Showing papers by "Chen-Ching Liu published in 1989"
TL;DR: Two algorithms are presented: one is based on the uniformly distributed load model and the other on the concentrated current (or power) demand model, based on a concept of 'basic' current profiles of feeder sections and a transformation of the optimization problem.
Abstract: Determining open switch positions for the minimum-loss configuration of a radial distribution system is a discrete optimization problem. The authors present a global optimality condition of the problem and two algorithms: one is based on the uniformly distributed load model and the other on the concentrated current (or power) demand model. The derivation of the optimality condition relies on a concept of 'basic' current profiles of feeder sections and a transformation of the optimization problem. In the first algorithm, a closed form of the minimum-loss open point of a feeder pair can be found since the loss function is piecewise-parabolic. The algorithm obtains the optimal solution when the minimum is obtained for every feeder pair. In the second algorithm, a similar procedure is performed by moving open points, one at a time, from an actual switch position to another until no further loss reduction can be achieved. The proposed algorithm can be utilized as an online aid to distribution system operators. >
153 citations
TL;DR: The capabilities of CRAFT are extended by adding two new knowledge bases with rules to determine the status of unsupervised automatic switches and to detect the presence and location of a manual switch with an incorrect status following a fault.
Abstract: The authors discuss the implementation and operation of an expert system in a control center environment. Attention is given to CRAFT (Customer Restoration And Fault Testing), a rule-based expert system which is capable of locating the faulted section of a power transmission line equipped with automatic switches and circuit breakers. In this study, the capabilities of CRAFT are extended by adding two new knowledge bases with rules to determine the status of unsupervised automatic switches and to detect the presence and location of a manual switch with an incorrect status following a fault. An approach involving the appending of a separate expert system computer to the existing SCADA system is developed. Software and hardware interfaces are designed and implemented. The completed implementation is operating online. >
32 citations
01 Jan 1989
TL;DR: The proposed expert system ERP (Enhanced Restoration Planner) is implemented in PROLOG and is able to come up with appropriate switching actions within a few seconds and can be a powerful tool in aiding the distribution system dispatchers in emergency situations.
Abstract: The service restoration planning in distribution systems deals with the determination of necessary switching actions to restore the service of customers affected by an outage. In practice, it has been performed by system dispatchers based on experience. In this paper, an expert system which has the following capabilities is presented: two-phase service restoration considering zone priority and supervised switches, maintenance switching and user-specified zone priority ordering. The proposed expert system ERP (Enhanced Restoration Planner) is implemented in PROLOG and is able to come up with appropriate switching actions within a few seconds. The proposed expert system can be a powerful tool in aiding the distribution system dispatchers in emergency situations.
2 citations