State Estimation And Power Supply Capacity Evaluation Of Medium Voltage Distribution Network

With the development of distributed generation,electric vehicles,and demand-side response technologies,power companies put forward higher requirements for the robustness and reliability of distribution network.On one hand,in order to achieve real-time monitoring and management of distribution network,it is necessary to estimate the operating status of each component accurately and quickly.On the other hand,the distribution network needs to provide sufficient acceptance and adjustment capabilities to access of large-scale distributed generators and load.As the intermediate part of distribution network,the mid-voltage distribution network has a flexible topology and a wide range of application scenarios.To better adapt to the increase of load and rapid changes in operating status,it is needed to be expanded from the perspective of optimization and operation.This paper has researched the real-time state estimation and total supply capacity evaluation of medium-voltage distribution network.The main work can be summarized as follows:1)Study the real-time state estimation model of mid-voltage distribution network.The lack of real-time measurements makes it difficult for the existing state estimation technology to be directly applied to actual distribution network.Based on the characteristics,which are the radial structure and considerable branches' current amplitude measurements,of medium-voltage distribution network,the observability analysis method is proposed.The system is divided into multiple observation regions by removing the observable branches,and a strategy for generating pseudo-measurements for those unmonitored nodes is given.On the basis of quadratic constraint quadratic estimation,a real-time state estimation model is established.It is shown that the model can realize effective state estimation even in distribution network with low redundancy.The speed and accuracy of the calculation can satisfy the requirements of basic application,and this technique has good application prospects in current mid-voltage distribution network.2)Study the evaluation methods of power supply capacity of medium voltage distribution network.According to the operating characteristics and load transfer constraints of typical mid-voltage feeders,this paper proposes the concept of ideal one-supply-standby structure,and directed graph is used to simplify the complex distribution networks.Based on the simplified directed topology diagrams of distribution network,the calculation method is discussed and analyzed from two perspectives,namely,the computer-based calculation method and the manual calculation method for engineering applications.The practicality of the calculation methods is demonstrated by an example.