H. Kuwabara

A new algorithm for service restoration in distribution systems

This paper proposes a new algorithm to quickly. restore the deenergized loads in a distribution system by using the sectionalizing switches. The computational burden and the solution accuracy of the algorithm is improved by using the concept of the dual effective gradient method. Test results on practical system are given to demonstrate that the algorithm can be used in actual, large scale urban distribution system applications.

An efficient algorithm for load balancing of transformers and feeders by switch operation in large scale distribution systems

A systematic and practical algorithm for load balancing of transformers and feeders by automatic sectionalizing of switch operation in large-scale distribution systems of the radial type is discussed. The algorithm is developed by extending an approximation for load transfer of the desired two transformers. The algorithm is applicable to operations not only in the normal state, but also in the scheduled and failure outage states. Computational experience on a real large-scale system has indicated that the algorithm is valid and effective for practical operations. >

Outage State Optimal Load Allocation by Automatic Sectionalizing Switches Operation in Distribution Systems

This paper presents a systematic and practical algorithm for load transfer by automatic sectionalizing switch operation in distribution systems at a fault occurrence subject to the transformer-capacity constraints and the line-capacity constraints on condition that all the section loads are estimated. The algorithm is developed by introducing the concept of subset sum problem and network structure. Computer experience with a real system indicates that the algorithm proposed here is valid and effective for practical operations.

Voltage crop constrained restoration of supply by switch operation in distribution systems

An algorithm is presented for power system load transfer by remotely-controllable switch operations in distribution systems when a fault occurs. In view of practical use, the authors consider both the current capacity and voltage-drop constraints of this load transfer algorithm. Taking these constraints into consideration, the loads in an out-of-service area are transferred to the transformers in an adjacent area. Since it is possible to reduce the out-of-service area monotonically by switch operation, the algorithm proposed is of practical importance. The algorithm is tested for large-scale real distribution system. The numerical results indicate that the algorithm is valid. >

Multi-year and multi-state distribution systems expansion planning by multi-stage branch exchange

This paper proposes an algorithm for solving a problem of multi-year distribution systems expansion planning in which severe fault cases (multi-stage) are taken into consideration. In the algorithm, the multistage branch exchange algorithm is applied to make the solution accurate, and the decomposition co-ordination method is introduced to make the algorithm efficient. An N-years distribution planning problem is decomposed into N single-year planning problems each of which is decomposed into several planning problems to find a feasible radial feeder configuration according to predetermined severe fault cases. So as to co-ordinate these decomposed problems, so-called forward/backward-path procedure is applied. The validity and accuracy of the proposed algorithm are demonstrated by several numerical examples through comparing the calculation result with the ones by conventional methods.

Totally automated switching operation in distribution system

Several algorithms and methods that tend to be overlooked but are important for the realization of an automatic and systematic switching operation in a distribution system are proposed. To explain the importance of these algorithms and methods, the concept of an operating state is introduced and the correlation of different purpose switching operations is illustrated. Each proposed algorithm or method is proved to be practical by real scale simulation or a field test. >