Study On Voltage Sudden Change Detection Method And Its Application Based On Simplified K-S Decomposition Algorithm

With the continuous improvement of modern industrial level,more and more impact,non-linear and asymmetrical loads are injected into the power system,which leads a series of power quality problems.The voltage sudden-change is one of the important evaluation indexes of power quality.Because of its high frequency and large range of influence,even cause serious economic losses,it is getting more and more attention.The rapid and accurate detection of the voltage sudden-change characteristics is an important basis for the interference location of voltage sudden-change,analysis of effect,and improvement of governance.Therefore,it has great theoretical significance and application value to study the real-time detection method of voltage sudden-change and realize in the embedded hardware platform.Firstly,the significance of voltage sudden-change detection is expounded in this thesis,and the definition of voltage sudden-change,the causes and the harm caused are described,and the relevant standards at home and abroad are introduced.And the characteristics of existing detection methods and development status of detection device are analyzed.S-transform and its characteristics is briefly introduced,and the shortcomings of S-transform are analyzed.The energy distribution characteristics of time-frequency analysis algorithm are studied and analyzed,a frequency-dependent adaptive Kaiser window function is established.According to the Kaiser window which instead of Gaussian window in S-transform,a new time-frequency analysis algorithm is derived,which is the K-S decomposition.The derivation process is given in this thesis,and the algorithm is discretized,and the characteristics and computational process of K-S decomposition are studied by simulation experiment.Based on the feature frequency point extraction method,the K-S decomposition algorithm is simplified to reduce its computation and make it easy to be implemented in embedded hardware platform.The voltage sudden-change detection method based on K-S decomposition simplification algorithm is deeply studied.The accurate detection of the voltage sudden-change amplitude is achieved by combining the fundamental frequency amplitude curve with FFT method.The detection accuracy of start-stop moment and durations of sudden-change is improved by the fundamental frequency amplitude difference square curve,and the phase jump variable of voltage sudden-change is obtained from the fundamental frequency phase curve,and the voltage sudden-change detection process based on K-S decomposition simplification algorithm is provided.And simulation research experiments are performed under the cases of a variety of interferences in this thesis,and the result of simulation shows that the errors of the method is small,and the method has a good noise resistance.Combined with the proposed algorithm in this thesis and practical application requirements,an embedded voltage sudden-change detection system based on ADC+DSP architecture is designed.The design and implementation of data acquisition module,data processing module,communication interface module and power supply module for the hardware platform are introduced in this thesis.The software of detection method is implemented based on TI-RTOS real-time system,and the realization process of voltage sudden-change detection and fault wave record module are provided.Finally,the reliability of the detection system is analyzed,and the system is tested.The test results show that the system can well meet the demand of voltage sudden-change detection in power system.