Studies On Synchronized Phasor Measurement System Oriented To Active Distribution Network

In recent years,with the rapid development of clean and renewable energy recently,a large number of distributed generation(DG)are constantly connected to the distribution network,so that the traditional distribution network structure and operation environment have become increasingly complex.To ensure the security and stable operation of the distribution network in the new situation,the concept of active distribution network(ADN)is proposed.Reliable method of monitoring,as the basic element of distribution network,plays the key role in measurement,protection and control.Nowadays,the monitoring unit based on synchronous phasor has been applied in high-level power transmission network.However,there are still many challenges in the practice of the device in active distribution network.The accuracy of measurement algorithm and the size of the device have the most impact.Some of the existing measurement algorithm can ensure higher measurement accuracy in the stable condition of power system.But when system disturbances and strong interference occurs,the accuracy of those methods can be greatly affected to meet the actual requirements.Therefore,studying the phasor measurement algorithm with high performance will be very important for the application of synchronous phasor measurement technology in the active distribution network in the future.This paper provides a measurement algorithm to solve those problems,and designs a synchronous phasor measurement device based on TMS320F2812 with the new algorithm,the main contents are as follows:Firstly,this paper introduces the principle of synchronous phasor and the main synchronous phasor measurement algorithm,and expounds the factors that can restrict the accuracy and practical application of various synchronous phasor measurement algorithm.Then the paper takes the relevant literature at home and abroad for reference,and analyzes the improvement of the researchers are presented.Secondly,the thesis proposes a synchronous phasor measurement based on FFT spectral line interpolation.The spectral leakage problem of FFT in non-synchronous sampling can be restrained by using of the good amplitude frequency characteristics of the new Nuttall-Kaiser combination of window,then the measurement result can be corrected by spectral line interpolation.The simulation tests show that the algorithm can suppress spectral leakage,harmonic effect and noise effectively,which has the high accuracy of frequency and phasor measurement.It is suitable for the synchronous phasor measurement system with low real-time requirements.Thirdly,a new method of synchronized phasor measurement algorithm based on the improved DFT is put forward to meet the requirement of high real-time system.The method firstly uses two groups of phasor measurement results which of adjacent sequence to track the signal frequency.Then,the DFT synchronous phasor measurement algorithm under the condition of non-synchronous sampling is modified by tracking frequency.Finally,it realizes the accurate measurement of frequency,amplitude and phasor.The signal models under different conditions are established by MATLAB.The simulation results show that the algorithm has good performance in different disturbance condition.Finally,on the basis of the high real-time measurement algorithm,a synchronized phasor measurement device based on TMS320F2812 is produced by using of the reasonable hardware selection and software design.The device has the advantages of small size,good measurement precision,anti-interference ability and real-time performance,and it can meet the requirements of the application and development of the active distribution network in the future.