J. Kubokawa

An optimal deployment of fuel cells in distribution systems by using genetic algorithms

A fuel cell has been expected to be a very energy efficient and clean device and has been technologically matured to a stage of practical use. In consideration of its relatively small generation capacity, a fuel cell may be installed in a distribution network. This paper presents the framework of a method of introducing fuel cells into a radial distribution system. According to this framework, an optimal deployment problem of fuel cells is formulated as a combinatorial optimization problem. Since this problem has nonlinear objective function to be minimized, the optimal solution could be obtains only through an exhaustive search, which is susceptible to combinatorial explosion for large scale systems. Hence, a genetic algorithm (GA) must be an adequate method to obtain a solution within reasonable computation time. Further, several kinds of techniques to improve GA performance have been introduced in this paper. The proposed algorithm has been applied to test distribution systems of 69 and I I1 nodes with successful results.

A solution of maintenance scheduling covering several consecutive years by artificial neural networks

This paper describes a method of solving the maintenance scheduling problem of thermal power station units by making use of artificial neural networks, which can handle inequality constraints effectively. In the problem formulation, different classes of maintenance works and several consecutive years are considered to obtain a more realistic solution. The problem has been mapped on artificial neural networks and solved by a network simulator.<<ETX>>

A solution of generation expansion problem by means of neutral network

The authors present how to solve power system generation expansion planning by artificial neutral networks, especially the Hopfield type network. In the first place, generation expansion planning is formulated as a 0-1 integer programming problem and then mapped onto the modified Hopfield neural network that can handle a large number of inequality constraints. The neural network simulated on a digital computer can solve a fairly large problem of 20 units over 10 periods. Although the network cannot give the optimal solution, the results obtained are quite promising.<<ETX>>

A solution of unit commitment with transmission and voltage constraints by heuristic method and optimal power flow

In this paper, a heuristic algorithm combined with OPF is proposed for short-term unit commitment problem with transmission and voltage constraints. Being a very complicated combinatorial optimization problem, unit commitment is very difficult to solve, especially, for large-scale power system with network constraints. We have proposed a heuristic algorithm based on the average full load cost without network constraints. In this study, we propose a solution of unit commitment problem with network constraints using combination of heuristic algorithm and OPF. The proposed algorithm has been applied to the IEEE 118 test system with 36 generators over a 24-h period. The result shows that the proposed algorithm is capable of obtaining satisfactory schedules without any constraint violation.

Expert system for designing transmission line protection system

This paper presents a powerful expert system (ES) which makes a basic design of an adequate protective relaying system based on the knowledge of skilled protection engineers. Following the basic design, the ES carries out the relay setting and its validation by means of the integrated power flow and fault calculation programs. Furthermore, the ES has a capability of securing coordination among separately set relays. It is very flexible in that it is able to reset the relays according to power system changes. The effectiveness has been demonstrated by using a part of the Chugoku Electric Power Company System.

A study of allocation planning of dispersed electrical and thermal energy systems into distribution networks-optimal operation planning

The authors have so far studied a framework of an optimal placement problem of dispersed type of cogeneration systems and energy storage systems into distribution networks. The framework has included operation planning and installation capacity estimations before deployment planning. However, the procedures of them were very simple and not enough to reflect the actual situations. In this paper, a new framework is presented that includes other thermal energy sources and provides a more practical operation of them. In order to illustrate improved points, some numerical simulations are carried out by using test data.

Development of Optimal Power Flow and Application to Dynamic Economic Load Dispatch

Abstract This paper presents an extension of an Newton OPF program, which has been developed under the sponsorship of EPRI, and its application to on-line dynamic ELD problem. In the first place, the formulation of a fast Newton OPF in both coupled and decoupled versions is described. Then, developed programs in both the versions are applied to example systems including a 344 node system and results are promising. Secondary, a countermeasure is given to improve the convergence characteristics of the decoupled OPF program. Finally, the developed Newton OPF program is integrated into the on-line dynamic ELD of thermal units in order to take into account both generation rate constraints (GRC) and security constraints. That is, the feasible regions taking into account GRC are computed by the method developed by one of the authors and the fast Newton OPF is utilized to generate economic and secure dispatching command. The effectiveness of our approach has been verified by numerical simulations on the IEEE 30 node system.

A study of outage work allocation by means of agent technology

This paper presents an outage work allocation method by means of agent technology, which is used in the planning supporting system for monthly outage work. The agent technology is used for the purpose of minimizing the maximum of the ratio of the power flow of a line to its nominal capacity. Outage works in the agent are optimized using the extended optimal switching power flow (EOSPF). Adjustment of outage works among various agents has been achieved by communicating with each other. The convergence criterion is that no more communication is tenable. In order to confirm the effectiveness of the proposed method, it has been applied to a real power system with successful results.

DEVELOPMENT OF OPTIMAL POWER FLOW AND APPLICATION TO DYNAMIC ECONOMIC LOAD DISPATCH

This paper presents an extension of an Newton OPF program, which has been developed under the sponsorship of EPRI, and its application to on-line dynamic ELD problem. In the first place, the formulation of a fast Newton OPF in both coupled and decoupled versions is described. Then, developed programs in both the versions are applied to example systems including a 344 node system and results are promising. Secondary, a countermeasure is given to improve the convergence characteristics of the decoupled OPF program. Finally, the developed Newton OPF program is integrated into the on-line dynamic ELD of thermal units in order to take into account both generation rate constraints (GRC) and security constraints. That is, the feasible regions taking into account GRC are computed by the method developed by one of the authors and the fast Newton OPF is utilized to generate economic and secure dispatching command. The effectiveness of our approach has been verified by numerical simulations on the IEEE 30 node system.