Design of Wide Area Controllers for Synchronous Generators

Inter-area oscillations (IAO) affect power system stability and power transfer capability. In order to damp out these oscillations, damping controllers such as power system stabilizers and other such controllers are used. However, conventional controllers rely on local signals of the device on which they are mounted in order to provide control action. These local signal based controllers may not be effective in damping out such oscillations. Therefore, wide area controllers were proposed. This has been made possible due to the research and development that has taken place in the area of wide area measurement systems (WAMS).These controllers, which utilise remote signals, have the necessary observability of the inter-area modes in order to dampen out those modes effectively. The use of remote signals, however, introduces non-negligible time delays. This may lead to getting undesirable and even counter-productive effects from the controller. Therefore, during the design of wide area controllers, care must be taken in order to properly compensate for time delays. In this paper, the design process of a wide area controller for synchronous generator is presented. The wide area controller designed is used in a two area, four machine power system and it’s effectiveness in damping out IAO is demonstrated. The effect of time delays on the controller performance is explored. Additional compensation for time delay effects are discussed. Eigenvalue analysis is carried out and time-domain simulations are used to validate the eigen-inferences.