Power system dynamic response calculations

Engineers in the power industry, face the problem that, while stability is increasingly a limiting factor in secure system operation, the simulation of system dynamic response is grossly overburdening on present-day digital computing resources. Each individual response case involves the step-by-step numerical solution in the time domain of perhaps thousands of nonlinear differential-algebraic equations, at a cost of up to several thousand dollars. A high premium is thus to be placed on the use of the most efficient and reliable modern calculation techniques. This paper is a critical tutorial-review of the calculation methods used routinely or investigated for use by the industry. It concentrates on solution concepts and computational techniques rather than on the analysis of the numerical methods. Details of system modeling are only emphasized when they affect the choice of solution method. The paper concludes with a view of the state of the art and a prediction of future directions of development.