This paper presents the explanation and the application of meta-heuristics in power systems. General optimizations are defined as an iterative solution search algorithm that makes use of simple rules or heuristics to obtain better solutions. In recent years, the research reports of meta-heuristics have been positively made to solve the complicated optimization problems. In this paper, the recent trends on the application of particle swarm optimization method are discussed, which can be applied to the solution of a wide range of optimization problems with both continuous and discrete variables.

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This paper proposes a hybrid method of Deterministic Annealing (DA) and Fuzzy Inference Neural Network (FINN) for electric power system fault detection. It extracts features of input data with two-staged precondition of Fast Fourier Transform (FFT) and DA. FFT is useful for extracting the features of fault currents while DA plays a key role to classify input data into clusters in a sense of global classification. FINN is a more accurate estimation model than the conventional artificial neural networks (ANNs). The proposed method is successfully applied to data obtained by the Tokyo Electric Power Company (TEPCO) power simulator.

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In this paper, a new efficient method is proposed for power flow calculation in radial distribution systems. The distribution busines is changing the need to plan and respond to technical change, growth in distributed generation and deregulated power markets. Thus, it is important to improve fundamental analytical tools in distribution systems. This paper proposes a new method for the power flow calculation in distribution systems. The Newton-Raphson method does not work in some distribution systems. As a result, DistFlow that focuses on the network topology was developed to overcome the problem. However, there is still room for improvement in terms of computational efficiency. In this paper, a method is proposed to improve the efficiency in creating the Jacobian.

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This paper aims to develop a novel methodology to decompose MCP (market clearing price) in a single price auction market with AC transmission network. Specifically, we first formulate the auction market as a nonlinear optimization problem, and then propose an algorithm to decompose MCP into various factors, such as bidding curves, generations, transmission congestion, voltage limitations and other constraints. Several numerical simulations have been used to demonstrate the effectiveness of our approach.

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This paper proposes the wind collector for the wind power generation. By this wind collector, the wind which passed the wind generator system is accelerated. As the result, it is possible that the wind generator system gets the rated wind velocity in low wind. The effectiveness of proposed wind collector is examined using the computer simulation. The examination was made the following three points.
·By computer simulation, the optimal angle of wind collector was computed.
·Using the wind collector confirmed that accelerated wind velocity by computer simulation.
·The effectiveness of the wind collector was confirmed by field trial.

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Electromagnetic waves have come to be used for measuring partial discharge, which is indispensable for predictive maintenance for GIS. The UHF method, using the frequency band of 300MHz to 3GHz with generally less noise is one of the advanced technologies of insulation diagnosis of GIS. There are three categories of electromagnetic wave propagating in coaxial cylindrical structure like GIS, namely, TEM, TE, and TM modes. In the frequency region above the cut-off frequencies of the TE or TM mode, the resonance characteristics of each mode that depend on the length of the waveguide and the cut-off frequency are appeared. When the coaxial waveguide has one or two spacers inside itself, the output characteristics of UHF sensor at the resonant frequencies are different by the number, the layout and the thickness of spacers. This paper describes the effect of spacers on the output characteristics of UHF sensor in non-reflection coaxial waveguide at the resonant frequencies of TE11 mode.

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Flow electrification phenomenon is one of the most important problems for electrical insulation of oil immersed transformers. In order to clarify the process of the flow electrification phenomenon in detail, the behavior of the electric field and the charge in the oil gaps was investigated by using the multipoint electric field measurement systems based on the Kerr effect. So far, it was thought that the electric field in the oil gap was distributed uniformly under DC stress. It was, however, proved that the field distribution under DC stress wasn't uniform through the multipoint measurement of the field distribution. Further, it was supposed that this field distortion was formed by movement, generation and extinction of the charge in the oil. In this paper, the experimental results and simulations of the electric field distortion phenomenon under DC stress are discussed.

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The electricity price will influence the future growth and mix of generation capacity that will in turn influence the future electricity price, and therefore, it is important to understand how electricity price is formed as well as its short-term and long-term impacts on the economy. This paper describes evaluation of PJM day-ahead market bidding data and comparison of various electricity markets in terms of the market clearing price and volatility. The objective is to find critical factors and mechanisms determining the movements of electricity price. It was found that speculation by a small number of bidders can cause price spikes, that a Nash equilibrium may exist during a delayed response of the electricity price to a decline of the fuel price, and that the hydro generation with storage capability effectively stabilizes the electricity price.

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Distributed generators (DGs) such as fuel cells and solar cells etc. are going to be installed in demand side of distribution systems. The distributed generators can reduce distribution loss by appropriate allocation. However, there are several problems to install DGs such as service restoration of distribution system with DGs and so on. When one bank fault of distribution substation occurs in distribution system, since DGs are simultaneously disconnected from the system, it is not easy to restore isolated load by one bank switching in distribution substation. Therefore, a service restoration method to determine restoration configuration and restoration procedures (switching procedure from normal configuration to restoration configuration) taking into account simultaneous disconnection of DGs is needed. In this paper, the authors propose a computation method to determine the optimal restoration configuration and the restoration procedure considering simultaneous disconnection of DGs by one bank fault of distribution system. In the proposed algorithm, after all of restoration configuration candidates are effectively enumerated under the operational constraints, the optimal configuration to restore the isolated load is selected among enumerated configuration candidates. After determining the optimal restoration configuration, the optimal restoration procedures are obtained by greedy algorithm. Numerical simulations are carried out for a real scale system model with 237 sectionalizing switches (configuration candidates are 2²³⁷) and 21DGs (total output is 5250kW which is 3% of total load) in order to examine the validity of the proposed algorithm.

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In recent years, there is a great deal of interest in distributed generations from viewpoints of environmental problem and energy saving measure. Thus, a lot of distributed generators will be connected to the distribution network in the future. However, increase of distributed generators, which convert natural energy into electric energy, is concerned on their adverse effects on distribution network. Therefore, control of distribution networks using Flexible AC Transmission System (FACTS) devices is considered in order to adjust the voltage profile, and as a result more distributed generations can be installed into the networks.
In this paper, four types of FACTS devices, Static Synchronous Compensator (STATCOM), Static Synchronous Series Compensator (SSSC), Unified Power Flow Controller (UPFC) and self-commutated Back-To-Back converter (BTB), are analyzed by comparison of required minimum capacity of the inverters in a residential distribution network with a large penetration of photovoltaic generations.

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We have developed a new environmentally fitted 24kV cubicle-type gas insulated switchgear (C-GIS) applying our dry air insulation technology and the electromagnetic actuation technology. Firstly, we clarified the relationship between the breakdown field strength at the tip/edge of high-voltage electrode in dry air and the field utilization factor expressing non-uniformity of the insulation gap. Based on the relationship, we designed the most suitable configuration and arrangement of the parts such as high-voltage conductors, disconnecting blades and some mechanical parts in a gas vessel. We succeeded in reducing both the number of insulation barriers and their size, compared with the former product. To reduce them, we produced some sample gaps simulated a practical insulation gap in the C-GIS and investigated its breakdown voltage dependence on the barrier height. Secondly, to apply the electromagnetic actuators for the operation mechanisms of the vacuum circuit breaker, we developed a new coupled analysis method that estimates the movement of a plunger inside the electromagnetic actuator and the electric current flowing through a closing/opening coil. Based on the analysis method, we could reduce both the number of the parts and close/open energy 45% and 80%, respectively, compared with the former spring-charged mechanism.

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The authors newly propose and investigate the carbon-dioxide-recovering SOFC/GT combined power generation systems. In the systems, the fuel gas is at first introduced to the SOFC, and then its exhaust fuel gas is afterburned by carbon dioxide or water vapor added pure oxygen and drives the bottoming gas turbine. The exhaust gas of the gas turbine, which is composed of only carbon dioxide and water vapor, preheats the fuel and the additional gas, and then the carbon dioxide is recovered by only cooling and water condensation. As for the systems utilizing the natural gas, the overall efficiency (HHV) of the carbon dioxide added oxygen combustion type reaches 64.20%, and that of the water vapor added type 64.93%. As for the systems utilizing the coal gas, that of the carbon dioxide added oxygen combustion type is 58.58%, and that of the water vapor added type 60.37%. These values are sufficiently high, indicating that the proposed systems are worth further research and development.

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In order to clarify the instability phenomena of a low current in the vacuum, the optical characteristics of a low current vacuum arc was investigated by using Cu, CuW, CuCr, CuBi, and AgWC electrodes. We measured the spectrum-line intensity distribution against wavelength during arc discharge for each electrode. It was found that for Cu, CuW, CuCr, CuBi and AgWC electrodes, the total amount of the spectrum intensity from 350nm to 950nm wavelength (SI) increases in the order of Cu, CuCr, CuBi, AgWC, and except for CuW the chopping current decrease in the same order.
For each component of every electrode material, the spectrum intensity and its attenuation speed of the neutral vapor at current chopping (Ucn, dUcn/dt) were investigated.
It was found that the attenuation speed at current chopping decreases in the order of Cu, CuW, CuCr, CuBi and AgWC, the chopping current decreases in the same order.
We will inspect the current chopping phenomena by observing the intensity change of the neutral vapor, and discuss relationship of electrode material and the chopping current from a new viewpoint of evaporation ability and the plasma decay speed.

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A Cockcroft-Walton (CW) type high-voltage DC generator is widely used for the electron processing system (EPS) which is applied for industrial purposes, such as radiation modification of polymers, medical product sterilization, and so on. The DC generator composes of the capacitors and diodes connected as cascade, and a step-up transformer.
A new type high-voltage DC generator with RF air-core transformer used as the step-up transformer has been developed. The design concept of this air-core transformer, which is operated on the resonance condition between the inductance of the secondary coil and the stray capacitance of CW circuit, has been shown and the optimum coil structure has been proposed. Adapting the RF air-core transformer to DC300kV 100mA small CW circuit, the excellent performances have been successfully demonstrated. In this new CW circuit, it results in downsizing of the capacitors to operated at the higher frequency than the conventional one, and the approximately 40% reduction of the volume has been shown in the typically DC1MV 100mA generator.

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