Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Electrical Engineering


Robert T.H. Alden


Transient stability analysis, a necessary tool for planning and operating electrical power systems, is most time consuming to use because of its massive computational burden. Therefore, the solution of this problem on multiprocessor systems has attracted a lot of attention and holds the promise of eventual real-time dynamic security assessment.

In this thesis, methods to speedup the computation of power systems transient stability simulations using parallel distributed processing are examined. The approach of the thesis is twofold. Firstly, practical implementation must consider the use of current widely available networked computers in the industry. Secondly, the parallel distributed algorithms to be developed in this thesis must as far as possible retain algorithmic advances that have been made on its serial counterpart because of their many advantages.

Serial transient stability algorithms are studied and all major algorithmic advances are investigated and implemented. State-of-the-art parallel transient stability calculations are reviewed and for each algorithm the parallelism that has been exploited is identified. The choice of parallel processing hardware and software is of major concern to power utilities. These issues are discussed and justifications for using networked workstation are given.

The two approaches mentioned above lead naturally to coarse-grained partitioning of the transient stability problem. A slow coherency network partitioning that divides the network into several coherent areas along naturally occurring weak links is developed in this thesis. Following network partitioning, computational tasks can be distributed to several computers and then executed simultaneously. Solution of large, sparse algebraic linear systems is required in most power system analysis. In transient stability analysis, the solution of the linear transmission network is the major obstacle to real-time simulations. In this thesis, both direct and iterative methods for solving blocked linear algebraic systems associated with the power network are developed and implemented on a cluster of workstations. RPC (Remote Procedure Calls) techniques together with multiprocessing primitives are used for client-server communications. These aspects and techniques are fully discussed in this thesis.

Based on the network partitioning and solution methods developed, a transient stability algorithm is parallelized. The process of parallelization is carefully demonstrated. Both shared memory multiprocessor and RPC based--distributed memory--versions are developed. The corresponding speedup due to these methods are analyzed and discussed. It is shown that techniques developed in this thesis can be applied to production grade transient stability programs.

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