Showing papers in "Ieej Transactions on Power and Energy in 1999"

Daily Peak Load Forecasting by Structured Representation on Genetic Algorithms for Function Fitting

Abstract: Recently, the independent power producers (IPPs) and the distributed power generations (DGs) are increase on by the electric power system with the power system deregulation. And the power system becomes more complicated. It is necessary to carry out the electric power demand forecasting in order to the power system is operated for the high economical and the high-efficient. For the improvement of electric power demand forecasting, many methods, such as the methods using fuzzy theory, neural network and SDP data, are proposed. In this paper, we proposed the method using STROGANOFF (STructured Re-presentation on Genetic Algorithms for Non-linear Function Fitting) that approximate the value of predictive to the future data by the past data is obtained. Also, the weather condition was considered for the forecasting that is improvement, and the daily peak load forecasting in next day on Chubu district in Japan was carried out, and the effectiveness of proposed method was examined.

A Particle Swarm Optimization for Reactive Power and Voltage Control Considering Voltage Security Assessment

Abstract: Summary form only given, as follows. This paper presents a particle swarm optimization (PSO) for reactive power and voltage control (volt/VAr control: VVC) considering voltage security assessment (VSA). VVC can be formulated as a mixed-integer nonlinear optimization problem (MINLP). The proposed method expands the original PSO to handle a MINLP and determines an online VVC strategy with continuous and discrete control variables such as automatic voltage regulator (AVR) operating values of generators, tap positions of on-load tap changer (OLTC) of transformers, and the number of reactive power compensation equipment. The method considers voltage security using a continuation power now and a contingency analysis technique. The feasibility of the proposed method is demonstrated and compared with reactive tabu search (RTS) and the enumeration method on practical power system models with promising results.

A Method for Automatic Tuning of PSS under Restriction of Robustness

Abstract: A method for PSS parameter tuning under restriction of robustness is proposed. In the design procedure, the proposed method uses a low-order linearized model which reprepsents dominant dynamics of the power system. The ignored higher order modes and pertuabation of the low frequency modes are considered as multiplicative perturbations. The controller with high performance and high robustness can be derived by solving a nonlinear optimization problem. Because of the non-convexity of the optimization problem, gradient methods are not suitable for solving the problem. For this reason, the present paper proposes utilization of genetic algorithm (GA) for solving the nonlinear programming problem. The present paper makes it clear through digital simulations using a simple three-machine power system model that the designed controller is effective for damping interarea modes and achieves higher robustness against change of load flow condition than the well tuned conventional controller.

Power System Stabilization with TCSC Based on H∞ Theory

Abstract: Power System Stabilization with TCSC Based on H,,. Theory Lin Su, Student, Tsutomu Oyama,Member, (Yokohama National University) Power system load change and transmition line change occur frequently. System state change in any form is no doubt the major issue in powersystem stabilization. Controllor design of thyristor controlled series capacitor (TCSC) can be formulated as a robust control problem. In this paper, a design approach of TCSC controller is formulated. The approach is based on detail analysis of dynamic characters and practical requirements(stability margin, sensitivity, disturbance attenuation etc.) of power system. Make use of mixed-sensitivity method of H. control theory, a practical controller design is proposed. A design method for weighting functions (W1, W2-1, W3-1) is developed. It consists of design foundation and design steps. An effective TCSC controller is presented. With this designed controller, the power system can be stabilized in larger state fluctuation. Comparing with PID controller, this controller has stronger robust stability and disturbanceattenuation. Simulation results show that the proposed design approach is correct and effective.

Development of a Combined Cycle Plant Model for Power System Dynamic Simulation Studies

Abstract: A combined cycle plant model for pourer system dynamic simulation studies has been developed. The major results of the research are as follows: (1) Scope of the model: The unit plant in the large-capacity power station, which consists of the generator, the gas turbine and the steam turbine, is modeled. The unit plant is assumed to be operated in normal high output power (at least 60% of rated power). In the model, behavior of the output power, exhaust gas temperature, the fuel flow rate, and the air flow rate of the gas turbine, as well as the output power of the steam turbine are represented. (2) Accuracy of the model: The results obtained by applying the developed model to dynamic simulations of an actual plant reveal that the model is in reasonable agreement with the static and dynamic behavior of the plant. (3) Basic behavior of the plant under powersystem disturbances: Using the developed model, the basic behavior of the plant dynamics under power system disturbances such as system frequency change is demonstrated.

Derivation of phase-domain model of an induction generator in terms of instantaneous values

Abstract: It is a common practice that the synchronous machines, induction machines and other rotating machines are modeled in dqO reference frame. However, the external network (transmission lines, etc) is mostly modeled in the phase-domain reference frame. Therefore, if a rotating machine can be modeled in phase-domain reference frame, we can construct the electric network model without reference frame transformation. In this paper, we derive the phase-domain model of an induction generator in terms of instantaneous values, and its validity is analyzed based on numerical simulations.

Power System Damping Enhancement using Unified Power Flow Controller (UPFC)

Abstract: The Unified Power Flow Controller (UPFC) can inject voltage with controllable magnitude and phase angle in series with a transmission line. It can also generate or absorb controllable reactive power. UPFC is expected to be able to damp power system oscillations more effectively than power electronics devices such as SVG and TCSC. In this paper, a control system design of a UPFC for power system damping enhancement based on the eigenvalue control method is proposed. It is made clear that the best design method for the power system damping enhancement is to determine steady-state values of the UPFC control variables and the control parameters of the UPFC such as gains and time constants simultaneously, because the controllability of UPFC depends on the steady-state values of UPFC and the power flow condition. The effectiveness of the proposed control system taking into account UPFC inverter ratings is verified by digital time simulation. Furthermore the effects of the input signals to the UPFC controller on small-signal stability and transient stability enhancement are studied, and it is made clear that UPFC controllers using global information are more effective for power system damping enhancement than those using local information because global information has stronger observability for power system oscillations than local information. © 2000 Scripta Technica, Electr Eng Jpn, 133(3): 35–47, 2000

Proper Configuration of the Charging Station for Electric Vehicle by Weighted Voronoi Mapping Method

Abstract: Proper Configuration of the Charging Station for Electric Vehicle by Weighted Voronoi Mapping Method Fumiko Koyanagi, Member and Yoshihisa Uriu, Member (Seikei University) It is no doubt that an electric vehicle(EV) is going to be a main stream of the transportation resource for persons in the next century. The influence for EV, on the other hand, should be managed properly in accordance with the penetration revel. This is because that the influence caused by chargers seems to be an important issue for both the technique on the distribution level and the social aspect. For the time being, chargers are situated in the particular places, though appropriate installation is required to construct a convenient and accessible infiastructure for EV users. This is also important for the acceleration of EV penetration. Besides, Voronoi mapping is well known method for the proper configuration of equipment geographically. We apply this method to arrange the chargers of electric vehicle in Tokyo metropolitan region properly. Under sufficient survey both of the gas station's market and the properties of the potential EV customers and geographical conditions, we use a weight table to evaluate these factors appropriately. Accordingly, we present an optimal installation technique for EV chargers using the weighted Voronoi mapping method. We also show the prospected shortest distance among the charges in case of 100 chargers situated in Tokyo area. Furthermore, we present a practical example for the proper configuration of chargers for EV in 2010.