Research On Hybrid Measurements State Estimation Method For Distribution Networks Based On Quadratic Contraint Quadratic Estimation

With the development of China's smart distribution network and the improvement of users'power quality requirements,power companies have put forward higher requirements for real-time monitoring and online analysis and decision-making control level of distribution network operation status.Distribution network state estimation is an important part of the distribution management system,and also the data foundation of other advanced application software,which is of great significance for ensuring the safe and economic operation of the distribution network.How to comprehensively consider the structural characteristics and quantity measurement types and characteristics of the distribution network,improve the state estimation performance and the accuracy of the results become the research focus of the three-phase state estimation of the distribution network.This paper is based on PMU and SCADA hybrid measurements,as well as QCQE model.The three-phase state estimation method of the distribution network has been studied.The main work is as follows:1)Study the model and algorithm of quadratic constraint quadratic estimation method.Based on the mathematical model of QCQE,it analyzes the sparsity,the extensibility and versatility of the sparse QCQE method.Furthermore,describe the state estimation problem as QCQE model,and then solve the model by traditional state estimator,analyzing the calculation ideas and summarizing the characteristics of the algorithm.2)Study the PMU/SCADA hybrid measurements model.Based on the characteristics and basic principles of phasor measurement,the three-phase phasor measurement model of the distribution network under the Cartesian coordinate system is established.And study the actual three-phase system measurement type and physical quantity measurement characteristics.3)Study the three-phase state estimation model of distribution network based on QCQE model.Based on the node injection current equation and the characteristics of the hybrid measurement,the measurement model of the quadratic equation in the Cartesian coordinate system is established.The problem is described as a QCQE problem and solved using mature state estimation algorithms.The case studies on three-phase balanced and three-phase unbalanced distribution network demonstrate the effectiveness and practicability.