Ken-ichi Nishiya

A study of transmission planning under a deregulated environment in power system

Under a deregulated environment, power system operators such as utilities have to expand and reinforce the transmission network so that all participants can utilize the network equally and fairly. However, it is difficult for the power system operators to forecast how often the network will be utilized or which bus the users will connect to. Therefore, more uncertain factors exist in the transmission planning problem under a deregulated environment. This paper presents a method for evaluating the maximum power which can be injected to a bus and identifying some transmission lines which result in the bottleneck under the uncertain conditions. This paper also investigates a probabilistic load flow to consider the statistic characteristics of load change and line fault occurrence.

A study on the optimal voltage regulation methods in power distribution systems interconnected with dispersed energy storage and generation systems

This paper deals with optimal voltage regulation methods in power distribution systems including dispersed energy storage and generation (DSG) systems. In order to deliver suitable voltages to as many customers as possible, optimal sending voltages should be decided by the effective operation of voltage regulators at distribution substations. In this paper, optimal voltage regulation methods are presented based on statistical analysis considering the customer voltage conditions and operation characteristics of DSG systems. Optimal operation methods of multiple voltage regulators are also suggested. In addition, the introduction impacts of DSG systems such as optimal location sites and introduction capacity are evaluated.

An allocation of wheeling costs in power systems with FACTS devices

This paper presents an index for evaluating the contribution of flexible AC transmission system (FACTS) devices to relief of network congestion under an open access network environment. Since the proposed index can be obtained for each wheeling which causes the congestion, the cost for controlling FACTS devices can be allocated adequately considering the responsibility for the congestion. The characteristics of the proposed index are investigated using a revised IEEE 14-bus test system in details.

An evaluation of the influence caused by the introduction of IPP considering the uncertainty of supply capability

Recently, utilities have been able to purchase the electric energy supplied from independent power producers (IPP) owing to deregulation in the electric industry. This paper evaluates the influence of IPP uncertainty on the utility and/or customer. In general, the production cost of energy supplied from IPPs is lower than that of a utility, although the IPP energy has more uncertainty compared with the utilities energy. This paper analyzes the effects caused by IPPs from the following three points: (i) By modeling a process of determining purchased power price as a negotiation model, the authors evaluate the influence of its uncertainty on a potentiality to introduce IPPs through variation of the purchased price. (ii) The authors evaluate the difference of power system reliability between a system under the deregulated environment with IPPs and a conventional system without IPPs. It is assumed that the system reliability is determined by minimizing the sum of supply cost and outage cost. (iii) Finally, the authors evaluate how the customers various requirements about reliability influence the introduced amount of IPPs.