Study On The Interactions And Coordination Of The Multiple FACTS Controllers In Power System

China Electric Power Grid is being one of the largest power systems in the world, which has the most complex network configuration. With developing the interconnected grid of large scale, the problems of power system, such as security, stability and vulnerability, are being more prominent. The technique of Flexible AC Transmission System (FACTS) appearing to provide an effective mean, which can improve the control of power flow, and enhance the capacity of transmission line.As fast and flexible controllable power-electronic components, FACTS are widely applied to the grid, which provides a new regulative means, but also brings some new problems. How to maintain coordinated operation of the multiple FACTS'controllers is one of key issues.According to the research studied by some academician:there could be interactions between multiple FACTS'controllers in a complicated power systems, which make instability of FACTS'controllers. Therefore, to analyze the determinative factors of the interactions, and to design the coordinated operation of FACTS are necessary. And it's significant to develop further theoretical research and engineering application of FACTS. Focusing on this issue, the paper based upon the work of previous lecturer, include the following parts:In the first part, the physical structure and mathematical models of four typical FACTS devices, i.e., SVC, TCSC, STATCOM and UPFC are introduced. And the dynamic model of a multi-machine power system installed with FACTS is derived. Upon the mathematical model, the transfer function of the power system can be gained by linearization mean. Then, the Gramian index is used to assess the interactions between FACTS'control channels. In the two-area four machine power system, the negative interactions between FACTS'controllers are demonstrated. Moreover, considering different operating conditions, the influences on the interactions caused by system load and electrical parameters are investigated. The effectiveness of Gramian index in analyzing interactions is validated by time-domain simulation method.Then, from the electrical architecture point of view, using the device models provided by power system analysis package-PS AT, the SIMULINK model of the IEEE14-bus power system installed with STATCOM and UPFC is built. On this basis, from two aspects including the static stability and dynamic stability, the interactions between FACTS'controllers are analyzed. By simulation, the conclusion that the proposed installation location of FACTS can reduce the interactions between the controllers is achieved.Usually, FACTS'controllers are designed under SISO condition, there are interactions demonstrated above. To solve this question, the multi-objective optimization using artificial immune algorithm is proposed to optimize the controllers'parameters. Simulation results show that the negative interactions can be reduced, and the dynamic performance of FACTS' controllers is meliorated, by using the optimized controllers'parameters. Meanwhile, the coordinated design of the multiple FACTS'controllers is a feasible scheme, which can improve the operating conditions of power system after interference, and enhance the stability.