Yoshihisa Uriu

A strategy of load leveling by charging and discharging time control of electric vehicles

By ZEV regulation of the California government in 1992, not only The United States but also many developing countries are interested in replacing gasoline cars by electric vehicles (EV). The electric utility expects that the electric vehicle improves the difference between the daytime and nighttime of recent demand as a new market of electric power demand. There are some reports that indicate on the danger which generates the new peaks as the electric vehicles spread through the market in charging start hour. As a countermeasure for avoiding this problem, the authors propose that (1) the regional charging time shift method is introduced in the midnight charging time zone, and (2) inverse load flow by the discharge of the contract private use EV is carried out as an energy shift in daytime, in this paper. Therefore, the actual energy consumption of the automobile was investigated, and future demand is predicted by the mathematical consumption modeling. Especially, it shows a strategy of optimum introduction on scheme and rate of electric vehicle for effective energy shift. The authors point out the necessity of market regulation for an electric vehicle.

Modeling power consumption by electric vehicles and its impact on power demand

Electric vehicles are expected to be one of the means to level the difference between the peak time and off-peak time electric loads. From a global point of view, increasing environmental concerns make us recognize the necessity of replacing conventional gasoline cars by electric vehicles. Due to problems with the efficiency and life time of a battery, it will take time before electric vehicles are in general use. Electric vehicles are used only in specialized small fields. Automobile makers are cooperating to invent advanced batteries for use in electric vehicle. Thus, it is timely to develop appropriate infrastructure standards and technologies to make electric vehicles attractive to consumers. In this paper, we investigate the impact of electric vehicle on electricity demands by assuming analytical models of EV consumption. The charging characteristics of a battery, the running performance, and the practical driving distance of each type of car are used in this analysis. According to the scenario analysis, the simulations clearly presented the impact of EV introduction using the practical day load duration curve for the Tokyo cosmopolitan area. The authors conclude that electric vehicles are effective for load leveling under some sort of market regulations. If there is no regulation in the EV market, power shortage will occur on both nighttime and daytime because of the concentration of the nighttime charge and the quick charge.

Single-line-to-ground fault test of a 3-phase superconducting fault current limiting reactor

The current limiting behavior of a 3-phase superconducting fault current limiting reactor (SCFCLR) in a model power system at a single-line-to-ground (SLTG) fault is experimentally confirmed. A small arc gap is attached on one phase of the model transmission line. A single-line-to-ground fault is activated. The behavior of the grounding current and the arc is observed. It is shown that: (1) the fault current is limited to a very small value by the large zero-phase-sequence reactance of the SCFCLR, and the self-extinction of the fault arc is observed; (2) the power flow is not disturbed by a SLTG fault at all, and no power system disturbances are observed; and (3) the windings do not quench for a SLTG fault. A supplementary experiment for a two-phase short circuit fault was also carried out. >

Equivalent circuit and leakage reactances of superconducting 3-phase fault current limiter

The authors have been studying a novel type of superconducting fault current limiting reactor (SCFCLR). The SCFCLR is a reactor which has three superconducting windings with the same numbers of turns wound on a single iron core. An equivalent circuit is proposed for the SCFCLR. Using this equivalent circuit, the leakage reactances of the SCFCLR were calculated, and they agree well with the experimental data. Ground fault tests in a model power system were carried out. When the SCFCLR was inserted in the model transmission line, a ground fault was not observed.<<ETX>>

Development of a dynamical model for customer’s gas turbine generator in industrial power systems

This paper presents a tool, which is implemented on the MATLAB/Simulink environment realizing a user friendly GUI system with object oriented configuration, to analyze the dynamical behavior of industrial electrical power system with a customerpsilas gas turbine power plant. A model consisting of a gas turbine system including the steam flow, a synchronous generator with mechanical and electrical system and an electrical power network with electric circuits is developed. The complicated structure of industrial gas turbine which supplies much steam as well as the mechanical torque for generator is represented clearly with the detailed governor system, synchronous generator and electric network models. Consistent links among subsystems are realized by the function of Simulink. Static and dynamic characteristics of the developed model are presented as well as a brief summary of the developed analysis tool for industrial power systems.

Generator excitation control using a parameter space design method

Recently, the trend of control engineering changes from classical control theory to modern control theory, and also analogue to digital with times. But, even now parameter adjustment in generator excitation control has been often carried out by the classical loop-shaping method using a Bode diagram. Modern control theory has seldom been used in practice due to the facts that the experience of using such design methods is insufficient and there are no introduction results in actual design situations. However, the classical loop-shaping method has some drawbacks, e.g., sensitivity adjustment procedure by a Bode diagram is complicated and cumbersome. In this paper we employ a loop-shaping method using Hinfin norm constraints, which is achieved via a parameter space approach accomplished by symbolic method called quantifier elimination (QE) and apply it to design PI control type AVR of the excitation control. The method allows us to determine appropriate parameter values of PI controller for visually in a parameter space. We report some simulation results for the PI control type AVR design and inspect the performance.

The development of a model of the industrial gas turbine generator on the analysis tool for the power system dynamics

Industrial power systems with industrial power generation plant have very complicated structures. In addition, these systems are usually interconnected with utilities, that is, disturbances in the utility network affect the operation and the protection coordination in industrial systems. Therefore, modeling and analysis technique for industrial power systems should become key issues. This paper presents the model of an industrial gas turbine generator developed on the power system analysis tool based on MATLAB/Simulink that we have developed.

Quench of superconducting magnet induced by mechanical disturbance using impact hammer

In an epoxy-impregnated superconducting magnet, triggers of quench are considered to be conductor motion or epoxy cracking which succeed the temperature rise of the conductor induced by friction between conductor and epoxy or conductor and conductor. A more direct method which makes a quench would be hitting the magnet with mechanical hammer. As far as we know, papers which treated this type of quench are very few. So, we have carried out a quench experiment triggered by mechanical impact induced by dropping a weight. We have investigated the relation between magnitude of the mechanical disturbance and the behavior of the superconducting magnet. And also, we have investigated the relation between the impact energy and the structural change of superconducting magnet using an ultrasonic transfer function which we have already proposed as a quench detection method.

Transient stability assessment of industrial power systems with detailed models implementation

This paper presents a brief summary of issues on industrial customers electrical power systems and an approach to analyze the transient behavior of a system with the group of self-generators, substations and many induction motors. Power oscillations and voltage recovery performance after some contingencies are recognized as typical issues on customers systems. The strong nonlinearity caused by the complicated system configuration falls into difficulties of the proper evaluation of the transient state. Power system analysis is an effective countermeasure for these issues, however, there are some problems on the modeling of each component for better assessment of inherent phenomena. In this paper, required models especially for the complicated governor system for the assessment of the dynamical process are discussed. These models are consistently implemented on the MATLAB/Simulink environment with object oriented configuration. Static and dynamic characteristics of the real power system of a petrochemical plant are investigated as an example.

A Dynamical Model for Customer's Gas Turbine Generator in Industrial Power Systems

This paper presents a tool, which is implemented on the MATLAB/Simulink environment realizing a user friendly GUI system with object oriented configuration, to analyze the dynamical behavior of industrial electrical power system with a customerpsilas gas turbine power plant. A model consisting of a gas turbine system including the steam flow, a synchronous generator with mechanical and electrical system and an electrical power network with electric circuits is developed. The complicated structure of industrial gas turbine which supplies much steam as well as the mechanical torque for generator is represented clearly with the detailed governor system, synchronous generator and electric network models. Consistent links among subsystems are realized by the function of Simulink. Static and dynamic characteristics of the developed model are presented as well as a brief summary of the developed analysis tool for industrial power systems.