Impedance scanning method and system based on RTDS

Abstract

The invention relates to the technical field of RTDS real-time simulation, in particular to an impedance scanning method and system based on RTDS, and the method comprises the steps: inputting the maximum scanning frequency, frequency interval and harmonic voltage peak value of impedance scanning and the operation time of single harmonic impedance scanning into an impedance scanning device; building a real-time simulation module of the tested circuit; a real-time simulation module in the NovaCor is operated; operating the impedance scanning device; executing impedance scanning calculation; and obtaining an impedance scanning result. The system has the advantages that through the integrated impedance scanning device and the RTDS real-time simulator, the whole-process automation from parameter input to result output is realized, and the operation difficulty and the labor cost are greatly reduced; the impedance scanning efficiency and accuracy are improved, impedance scanning of a large number of frequency points can be completed in a short time through accurate parameter setting and an efficient algorithm, meanwhile, the result accuracy is guaranteed, and the method is undoubtedly and greatly improved for an electric power system needing frequent impedance analysis.

Description

Technical Field

[0001] The present invention relates to the technical field of RTDS real-time simulation, and in particular to an impedance scanning method and system based on RTDS. Background Art

[0002] With the rapid development of new energy generation technology, the penetration rate of renewable energy such as wind power and photovoltaics in the power grid continues to increase. However, the interaction between new energy generation devices and the power grid, as well as the influence of complex control strategies within the power grid, has led to frequent broadband oscillation problems, posing a serious threat to the stable operation of the power system.

[0003] Traditional impedance testing methods, such as theoretical analysis and simulation scanning, have many limitations when dealing with high-order systems, complex control strategies, and systems that are difficult to model. Therefore, a more efficient and accurate impedance scanning system is needed to accurately analyze the response of the power system in different disturbance frequency bands.

[0004] As an advanced real-time simulation tool for power systems, RTDS (Real Time Digital Simulator) has the advantages of convenient model construction, multiple system models, and repeatable reproduction of similar fault conditions. However, the existing RTDS system has not developed real-time impedance scanning functions and equipment for complex circuits (power electronic circuits such as wind power, photovoltaics, and DC transmission). At present, impedance scanning of complex circuits using RTDS can only be performed manually and at a single frequency. However, in order to ensure the practicality of the impedance scanning results, thousands of impedance scanning calculations are required. Faced with such a large and complex impedance scanning calculation, manual operation not only has problems such as low efficiency, but also may have cumbersome and complicated operations, resulting in inaccurate impedance scanning results, and cannot directly meet the needs of power system impedance testing. Summary of the invention

[0005] The purpose of the present invention is to provide an impedance scanning method and system based on RTDS, which utilizes RTDS to automatically perform impedance scanning of complex circuits, reduce the operational difficulty of RTDS impedance scanning, and improve the efficiency and accuracy of impedance scanning.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] An impedance scanning method based on RTDS, the impedance scanning process is as follows:

[0008] Enter the maximum scanning frequency f of the impedance scan in the impedance scanning device. max , frequency interval Δf, harmonic voltage peak value U peak and the running time t of a single harmonic impedance sweep;

[0009] A real-time simulation module of the circuit under test is built in the RTDS hardware simulation platform NovaCor, and a controlled voltage source is connected in series at the port of the circuit under test. The controlled voltage source is used to generate the harmonic voltage required for impedance scanning at the port of the circuit under test.

[0010] Run the real-time simulation module in NovaCor;

[0011] Running an impedance scanning device;

[0012] Perform impedance sweep calculations;

[0013] Obtain impedance scan results.

[0014] Impedance scan calculations, including:

[0015] Calculate the maximum number of scans n, the formula is as follows;

[0016] n=f max / Δf①

[0017] The number of scans increases from 1, and the time of each scan is t;

[0018] Perform a k-th impedance scan for each scan, where k=1, 2, 3, ..., n;

[0019] The harmonic impedances Z1, Z2, Z3, ..., Zn of each impedance scan are obtained.

[0020] The kth impedance scan includes:

[0021] The impedance scanning device sends out the harmonic voltage control signal Uk of the kth impedance scanning, and the peak value Uk of the harmonic voltage Uk is peak Size is U peak , the formula for harmonic voltage frequency fk is as follows:

[0022] fk=f min +(k-1)*Δf②

[0023] In formula ②, f min Indicates the minimum impedance scanning frequency;

[0024] The gigabit analog input board GTAI receives the harmonic voltage control signal Uk;

[0025] NovaCor receives the harmonic voltage control signal Uk transmitted by the gigabit analog input board GTAI and uses it as the control signal of the controlled voltage source in the real-time simulation module;

[0026] The Gigabit analog output board GTAO collects the voltage signal U and current signal I of the circuit under test in the real-time simulation module;

[0027] The impedance scanning device receives the voltage signal U and the current signal I sent by the gigabit analog output board GTAO;

[0028] The impedance scanning device stores the voltage signal U and the current signal I data with a duration of t;

[0029] The impedance scanning device uses the stored voltage signal U and current signal I data to perform Fourier decomposition to obtain the peak value Uk of the harmonic voltage signal of the kth impedance scan. peak , phase θk U And the peak value Ik of the harmonic current signal peak , phase θk I ;

[0030] Calculate the impedance peak value Zk of the kth impedance scan of the measured circuit peak and phase θk Z , the harmonic impedance Zk of the kth impedance scan is obtained, and the formula is as follows:

[0031] Z peak =Uk peak / Ik peak ③

[0032] θk Z =θk U -θk I ④

[0033] Zk=Z kpeak <θk Z ⑤

[0034] The impedance scanning device clears the voltage signal U and the current signal I data of the k-th impedance scanning, and stores the harmonic impedance Zk of the k-th impedance scanning.

[0035] The impedance scanning system based on RTDS comprises an impedance scanning device and an RTDS real-time simulator. The RTDS real-time simulator receives a harmonic voltage signal from the impedance scanning device and outputs a voltage signal and a current signal to the impedance scanning device.

[0036] The impedance scanning device includes a controller and a memory. The controller is connected to the memory. The controller is used to calculate harmonic impedance and output harmonic voltage signals. The memory is used to store voltage signals, current signals and system impedance of the circuit under test.

[0037] The RTDS real-time simulator includes the hardware simulation platform NovaCor, the gigabit analog output board GTAO, and the gigabit analog input board GTAI. The hardware simulation platform NovaCor is used to build a real-time simulation module for the circuit under test. The gigabit analog output board GTAO is used to output the voltage signal and current signal of the circuit under test in NovaCor and transmit them to the impedance scanning device. GTAI is used to receive the harmonic voltage signal output by the impedance scanning device and transmit it to the hardware simulation platform NovaCor.

[0038] The circuits under test are equivalent circuits of wind power generation systems, photovoltaic power generation systems, DC transmission systems, and power grids, and are built as real-time simulation modules in the hardware simulation platform NovaCor.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. Significantly improve the automation level of impedance scanning. Traditional impedance scanning requires manual parameter setting, process monitoring and result analysis. The present invention realizes full automation from parameter input to result output through an integrated impedance scanning device and RTDS real-time simulator, greatly reducing the difficulty of operation and labor costs.

[0041] 2. Improve the efficiency and accuracy of impedance scanning. Through precise parameter settings and efficient algorithms, impedance scanning of a large number of frequency points can be completed in a short time while ensuring the accuracy of the results. This is undoubtedly a huge improvement for power systems that require frequent impedance analysis.

[0042] 3. It also enhances the stability and security of the power system. By real-time monitoring and analyzing the impedance characteristics of the measured circuit, it can promptly detect potential faults and problems, providing strong support for the maintenance and optimization of the power system. In addition, it can also be applied to different types of power systems, such as wind power generation, photovoltaic power generation and DC transmission, providing strong guarantees for the diversified development of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the impedance scanning system based on RTDS.

[0044] Figure 2 This is the impedance scanning flow chart based on RTDS.

[0045] Figure 3 This is the impedance scan calculation flow chart based on RTDS.

[0046] Figure 4 This is the k-th impedance scan flow chart based on RTDS. DETAILED DESCRIPTION

[0047] The present invention is described in detail below in conjunction with the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0048] The following examples are implemented on the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.

[0049] Example 1

[0050] An impedance scanning system based on RTDS, see Figure 1 , an impedance scanning device and an RTDS real-time simulator, the RTDS real-time simulator receives the harmonic voltage signal from the impedance scanning device, and outputs the voltage signal and the current signal to the impedance scanning device; the impedance scanning device includes a controller and a memory, the controller is connected to the memory, the controller is used to calculate the harmonic impedance and output the harmonic voltage signal, the memory is used to store the voltage signal, the current signal and the system impedance of the circuit under test; the RTDS real-time simulator includes a dedicated hardware simulation platform NovaCor, a gigabit analog output board GTAO, and a gigabit analog input board GTAI, NovaCor is used to build a real-time simulation module for the circuit under test, the circuit under test is an equivalent circuit of a wind power generation system, a photovoltaic power generation system, a DC transmission system, and a power grid, and is built in NovaCor as a real-time simulation module; the gigabit analog output board GTAO is used to output the voltage signal and the current signal of the circuit under test in NovaCor and transmit them to the impedance scanning device, and GTAI is used to receive the harmonic voltage signal output by the impedance scanning device and transmit it to NovaCor.

[0051] An impedance scanning method based on RTDS, see Figure 2 -Figure,4,Impedance scanning process, the content is as follows:

[0052] S1. Input the maximum scanning frequency f of impedance scanning in the impedance scanning device. max , frequency interval Δf, harmonic voltage peak value U peak and the running time t of a single harmonic impedance sweep;

[0053] S2. Build a real-time simulation module of the circuit under test in the RTDS hardware simulation platform NovaCor, and connect a controlled voltage source in series at the port of the circuit under test. The controlled voltage source is used to generate the harmonic voltage required for impedance scanning at the port of the circuit under test.

[0054] S3, run the real-time simulation module in NovaCor;

[0055] S4, running the impedance scanning device;

[0056] S5. Execute impedance scan calculation, including:

[0057] S51, calculate the maximum number of scans n, the formula is as follows;

[0058] n=f max / Δf①

[0059] S52, increasing the number of scans from 1, each scan time is t;

[0060] S53, performing a k-th impedance scan for each scan, where k=1, 2, 3, ..., n, including:

[0061] 1) The impedance scanning device sends out the harmonic voltage control signal Uk of the kth impedance scanning, and the peak value Uk of the harmonic voltage Uk is peak Size is U peak , the formula for harmonic voltage frequency fk is as follows:

[0062] fk=f min +(k-1)*Δf②

[0063] In formula ②, f min Indicates the minimum impedance scanning frequency;

[0064] 2) The gigabit analog input board GTAI receives the harmonic voltage control signal Uk;

[0065] 3) NovaCor receives the harmonic voltage control signal Uk transmitted by the gigabit analog input board GTAI and uses it as the control signal of the controlled voltage source in the real-time simulation module;

[0066] 4) The Gigabit analog output board GTAO collects the voltage signal U and current signal I of the circuit under test in the real-time simulation module;

[0067] 5) The impedance scanning device receives the voltage signal U and the current signal I sent by the gigabit analog output board GTAO;

[0068] 6) The impedance scanning device stores the voltage signal U and the current signal I data with a duration of t;

[0069] 7) The impedance scanning device uses the stored voltage signal U and current signal I data to perform Fourier decomposition to obtain the peak value Uk of the harmonic voltage signal of the kth impedance scan. peak , phase θk U And the peak value Ik of the harmonic current signal peak , phase θk I ;

[0070] 8) Calculate the impedance peak value Zk of the kth impedance scan of the measured circuit peakand phase θk Z , the harmonic impedance Zk of the kth impedance scan is obtained, and the formula is as follows:

[0071] Z peak =Uk peak / Ik peak ③

[0072] θk Z =θk U -θk I ④

[0073] Zk=Z kpeak <θk Z ⑤

[0074] 9) The impedance scanning device clears the voltage signal U and current signal I data of the k-th impedance scanning, and stores the harmonic impedance Zk of the k-th impedance scanning.

[0075] S54, obtaining the harmonic impedances Z1, Z2, Z3, ..., Zn of each impedance scan.

[0076] S6. Obtain impedance scanning results.

[0077] Example 2

[0078] In this embodiment, an impedance scanning method and system based on RTDS are the same as those in Embodiment 1, and an actual application process is added thereto.

[0079] Background of the embodiment: A certain place needs to perform impedance scanning on the equivalent circuit of a wind power generation system to evaluate its impedance characteristics at different frequencies. The system includes components such as generators, transformers, and transmission lines, and its equivalent circuit model has been built on the NovaCor platform of RTDS.

[0080] Implementation steps include:

[0081] 1. Parameter settings

[0082] In the impedance scanning device, set the maximum scanning frequency f max is 10kHz, the frequency interval Δf is 100Hz, and the harmonic voltage peak value U peak is 200V, and the running time t of a single harmonic impedance scan is 1 second;

[0083] Set the minimum impedance scanning frequency f min is 100Hz.

[0084] 2. Build simulation module

[0085] On the NovaCor platform, the equivalent circuit model of the wind power generation system is imported;

[0086] A controlled voltage source is connected in series at the port of the circuit under test to generate harmonic voltage.

[0087] 3. Run simulation and scan

[0088] Start the real-time simulation module in NovaCor and begin simulating the operation of the wind power generation system;

[0089] Start the impedance scanning device and begin to perform impedance scanning according to the set parameters.

[0090] 4. Impedance calculation and storage

[0091] For each scan, the impedance scanning device sends out a harmonic voltage control signal Uk, which is transmitted to NovaCor via GTAI;

[0092] NovaCor uses the harmonic voltage control signal as the control signal of the controlled voltage source to generate the corresponding harmonic voltage;

[0093] GTAO collects the voltage signal U and current signal I of the circuit under test and transmits them to the impedance scanning device;

[0094] The impedance scanning device performs Fourier decomposition on the received voltage and current signals to calculate the peak values ​​and phases of the harmonic voltage and current;

[0095] Calculate the impedance peak value Zk of the kth impedance scan of the measured circuit according to the formula peak and phase θ kZ , and obtain the harmonic impedance Zk;

[0096] The calculated harmonic impedance Zk is stored in the memory of the impedance scanning device.

[0097] 5. Result analysis:

[0098] After completing the impedance scan of all frequency points, the impedance scanning device exports the stored harmonic impedance data to the analysis software;

[0099] The analysis software processes and analyzes the exported data to generate an impedance-frequency characteristic curve graph;

[0100] By observing and analyzing the impedance-frequency characteristic curve, the impedance characteristics of the wind power generation system at different frequencies can be evaluated, providing strong support for the stable operation and fault analysis of the system.

[0101] Implementation effect: Through this embodiment, we have successfully used the impedance scanning method and system based on RTDS to perform impedance scanning on the equivalent circuit of the wind power generation system; not only the automation and efficiency of the impedance scanning are improved, but also the accuracy of the scanning results is guaranteed; at the same time, it can also be applied to other types of power systems, such as photovoltaic power generation, DC transmission, etc., to provide a strong guarantee for the stable operation and fault analysis of the power system.

[0102] Example 3

[0103] In this embodiment, an impedance scanning method and system based on RTDS are the same as those in Embodiment 1, and an embodiment targeting a photovoltaic power generation system is added on the basis of Embodiment 1 and / or Embodiment 2.

[0104] Embodiment Background: When evaluating the impedance characteristics of a photovoltaic power generation system at different frequencies to ensure its stability and compatibility when connected to the grid, the equivalent circuit model of the photovoltaic power generation system has been built on the NovaCor platform of RTDS and is ready for impedance scanning.

[0105] Implementation steps:

[0106] 1. Parameter configuration

[0107] In the impedance scanning device, set the maximum scanning frequency f max is 5kHz, the frequency interval Δf is 50Hz, and the harmonic voltage peak value U peak The voltage was set to 150 V, and the running time t of a single scan was set to 0.5 seconds;

[0108] Determine the minimum impedance scanning frequency f min is 50Hz.

[0109] 2. Build real-time simulation

[0110] Import the equivalent circuit model of the photovoltaic power generation system on the NovaCor platform. The model includes key components such as photovoltaic cell arrays, inverters, filters and transmission lines.

[0111] A controlled voltage source is connected in series to the system output port to generate the required harmonic voltage during the impedance scanning process.

[0112] 3. Start the scanning process

[0113] Run the real-time simulation module in NovaCor to simulate the actual operation of the photovoltaic power generation system;

[0114] Activate the impedance scanning device and start the impedance scanning task according to the preset parameters.

[0115] 4. Data collection and processing

[0116] The impedance scanning device sends a harmonic voltage control signal Uk to NovaCor via GTAI;

[0117] NovaCor converts the received control signal into an excitation signal for a controlled voltage source, thereby generating harmonic voltage at the output port of the photovoltaic power generation system;

[0118] GTAO is responsible for collecting the voltage signal U and current signal I of the photovoltaic power generation system, and transmitting these data to the impedance scanning device in real time;

[0119] The impedance scanning device performs Fourier decomposition on the received signal to extract the peak value and phase information of the harmonic voltage and harmonic current;

[0120] Calculate the impedance peak value Zk for each scan according to the formula peak and phase θk Z , get the complete harmonic impedance Zk data;

[0121] The calculated impedance data is stored in the memory of the impedance scanning device for subsequent analysis.

[0122] 5. Results analysis and application

[0123] After the scan is completed, the stored impedance data is exported to professional data analysis software;

[0124] The exported impedance data is processed using data analysis software to generate an impedance-frequency characteristic curve graph;

[0125] By observing and analyzing the impedance characteristic curve, the impedance stability of the photovoltaic power generation system at different frequencies and its compatibility with other power equipment can be evaluated;

[0126] According to the analysis results, necessary adjustments and optimizations can be made to the photovoltaic power generation system to improve the stability and efficiency of its grid-connected operation.

[0127] Implementation effect: The impedance scanning method and system based on RTDS were successfully applied to the impedance characteristic evaluation of photovoltaic power generation systems; it not only improved the automation and accuracy of impedance scanning, but also significantly reduced the complexity and cost of manual operation; at the same time, it provided strong technical support for the grid-connected operation of photovoltaic power generation systems, which helped to improve the stability and reliability of the entire power system; in addition, it is also applicable to other types of power systems, such as wind power generation, DC transmission, etc., providing a strong guarantee for the comprehensive impedance analysis of power systems.

[0128] The present invention significantly improves the automation level of impedance scanning. Traditional impedance scanning requires manual parameter setting, process monitoring and result analysis. The present invention realizes full automation from parameter input to result output through an integrated impedance scanning device and an RTDS real-time simulator, greatly reducing the difficulty of operation and labor costs; improves the efficiency and accuracy of impedance scanning. Through precise parameter setting and efficient algorithms, impedance scanning of a large number of frequency points can be completed in a short time while ensuring the accuracy of the results. This is undoubtedly a huge improvement for power systems that require frequent impedance analysis; it also enhances the stability and safety of the power system. Through real-time monitoring and analysis of the impedance characteristics of the circuit under test, potential faults and problems can be discovered in time, providing strong support for the maintenance and optimization of the power system. In addition, it can also be applied to different types of power systems, such as wind power generation, photovoltaic power generation and direct current transmission, providing a strong guarantee for the diversified development of the power system.

Claims

1. An impedance scanning method based on RTDS, characterized in that: The impedance scanning process is as follows: Enter the maximum scanning frequency f of the impedance scan in the impedance scanning device. max , frequency interval Δf, harmonic voltage peak value U peak and the running time t of a single harmonic impedance sweep; A real-time simulation module of the circuit under test is built in the RTDS hardware simulation platform NovaCor, and a controlled voltage source is connected in series at the port of the circuit under test. The controlled voltage source is used to generate the harmonic voltage required for impedance scanning at the port of the circuit under test. Run the real-time simulation module in NovaCor; Running an impedance scanning device; Perform impedance sweep calculations; Obtain impedance scan results.

2. The impedance scanning method based on RTDS according to claim 1, characterized in that: The impedance scanning calculation includes: Calculate the maximum number of scans n, the formula is as follows; n=f max / Δf①Increase the number of scans from 1, and the time of each scan is t; Perform a k-th impedance scan for each scan, where k=1, 2, 3, ..., n; The harmonic impedances Z1, Z2, Z3, ..., Zn of each impedance scan are obtained.

3. The impedance scanning method based on RTDS according to claim 2, characterized in that: The kth impedance scan comprises: The impedance scanning device sends out the harmonic voltage control signal Uk of the kth impedance scanning, and the peak value Uk of the harmonic voltage Uk is peak Size is U peak , the formula for harmonic voltage frequency fk is as follows: fk=f min +(k-1)*Δf②In formula ②, f min Indicates the minimum impedance scanning frequency; The gigabit analog input board GTAI receives the harmonic voltage control signal Uk; NovaCor receives the harmonic voltage control signal Uk transmitted by the gigabit analog input board GTAI and uses it as the control signal of the controlled voltage source in the real-time simulation module; The Gigabit analog output board GTAO collects the voltage signal U and current signal I of the circuit under test in the real-time simulation module; The impedance scanning device receives the voltage signal U and the current signal I sent by the gigabit analog output board GTAO; The impedance scanning device stores the voltage signal U and the current signal I data with a duration of t; The impedance scanning device uses the stored voltage signal U and current signal I data to perform Fourier decomposition to obtain the peak value Uk of the harmonic voltage signal of the kth impedance scan. peak , phase θk U And the peak value Ik of the harmonic current signal peak , phase θk I ; Calculate the impedance peak value Zk of the kth impedance scan of the measured circuit peak and phase θk Z , the harmonic impedance Zk of the kth impedance scan is obtained, and the formula is as follows: Zk peak =Uk peak / I peak ③ θk Z =θk U -θk I ④ Zk=Z kpeak <θk Z ⑤ The impedance scanning device clears the voltage signal U and the current signal I data of the k-th impedance scanning, and stores the harmonic impedance Zk of the k-th impedance scanning.

4. An impedance scanning system based on RTDS for implementing the method described in claims 1-3, characterized in that: The system comprises an impedance scanning device and an RTDS real-time simulator. The RTDS real-time simulator receives a harmonic voltage signal from the impedance scanning device and outputs a voltage signal and a current signal to the impedance scanning device.

5. The impedance scanning system based on RTDS according to claim 4, characterized in that: The impedance scanning device includes a controller and a memory. The controller is connected to the memory. The controller is used to calculate harmonic impedance and output harmonic voltage signals. The memory is used to store voltage signals, current signals and system impedance of the circuit under test.

6. The impedance scanning system based on RTDS according to claim 4, characterized in that: The RTDS real-time simulator includes a hardware simulation platform NovaCor, a gigabit analog output board GTAO, and a gigabit analog input board GTAI. The hardware simulation platform NovaCor is used to build a real-time simulation module for the circuit under test. The gigabit analog output board GTAO is used to output the voltage signal and current signal of the circuit under test in NovaCor and transmit them to an impedance scanning device. GTAI is used to receive the harmonic voltage signal output by the impedance scanning device and transmit it to the hardware simulation platform NovaCor.

7. The impedance scanning system based on RTDS according to claim 6, characterized in that: The circuit under test is an equivalent circuit of a wind power generation system, a photovoltaic power generation system, a direct current transmission system, and a power grid, and is built as a real-time simulation module in the hardware simulation platform NovaCor.

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