Hardware Design And Algorithm Research Of Synchronous Phasor Measurement Device

Electric power industry is the basic industry of modern society.Due to its large size and complexity,it is difficult to fully monitor and reliably control the power quality.Real-time monitoring and accurate estimation of grid dynamics have become a necessary issue.In many applications,power systems need to measure phasor amplitude and angle in real time and determine the harmonics present in voltage and current signals.A wide area monitoring system(WAMS)based on phasor measurement data acquisition technology emerged at the historic moment,providing an opportunity for power grid operators to monitor the system in real time.WAMS is one of the latest grid monitoring and control methods recognized at home and abroad.Firstly,this thesis describes the research background and significance of phasor measurement technology.Based on the principle of phasor measurement and the development status of the measuring device at home and abroad,the phasor measurement algorithm is optimized.Three algorithms are proposed to improve the accuracy of phasor measurement.Designed and developed the hardware and software system of the phasor measurement device.And one of the improved algorithms is transplanted to the DSP,thereby improving the measurement accuracy of the phasor measurement device.The main research contents of this article are as follows:(1)On the basis of reviewing a large number of relevant domestic and foreign literatures,an in-depth research and analysis of the research background and significance on this subject were carried out.The domestic and foreign research status of synchronous phasor measurement devices and algorithms are analyzed and summarized.At the same time,the industry standards in the field of power systems are explained.(2)The method for estimating synchronous phase angle and frequency under steady-state and dynamic conditions is proposed.This algorithm is an improved method based on the weighted least squares taylor expansion fourier(WLS-TF)algorithm.The derivation process of the improved WLS-TF algorithm is introduced in detail,and a new method of frequency estimation using second-order polynomial interpolation function is proposed.Considering the different steady-state and dynamic signals in the signal model,the comparison shows the effectiveness of the proposed method.(3)A new adaptive block least mean square algorithm for estimating phasor parameters is proposed.The unknown phasor model is modeled as a linear filtering problem.Use second-order optimization techniques to estimate amplitude and phase.It does not require any matrix inversion operation and has less computational complexity.The convergence,fast response and accuracy of the algorithm are verified through simulation.(4)The phasor measurement devices based on DSP currently popularized in the market generally use the fast Fourier transform(FFT)as the data processing calculation method.Traditional discrete Fourier transform is used as the basic algorithm for phasor measurement in power system.Although the calculation is simple and has a certain ability to suppress harmonics,it is seriously affected by picket-fence effects and spectral leakage.To improve the fast and accurate measurement of power system phasors,an improved method based on discrete Fourier is proposed in this paper as well as compared with the first two algorithms in terms of the measurement accuracy.(5)The basic principle and overall framework of the synchronous measurement device are introduced.The influence of the synchronous time scale position on the phasor measurement is analyzed.It shows the importance of choosing the best position of the synchronization time scale for the phasor measurement device.A method of judging the best position of the time scale is proposed.(6)The hardware and software design of the phasor measurement device is introduced.The hardware circuit includes a data acquisition module,a data processing module,a synchronous time scale forming module,etc.The circuit schematic diagram of each module is given,and the selection of the module and related electrical characteristics are described.Based on the hardware circuit,the system program is designed in blocks.In order to improve the accuracy of power system phasor measurement,CCS3.3 software is used as the development platform,and the improved DFT algorithm is transplanted into DSP.(7)Commission and run the synchronous phasor measurement device.The accuracy of improved DFT algorithm transplantation is verified through the simulation in CCS3.3 environment.Test the overall running performance of the device with a standard sources.Set the voltage and current parameters of the standard source,and read the voltage and frequency information in the CCS environment.Finally,the whole device was debugged in the laboratory,and the output voltage and frequency were tested.