Control Method Of Coordinated Operation To Enhance Stability And Transfer Capability Of Multi-Level Electromagnetic Loop

At present the main network frame with 500kV lines for the main in China can not meet the increasing electricity demand and restricts the scale and ability of electricity transmission.In order to optimize the allocation of resources, we must accelerate the development of UHV lines so as to satisfy people's electricity demand. At the beginning of the UHV construction, however, UHV lines usually forms a number of multi-level electromagnetic loops with the existing 500 kV and 220 kV lines.When a high voltage grade line disconnects as a result of failure,power flow will shift to low voltage grade lines to a great extent, and it may cause a series of security and stability problems.Therefore, this article will focus on the stability and transmission capacity of multi-level electromagnetic loop.Firstly,based on the appearance of multi-level electromagnetic loop in the process of UHV construction, this paper deduces influence factors of power flow transfer ratio during the electromagnetic loop failure and puts forward the identifying method of typical electromagnetic loop.The influence factors of stability and transmission capacity of multi-level electromagnetic loop is analyzed.Using PSD-BPA simulation software,actual stability and transmission capacity problems of multi-level electromagnetic loop in East China are described.Secondly, common measures to solve stability and transmission capacity problems of multi-level electromagnetic loop are summarized, including the optimization of system operation mode, operation of new equipments, power flow control technology, electromagnetic loop untying, etc.On account of the defects existing in centralized FACTS, distributed FACTS device to control the power flow of multi-level electromagnetic loop is put forward. Principles of electromagnetic loop untying are put forward and an actual electromagnetic loop untying is analyzed in feasibility.Finally, the concept emergency state of multi-level electromagnetic loop is put forward and the limit of emergency and alert state is declared.This paper proposes dynamic partitioning technology which changes grid topology structure to eliminate the emergency problem during ground state or expected faults and puts forward control strategy respectively for a single and a variety of emergency problems.Comparation of dynamic partitioning technology and traditional control measures is analyzed in space and time.At the same time,coordination strategy between them is put forward.