Study Of Voltage Control Technologies In Loop Distribution Systems Using UPFC

Distribution system is the direct link distributing electricity to users in power system whose reliability and operation stability affects the production and life of the great majority of users directly. To ensure the power supply quality, improve voltage satisfaction and reduce line loss, further enhancing the operation standard of distribution network has been a priority. Distributed generation (DG) technologies could solve the shortage of resources, but the installation of DG has changed the topological structure of distribution system. So the voltage regulation in loop distribution systems with DG has higher degree of difficulty and practical significance. FACTS (Flexibility AC Transmission Technology System) technology is the power electronics technology combining with computer technology and modern control technology and power system. And UPFC (United Power Flow Controller) is the most powerful one in FACTS devices and has the powerful multi-function control ability and flexibility. It can give a huge economic benefit to power system.This paper presents a new method about all nodes voltage regulation based on line loss minimization using UPFC in loop distribution systems with DG.Firstly, the power flow and voltage profiles under both the tie breaker open and closed cases have been evaluated. This paper introduces the operational principle of wind generators, establishes its detailed simulation using PSCAD/EMTDC software and analyses the impacts of the DG installation in loop distribution system by digital simulation. Apply Monte Carlo method to represent the influence of DG installation actually. The probability model about wind speed has been built, in which wind speed is the random variable.This paper mainly presents a comprehensive optimal control method about both voltage deviation of all nodes and active power loss in loop distribution systems with DG. For achieving this objective, firstly, this paper deduces the relationship between the active power loss, voltage deviation of load nodes and series compensating voltage by UPFC. Secondly, it designs the membership function of active power loss and voltage deviation respectively and the comprehensive optimal objective function is set up. And the optimal question is solved by global optimal algorithm using Lingo software. Finally, this paper establishes the detailed simulation of distribution system with duplicate supply using PSCAD/EMTDC software to prove the correctness and availability of the method.The simulation results proves that the method present in this paper can balance the power distribution, control all nodes voltage deviation and decrease the active power loss of the loop distribution network with DG effectively. Then the quality of power supply is been improved.