Research On Distribution Network PMU Configuration Scheme Based On Parameter Estimation Accuracy

As one of the infrastructure of modern industry,power system is very important for the stable development of social economy.The dynamic behavior of the distribution network is more complex than that of the transmission network.The multi-source and bidirectional flow of fault current and the increase of power electronic devices will cause the oscillation phenomenon of the distribution network.Therefore,it is necessary to monitor and control the existing distribution network in real time.The distribution network model based on the accurate line parameters of the power system is the basis to achieve the above goals.At present,the transformation cycle of distribution network is short and the equipment is updated frequently.In addition,the parameters of components are easy to be affected by the environmental conditions such as atmospheric temperature,so it is of great significance to analyze the changes of operation parameters of distribution network in real time to improve the analysis and operation level.With the rise of synchronous measurement unit(PMU)in the national distribution network,the scale of high-precision and high-density synchronous measurement data provided by PMU is gradually increasing,which provides a reliable way to establish a high reliability line parameter identification method based on measurement data.Therefore,for the study of parameter identification of distribution network,not only the traditional data acquisition method based on SCAD A,but also the PMU measurement data suitable for distribution network should be introduced.On the basis of SCADA measurement,combining with PMU data to establish the parameter identification model of distribution network in complex network,and further reasonable selection of distribution points to configure PMU to correct the identification error is an urgent research content.Based on the mixed multi-period measurement information of PMU and SCADA at both ends of the distribution network,and considering the topological structure and temperature environmental impact of the distribution network,this paper proposes a PMU configuration method aiming at improving the accuracy of the overall line parameters of the distribution network.The specific research contents are as follows:(1)On the basis of the existing parameter identification research,the physical equivalent model of the components and the topological structure of the distribution network are analyzed.According to the network structure,the nodes are divided into three categories.Starting from the two aspects of node solution and extended network solution,the parameters to be estimated and observability analysis of the distribution network in the configuration of PMU are carried out,and the comprehensive identification model of electric system line parameters based on the mixed multi-period measurement of PMU/SCADA is established.At the same time,a numerical simulation model considering the measurement error of PMU is established.Based on the known line parameters,and the error levels under different PMU configuration schemes are analyzed theoretically and verified by simulation to determine the PMU configuration principles with different accuracy requirements for parameter estimation.(2)According to the relationship between line parameters and power flow in augmented parameter estimation,the concept of dominant parameters is given to reflect the accuracy of parameter identification,and the evaluation method of dominant parameters is constructed according to the dispersion index.On this basis,aiming at the comprehensive optimization of identification accuracy and configuration number,the fitness function is constructed by the dispersion index.Then,the configuration number and installation location of PMU are optimized by the improved genetic algorithm.Finally,the effectiveness of the algorithm is verified by the IEEE-33 node active distribution network model based on PSCAD/EMTDC.Furthermore,compared with different PMU configuration schemes,it shows that the algorithm has the advantages of reducing the identification error.(3)Based on the theory of electrothermal coordination,a method of temperature resistance correction for distribution network is proposed.The heat balance equation is integrated into the least square method of state estimation,and an extended Jacobian matrix circuit parameter correction algorithm considering the state vector is proposed.In this paper,the deviation between the measured values of SCADA and PMU and the line temperature is derived in detail.And the Jacobian matrix is extended to make the line temperature and node state quantity can be calculated at the same time,which effectively corrects the line resistance value of the whole distribution network.Because the heat balance equation can be easily integrated into the existing software.In this paper,the parameter correction module considering the electrothermal coordination is combined with the PMU configuration algorithm,and is added to the state estimation correction.Then,a complete PMU configuration algorithm considering the accuracy of parameter identification under the influence of temperature is formed.