Model Of Total Supply Capability And Security Region For Flexible Distribution Network

Traditional distribution network(TDN)is designed in closed loop and operated in open loop due to the limitations of short circuit current control,electromagnetic loop,etc.This operation mode is facing a number of challenges such as short-term power supply interruption,low utilization rate of equipment,limited system reliability,etc.With the development of power electronics technology,flexibility of power electronics is an important trend in the development of urban distribution network in the future,it's hopeful to solve the related bottleneck problems in the open loop operation.This paper studies the flexible distribution network(FDN)with the power electronics,the main content is as follows:1.The concept,morphology,operation mode,security analysis method of FDN is presented.Firstly,the paper introduces the concept of FDN and flexible switching station(FSS),the key grid equipment of FDN.Then,the morphology of FDN is discussed and approaches to upgrade conventional distribution networks into FDNs are proposed.Meanwhile,the paper gives a specific morphology of FDN based on the present model of typical overhead line and cable distribution network.Next,there is a discussion about operation modes of FDN in three conditions,normal operation,N-1 contingency and maintenance.And a method on N-1 security assessment of FDN is proposed.Finally,in contrast with TDN,the quantitative calculation and analyses on FDN in normal operation and N-1 operation are made through an example.2.The model of total supply capability(TSC)is proposed.Firstly,the N-1 flexible load transfer strategy is analyzed.Secondly,the model of TSC is proposed.Then the solution algorithm of TSC for FDN is also presented.Finally,in contrast with TDN,the proposed model and solution algorithm are tested through a typical FDN of different scenarios.3.The model of security region for FDN is proposed.Firstly,the normal operation N-0/N-1 security constraints are discussed.Secondly,security region for FDN is modeled and the region boundary formulations are also proposed.Finally,the N-0/N-1 security region and supply capability of FDN and TDN are studied with single-and multi-connection cases,results show the correctness of the proposed method.4.Establish FDN security check and TSC calculation software module.Firstly,according to software module requirements of key technologies of AC/DC hybrid distribution network(2015AA050102)of the national high technology research and development program of China(863 Program),the programming environment and the input/output files are determined.Secondly,according to the security check method and the TSC model,module development framework and scheme are given.Finally,the software module is tested and the output results are displayed.