Research On Optimal Configuration Of Distribution Network Measurement System Considering Risk

With the development of smart distribution network,distributed power sources and flexible loads are constantly connected,which makes the distribution network gradually transition from the traditional one-way flow mode to the active distribution mode,thus greatly affecting the reliability of the distribution network and putting forward higher requirements for the operation monitoring level of the distribution network.The synchronous phase measurement unit provides reliable measurement data for the operation monitoring and control of the distribution network by virtue of its real-time and accuracy.However,considering the high cost,the configuration of synchronous phase measurement units still needs to be studied in depth.In this paper,the optimal configuration of synchronous phase measurement units for distribution networks is investigated,and the main work is as follows:(1)The observability of the distribution network and the state estimation model of the distribution network are studied.Then the basic principles of state estimation are introduced,along with the mathematical description of the power system’s measurement system,and the weighted least squares method for static state estimation is introduced.In addition,the state estimation of nodal voltage phases in polar coordinate form,the state estimation of nodal voltage phases in right-angle coordinate form and the state estimation of branch current phases in right-angle coordinate form are studied.(2)The basic PMU optimal configuration model is established based on the system observability,while the PMU optimal configuration model considering line faults is established from the perspective of probability,in which the reliability of PMU equipment,communication lines,voltage sensors,current sensors,and transmission lines are considered.Then the node observable probability and system observable probability are defined,and the node observable probability calculation under normal condition and considering line fault condition is analyzed.Finally,a multi-objective PMU optimal configuration model is developed and solved using the NGSA-Ⅱ algorithm.Simulation calculations are performed for the IEEE 33-node system to verify the effectiveness of the proposed method.(3)A multi-objective PMU optimal configuration model considering the number of PMU configurations and state estimation error is developed to minimize the number of PMU configurations while reducing the state estimation error to ensure the comprehensiveness of the PMU configuration solution.An improved whale optimization algorithm is used to solve the optimal configuration model,and the Levy flight strategy is introduced to perturb the spiral update position pattern of the whale optimization algorithm in a variational manner,which makes the algorithm less likely to fall into local optimum by improving the position update pattern.Simulations are performed for the IEEE 33-node system to verify the effectiveness of the adopted improved whale optimization algorithm.