Masahiko Amano

Combining direct and inverse factors for solving sparse network equations in parallel

A new parallel algorithm for solving the forward and back substitution part of the solution of sparse network equations for power systems is proposed. The approach assumes that the network equations are solved by LDU factorization and sparse vector techniques. The parallelization approach is based on the factorization path tree and its main feature is the switching from direct factor to inverse factors to best exploit the parallelism during the solution. The algorithm can be easily mapped on a multiprocessor architecture that exhibits both global and local memories. An illustrative example and validation results showing the effectiveness of the algorithm are also presented. >

Advanced operation guidance system for 500 kV substation

Abstract An advanced expert system for operation guidance in a 500 kV substitution is presented. The system performance is significantly improved reflecting experience in developing the previous system. When a fault or trouble occurs in the substation, real-time interence from on-line information is executed, and guidance of the whole restoration process is offered on the operators request. Histories of measured values are also presented using data from the equipment diagnosis system. Faults and troubles are identified by inference using detailed input informaton and knowledge on all equipment, relays, and situations. Frames and rules described in the knowledge base can be maintained easily by end-users with a knowledge-base maintenance utility. The system installed in a 500 kV switching station has been in actual use since February 1991 in good condition.

Stabilization of a large‐capacity, long‐distance transmission system by an adjustable‐speed flywheel generator

An adjustable-speed flywheel generator (FWG) can control both active power and reactive power rapidly. We have studied the effect of FWG installation on a large- capacity, long-distance transmission system, especially when the system includes loops. In this paper, we describe the selection of FWG location, the selection of stabilizing control input signal, and the required quantities of FWG. FWG location is selected by a PQ-sensitivity method, calculation of which is simple and permits easy understanding of the effect of both FWGs active and reactive power. As a stabilizing control input signal, we use bus voltage frequency instead of power flow because the flow changes stepwise by opening three-phase single-circuit. Additionally, we clarify the FWG quantities that must be designed, such as FWGs active power and reactive power. We considered FWGs slip to determine the quantity because the capacity of the exciter depends on slip.