Research On Power Flow Optimization And Preverntive Control In The Power System With UPFC

As a powerful FACTS device,Unified Power Flow Controller(UPFC)has a variety of control modes.It can flexibly adjust and control the line power flow,impedance and bus voltage,and has received wide attention in recent years.However,when the UPFC is set in the unreasonable control mode and control target,the control effect of the UPFC may bring the hidden security problem to the system.Therefore,in order to make best use of UPFC,tap the existing transmission potential,improve the static safety of the system and realize the safe operation of the system,the power flow optimization and static safety preventive control of UPFC should be studied.Details are as follows:(1)The location of UPFC and the power flow optimization in the power system with UPFC is studied.Because UPFC installation location directly affects the power flow regulation capability of UPFC,this paper presents a simple and effective UPFC location method which is based on the UPFC direct current power injection model,and determines the installation location of the UPFC in the IEEE30 test system.Then,with the goal of improving the economy of the system,a power flow optimization model with UPFC is established,and the particle swarm algorithm is used to solve it.The influence of UPFC on the system loss is analyzed separately.The results demonstrate that both net loss and system operating costs are significantly reduced,and UPFC is helpful to reduce the system loss.(2)This paper brings forward a power flow calculation methed considering UPFC control modes and analyse the effect of UPFC control modes on power system static security.UPFC has four common control modes:power flow control mode,phase angle adusting control mode,voltage regulation control mode and impedance compensation control mode.By establishing the power flow calculation model of each control mode,the influence of UPFC control modes on power flow distribution after N-1 fault occurred is calculated.The results show that UPFC control modes have great impact on system power flow.To some extent,selecting the appropriate control mode will be helpful to the static security.(3)This paper proposes a static security preventive control method of UPFC considering its control modes and studies the power flow optimization considering static security preventive control.By adding static security constriants into the UPFC parameter optimization model and considering UPFC control mode selection,the preventive control method which can effectively improve power system static security is put forward.Then,by integrating the preventive control strategy and powr flow optimization,the model of power flow optimization considering static security preventive control is established.The calculation results present that the optimized system control parameters,UPFC control parameters and UPFC control mode can make the power system more economical and safer.