電流互感器飽和的檢測和補償?shù)认嚓P問題的研究
發(fā)布時間：2018-07-20 09:29
【摘要】：電力系統(tǒng)發(fā)生故障時，一次側(cè)電流可達負荷電流的幾十倍甚至上百倍，且含有一定分量的衰減直流偏移分量。在這種情況下，用于繼電保護和測量用的電流互感器鐵心會發(fā)生飽和，電流互感器不能準確傳變一次側(cè)電流，致使二次側(cè)電流發(fā)生畸變。進而影響繼電保護誤動作，同時由于測量誤差影響其它二次設備的正常運行。本論文就電流互感器飽和的相關問題進行了較為全面的研究，具體內(nèi)容如下。 1.簡要介紹電流互感器以及其數(shù)學模型，從理論和實際仿真兩個角度綜合研究一次電流波形、衰減直流偏移分量、二次側(cè)負載、鐵心剩磁、鐵心截面積、電流互感器變比以及電流互感器匝數(shù)等因素對電流互感器鐵心飽和情況的影響。 2.基于數(shù)學形態(tài)學理論，首次提出基于形態(tài)學梯度小波的電流互感器鐵心飽和檢測方法。由于電流互感器二次側(cè)畸變電流波形在進、出飽和點處梯度發(fā)生明顯變化，能夠?qū)﹄娏鞑ㄐ胃鞑蓸狱c處的梯度進行分析的形態(tài)學梯度小波方法結合形態(tài)學開-閉和高帽變換能夠準確檢測出電流互感器的進、出飽和點。仿真結果表明該檢測方法能夠準確檢測出不同故障情況下的飽和區(qū)間，并且具有較高的抗噪聲和抗諧波能力。此外，該方法具有計算量小、延時短以及較高可靠性和廣泛適用性的優(yōu)點。 3.首次提出基于提升形態(tài)學梯度和形態(tài)學分解的電流互感器鐵心飽和檢測方法。由于畸變電流波形在進、出飽和點處，梯度變化明顯，因此，基于對采樣點梯度分析的提升形態(tài)學梯度算法和形態(tài)學分解算法均能得出準確的檢測結果。最終檢測結果由以上兩種檢測算法的結果綜合分析得到。仿真結果表明該方法能夠準確檢測出不同故障情況下的飽和區(qū)間，并且具有運算量小、延時短、檢測精度高、適用范圍廣和可靠性高等優(yōu)點。 4.提出了基于線性回歸的二次側(cè)電流畸變補償方法。該方法基于上述電流互感器飽和檢測方法的檢測結果，利用未飽和區(qū)各采樣點的幅值分別計算飽和區(qū)各采樣點的基波分量幅值和衰減直流偏移分量幅值，實現(xiàn)對畸變電流的補償。與其它補償方法相比，該方法運算量小、補償精度高、實時性強、適用范圍廣，并且不引入截斷誤差。仿真結果表明該補償方法針對不同故障情況下的畸變電流均能實現(xiàn)準確的補償。 5.開發(fā)以現(xiàn)場可編程門陣列(FPGA)為核心的片上系統(tǒng)，并且在該片上系統(tǒng)實現(xiàn)了基于提升形態(tài)學梯度和形態(tài)學分解的鐵心飽和檢測方法。設計開發(fā)板硬件平臺和軟件平臺，搭建測試平臺，實現(xiàn)片上系統(tǒng)整體設計。實驗結果表明，，在該片上系統(tǒng)內(nèi)，檢測方法能夠有效發(fā)揮作用，且硬件、軟件平臺具有良好的可靠性和實用性。
[Abstract]:When the power system fails, the primary side current can reach tens or even hundreds times of the load current, and contains a certain component of the attenuated DC offset component. In this case, the core of the current transformer used for relay protection and measurement will be saturated, and the current transformer can not accurately transfer the primary current, resulting in distortion of the secondary side current. Then the relay protection maloperation is affected, and the normal operation of other secondary equipments is affected by the measurement error. In this paper, the saturation of current transformers is studied in detail, and the details are as follows. 1. The current transformer and its mathematical model are briefly introduced. The primary current waveform, attenuated DC offset component, secondary load, core remanence, core cross section area are comprehensively studied from both theoretical and practical simulation points. The influence of the current transformer ratio and the turn number of the current transformer on the saturation of the current transformer core. 2. Based on the mathematical morphology theory, a new method for detecting the core saturation of current transformer based on morphological gradient wavelet is proposed for the first time. The gradient at the saturation point of the secondary side of the current transformer changes obviously because the current waveform is in and out of the secondary side of the transformer. The morphological gradient wavelet method, which can analyze the gradient of each sampling point of the current waveform, can accurately detect the saturation point of the current transformer by combining the morphological opening and closing and the high cap transform. The simulation results show that the proposed method can accurately detect the saturation regions in different fault cases and has high anti-noise and anti-harmonic capability. In addition, the method has the advantages of less computation, shorter delay, higher reliability and wider applicability. A method for detecting iron core saturation of current transformer based on lifting morphological gradient and morphological decomposition is proposed for the first time. Because the distortion current waveform changes obviously at the point of entering and leaving the saturation point, the improved morphological gradient algorithm and morphological decomposition algorithm based on gradient analysis of sampling points can get accurate detection results. The final detection results are obtained by comprehensive analysis of the results of the above two detection algorithms. The simulation results show that this method can accurately detect the saturation interval in different fault cases, and has the advantages of small computation, short delay, high detection precision, wide application range and high reliability. 4. A linear regression based compensation method for secondary side current distortion is proposed. Based on the detection results of the above current transformer saturation detection method, the amplitude of the fundamental wave component and the decaying DC offset component of each sampling point in the unsaturated region are calculated by using the amplitude of the sample points in the unsaturated region. The compensation of distortion current is realized. Compared with other compensation methods, this method has the advantages of low computation, high compensation accuracy, high real-time performance, wide range of application and no truncation error. The simulation results show that the proposed compensation method can accurately compensate the distortion current in different fault cases. An on-chip system with field programmable gate array (FPGA) as the core is developed and the core saturation detection method based on lifting morphological gradient and morphological decomposition is implemented. Design development board hardware platform and software platform, build a test platform to achieve the overall design of the system on a chip. The experimental results show that the detection method can play an effective role in the system, and the hardware and software platform has good reliability and practicability.
【學位授予單位】：華南理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM452
本文編號：2133106
[Abstract]:When the power system fails, the primary side current can reach tens or even hundreds times of the load current, and contains a certain component of the attenuated DC offset component. In this case, the core of the current transformer used for relay protection and measurement will be saturated, and the current transformer can not accurately transfer the primary current, resulting in distortion of the secondary side current. Then the relay protection maloperation is affected, and the normal operation of other secondary equipments is affected by the measurement error. In this paper, the saturation of current transformers is studied in detail, and the details are as follows. 1. The current transformer and its mathematical model are briefly introduced. The primary current waveform, attenuated DC offset component, secondary load, core remanence, core cross section area are comprehensively studied from both theoretical and practical simulation points. The influence of the current transformer ratio and the turn number of the current transformer on the saturation of the current transformer core. 2. Based on the mathematical morphology theory, a new method for detecting the core saturation of current transformer based on morphological gradient wavelet is proposed for the first time. The gradient at the saturation point of the secondary side of the current transformer changes obviously because the current waveform is in and out of the secondary side of the transformer. The morphological gradient wavelet method, which can analyze the gradient of each sampling point of the current waveform, can accurately detect the saturation point of the current transformer by combining the morphological opening and closing and the high cap transform. The simulation results show that the proposed method can accurately detect the saturation regions in different fault cases and has high anti-noise and anti-harmonic capability. In addition, the method has the advantages of less computation, shorter delay, higher reliability and wider applicability. A method for detecting iron core saturation of current transformer based on lifting morphological gradient and morphological decomposition is proposed for the first time. Because the distortion current waveform changes obviously at the point of entering and leaving the saturation point, the improved morphological gradient algorithm and morphological decomposition algorithm based on gradient analysis of sampling points can get accurate detection results. The final detection results are obtained by comprehensive analysis of the results of the above two detection algorithms. The simulation results show that this method can accurately detect the saturation interval in different fault cases, and has the advantages of small computation, short delay, high detection precision, wide application range and high reliability. 4. A linear regression based compensation method for secondary side current distortion is proposed. Based on the detection results of the above current transformer saturation detection method, the amplitude of the fundamental wave component and the decaying DC offset component of each sampling point in the unsaturated region are calculated by using the amplitude of the sample points in the unsaturated region. The compensation of distortion current is realized. Compared with other compensation methods, this method has the advantages of low computation, high compensation accuracy, high real-time performance, wide range of application and no truncation error. The simulation results show that the proposed compensation method can accurately compensate the distortion current in different fault cases. An on-chip system with field programmable gate array (FPGA) as the core is developed and the core saturation detection method based on lifting morphological gradient and morphological decomposition is implemented. Design development board hardware platform and software platform, build a test platform to achieve the overall design of the system on a chip. The experimental results show that the detection method can play an effective role in the system, and the hardware and software platform has good reliability and practicability.
【學位授予單位】：華南理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM452
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