Design And Development Of Power Quality Monitoring System For Wind Power Test-bed

In recent years,the continuous development of wind power technology and the rapid expansion of wind farm scale make the requirements of power quality in wind power integration higher and higher.With the development of wind turbine to large-scale,its internal structure is more complex,the test of wind turbine can be carried out by engineering test with high-power test-bed of wind power integration,in which the monitoring of power quality is the key part to evaluate the performance of the test bench.Therefore,this paper combined the theory and method of power quality and inverter impedance detection to design and develop a power quality monitoring system for wind power grid-connected test-bed.First of all,this paper analyzed the index and detection algorithm of steady-state power quality in wind power integration,as well as the identification and positioning method of transient power quality disturbance.The mathematical models of power quality perturbation were established by refering to the IEEE standard system.The disturbance characteristics were extracted by the methods of S transformation and wavelet packet transformation,PSO-ELM algorithm was proposed to classify and locate the power quality disturbance.Compared with the classification results of ELM and SVM,the effectiveness of PSO-ELM algorithm was verified.Secondly,the grid power impedance of the inverter will deteriorate the power quality of the system,which will affect the grid connection stability of the wind power system.Therefore,the impedance of the inverter grid was used as a monitoring indicator to monitor the operation status of the wind power grid-connected system.The model of three-phase grid-connected inverter and its grid impedance was established.The grid impedance of the inverter in the system was detected based on the method of discrete interval binary sequence injection,and the results of detection agree basically with the theoretical curve of the impedance.The hardware in-loop experiment based on the MT6000 simulator was constructed to verify the validity of the inverter grid impedance detection scheme.Based on the above research,this paper designed and developed a software and hardware system for power quality monitoring of wind power test-bed.This system used Hall-type sensors to collect power parameters such as voltage and current.The pre-amplification circuit of sampling data and anti-aliasing filter circuit were designed to filter out high-frequency components and restore the real signal to the maximum.The upper computer and lower computer software of the monitoring system were developed,the real-time acquisition module based on FPGA was designed in the slave computer program,then the module of the steady state power quality disturbance monitoring,the module of transient disturbance positioning and classification,and the module of inverter grid impedance monitoring were developed in the host computer.Finally,the design and development of the monitoring system and HIOKI 3390 power analyzer were used to monitor the power quality of the wind power test stand in real time,and the monitoring results were compared and analyzed to verify the accuracy of the power quality monitoring system.In order to verify the effectiveness of the transient power quality disturbance classification and positioning algorithm,faults data were generated through the model of power distribution system and the classification model was used for fault diagnosis.The experimental results showed that the fault classification and positioning is more accurate.The above experiments show that the design and development of the system can provide monitoring technical support for the smooth operation of the wind power system.