribution system of the DC arc furnace are set as Figure 2 shown.

[0065] Time-domain discrete signals of the voltage of the 35 kV power supply bus of the DC arc furnace, the current of the feeder of the DC arc furnace, and the current of the feeder of the SVC device are obtained. The number of points sampled per power frequency cycle is N = 256, and the period of a single sampling is M = 50 power frequency cycles. Then, the data lengths of the time-domain discrete signals of the current of the feeder of the DC arc furnace, the current of the feeder of the SVC device, and the voltage of the power supply bus are all 12,800 sampling points. The trends of the instantaneous reactive power of the feeder of the DC arc furnace and the SVC device calculated according to formulas (1) and (2) are respectively as Figure 3 shown.

[0066] Filter the instantaneous reactive power. Select a 6th-order Butterworth low-pass filter, and the cut-off frequency of the filter is 70 Hz. The transfer function parameters of the low-pass filter designed according to relevant software are shown in Table 1:

[0067] Table 1 Parameters of the 6th-order Butterworth filter

[0068] Array number 1 2 3 4 5 6 7 Array a 1 -5.86724 14.34498 -18.7072 13.72401 -5.37025 0.875667 Array b 2.41E-11 1.44E-10 3.61E-10 4.82E-10 3.61E-10 1.44E-10 2.41E-11

[0069] The changing trends of the instantaneous reactive power of the filtered DC electric arc furnace and the feeder of the SVC device are as follows Figure 4 as shown

[0070] To reduce the influence of the DC component on the calculation result of the power spectrum, the DC component in the instantaneous reactive power trend data of the DC electric arc furnace and the feeder of the SVC device is eliminated, as shown Figure 5 as shown

[0071] The discrete Fourier transform is performed on the arrays of the instantaneous reactive power of the filtered and DC-removed (i.e., DC component eliminated) DC electric arc furnace and the feeder of the SVC device to calculate the power spectrum of the instantaneous reactive power of the DC electric arc furnace and the feeder of the SVC device. The calculation results of the amplitudes of the power spectrum are as shown Figure 6 (a) and (b). The power spectrum of the SVC device is conjugated and then multiplied by the power spectrum of the DC electric arc furnace to obtain the cross-power spectrum of the instantaneous reactive power of the DC electric arc furnace and the feeder of the SVC device. The calculation results of the amplitudes of the cross-power spectrum are as shown Figure 6 (c).

[0072] The inverse discrete Fourier transform is performed on the cross-power spectrum to obtain the changing trend of the generalized cross-correlation coefficient as shown Figure 7 as shown. For Figure 7 the generalized cross-correlation coefficient curve in, peak detection is performed to determine the delay data point N corresponding to the peak p = 176. Since the number of sampling points per cycle is N = 256, according to formula (10), the dynamic response time T of the SVC device for this measurement is calculated S = 13.75 ms

[0073] The method for measuring the response time of the dynamic reactive power compensation device based on generalized cross-correlation according to the present invention performs synchronous measurement under the condition that both the DVC and the compensation object are operating normally. By using the reactive power fluctuation of the compensation object and the data of the DVC reactive power compensation process, accurate measurement of the DVC response time is achieved through generalized cross-correlation calculation, without adding additional disturbance sources, without affecting the normal operation of the system, and more capable of reflecting the compensation and response of the DVC in the actual power grid, and is easy to implement on site

[0074] The parts not detailed in the above embodiments can be understood as the knowledge known to those skilled in the art. Some or all of the steps involved in the method of the embodiments of the present invention can be the hardware implementation corresponding to the program instructions. The program refers to a set of instructions stored in a readable storage medium that can be executed in a specific order

[0075] Those skilled in the art can understand that the above embodiments are only the preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. For those skilled in the art, any substitutions and changes that can be easily conceived according to the technical scope disclosed by the present invention shall fall within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for measuring the response time of a dynamic reactive power compensation device, characterized in that, It includes the following steps: Step 1: Obtain the sampling signals obtained by synchronously sampling the voltages and currents of the branches of the dynamic reactive power compensation device and the branches of the compensation object, and calculate the instantaneous reactive power of the branches of the dynamic reactive power compensation device and the branches of the compensation object within the sampling period according to the sampling signals; Step 2: Filter the instantaneous reactive power of the branches of the dynamic reactive power compensation device obtained in Step 1 and the instantaneous reactive power of the branches of the compensation object respectively to remove interfering harmonics; Step 3: Eliminate the DC component of the instantaneous reactive power after filtering in Step 2; Step 4: Perform a discrete Fourier transform on the array composed of the instantaneous reactive power after eliminating the DC component in Step 3 to obtain the corresponding frequency-domain array, and calculate the cross-power spectrum of the instantaneous reactive power of the branches of the dynamic reactive power compensation device and the branches of the compensation object through the corresponding frequency-domain array; Step 5: Perform an inverse discrete Fourier transform on the cross-power spectrum obtained in Step 3 to obtain an array of generalized cross-correlation coefficients, perform peak detection on the array of generalized cross-correlation coefficients, determine the delay data point corresponding to the peak, and calculate the dynamic response time of the dynamic reactive power compensation device according to the determined delay data point.

2. The method for measuring the response time of a dynamic reactive power compensation device according to claim 1, characterized in that, In the said step 1, the three-phase voltage digital signals of the branch of the dynamic reactive power compensation device and the branch of the compensation object obtained by synchronous sampling are respectively u a (k), u b (k), u c (k), and the three-phase current digital signals of the branch of the compensation object are respectively i a1 (k), i b1 (k), i c1 (k), and the three-phase current digital signals of the branch of the dynamic reactive power compensation device are respectively i a2 (k), i b2 (k), i c2 (k); the instantaneous reactive powers of the branch of the compensation object and the branch of the dynamic reactive power compensation device are respectively calculated by the following formulas (1) and (2): In the above formulas (1) and (2), q1(k) is the instantaneous reactive power array of the branch of the object to be compensated within the sampling period; q2(k) is the instantaneous reactive power array of the branch of the dynamic reactive power compensation device within the sampling period; u a (k), u b (k), u c (k) are the time-domain discrete sampling data of the three-phase voltages of the power supply bus A, B, and C within the sampling period respectively; i a1 (k), i b1 (k), i c1 (k) are the time-domain discrete sampling data of the three-phase currents of the branch of the object to be compensated for A, B, and C respectively; i a2 (k), i b2 (k), i c2 (k) are the time-domain discrete sampling data of the three-phase currents of the branch of the dynamic reactive power compensation device for A, B, and C respectively; k is the sampling point number, k = 1, 2, 3,..., MN, M is the number of power frequency cycles sampled, and N is the number of sampling points per power frequency cycle.

3. The method for measuring the response time of a dynamic reactive power compensation device according to claim 2, characterized in that, In Step 1, the sampling period covers at least one complete dynamic compensation process of the dynamic reactive power compensation device; The value of N is greater than or equal to 16; In Step 1, multiply the calculated instantaneous reactive power of the branches of the dynamic reactive power compensation device by -1 as the final instantaneous reactive power of the branches of the dynamic reactive power compensation device.

4. The method for measuring the response time of a dynamic reactive power compensation device according to claim 2, characterized in that, In Step 2, use a 6th-order Butterworth low-pass filter to filter the instantaneous reactive power array to remove interfering harmonics. The expression of the transfer function H(z) of the 6th-order Butterworth low-pass filter is: In the above formula (3), a and b are the coefficients of the transfer function of the 6th-order Butterworth low-pass filter respectively; The cut-off frequency of the 6th-order Butterworth low-pass filter matches the interfering harmonics in the instantaneous reactive power to be filtered.

5. The method for measuring the response time of a dynamic reactive power compensation device according to claim 2, characterized in that, In Step 3, eliminate the DC component of the instantaneous reactive power array after filtering through the following formulas (4) and (5), which are: q1(k) = q1(k) - mean(q1(k)) (4); q2(k) = q2(k) - mean(q2(k)) (5); In the above formulas (4) and (5), mean(q1(k)) represents calculating the mean value of the instantaneous reactive power array q1(k) of the branches of the compensation object; mean(q2(k)) represents calculating the mean value of the instantaneous reactive power array q2(k) of the branches of the dynamic reactive power compensation device; In Step 4, perform discrete Fourier transforms on the instantaneous reactive power arrays of the branches of the compensation object and the dynamic reactive power compensation device after filtering according to the following formulas (6) and (7) respectively to obtain the corresponding frequency-domain arrays Q1(k) and Q2(k). The formulas (6) and (7) are respectively: Multiply the conjugate of Q1(k) and Q2(k) according to the following formula (8) to obtain the cross-power spectrum The formula (8) is as follows: In the said step 5, the cross-power spectrum is subjected to the inverse discrete Fourier transform according to formula (10). to obtain an array of generalized cross-correlation coefficients The said formula (9) is as follows: In the said step 5, for the array of the obtained generalized cross-correlation coefficients perform peak detection to determine the delay data point N corresponding to the peak p , and calculate the dynamic response time T of the said dynamic reactive power compensation device according to the following formula (10) s , and the formula (10) is In the above formula (10), N is the number of points sampled per week for the wave; N p is the delayed data point; f s is the grid frequency; T s is the response time of the calculated dynamic compensation device, and the unit of this response time is ms.

Images