Shuhei Fujiwara

Development of Doubly-fed Wind Energy System Model for DG embedded Power System Studies

In this study, we have developed a generalized model of doubly-fed type wind energy system that include a wind turbine with pitch control, inverter-converter control, and start-up control. The usability of the developed model is checked by evaluating the impact of voltage fluctuation, voltage drop on power system under different test conditions. In this regard, some results of comparing the doubly-fed model with other types of wind energy systems, such as conventional induction motor type and DC link type, are discussed.

Development of Fast Simulation Model for Doubly-Fed Wind Generation Systems

Abstract – We propose a fast simulation model of wind generator with a frequency converter, such as a doubly-fed type. The aim of the model is to provide a model that can evaluate an impact of wind generator system (WG) on utility side in both transient and relatively long term normal operation. Through, some simulation software based on root mean square value, for example EUROSTAG, provides a unified method that can handle both short-term and long-term analysis. But it is difficult for RMS based model to handle with a behavior of WG with a frequency converter under system fault condition. So we have developed an instantaneous value based fast simulation model that can handle with both short-term and relatively longer-term analysis.. Keywords : Wind power generation, Fast simulation model, Simplification for converter 1. Introduction The integration of wind generator system (WG) has large influences over a variety of operational conditions. These operational conditions vary from short-term, such as a transient behaviour during a fault, to longer-term, such as power fluctuation under a normal operation. In order to harness WG successfully, the impact of WG must be analyzed in both short and long term. As a result, both short-term and long-term simulation models for WG are required, and it is high burden in view of cost and maintenance. For longer-term analysis, the focus point is mainly active and reactive power swing due to wind fluctuation, and a simulation model based on root mean square value (RMS) is suitable. There are already some RMS based simulation tools that can handle with both long and short term analysis, such as MATLAB. But, in short-term analysis, a simulation model for WG should be represented in detail manner, and a model based on an instantaneous value is appropriate. Because, under a fault condition, WG with FRT(fault ride through) function acts in complex manner, and the behavior during a fault condition could have a large impact over a subsequent longer-term situation. It means that a simulation model for WG based on an instantaneous value is suitable. But it is very time consuming to conduct a long-term analysis with a model based on an instantaneous value. To solve this problem, we have developed and evaluate a fast simulation model for WG based on an instantaneous value that can handle with relatively longer-term analysis. In this study, we first developed a simulation model for WG to conduct both short-term and long-term analysis. Our aim of the model is to evaluate an impact of WG on utility side. The developed model is doubly-fed type. It includes pitch control, frequency conversion, start-up and shut-down function, and FRT(Fault Ride Through) so that we can evaluate WG under a various operational conditions. Then we applied a simplification method to the simulation model so that the model can handle with relatively longer-term analysis. The method of simplifica-tion is to model self-commutated converters in frequency converter as a pair of voltage and current source. The AC side of converter is represented as a voltage source, whereas the DC side of converter is represented as a current source. Through this kind of simplification may be popular in simplifying a self-commutated converters, we do not see any report that evaluates this simplification method under various operational conditions of WG. So, we evaluate this simplification method in this study.

Role of Simulation Technology in Distributed Energy Integration from Japanese Utility Perspective

With a rapid increase of dispersed generation (DG) like wind power etc. in Japan and around the world, there is a growing need for distributed energy integration (DEI) in the power grid as a reliable and a responsible source. In accomplishing this task, a number of underlying technical challenges need to be addressed successfully. In finding solutions to such technical issues, the role of simulation technology is extremely important. In order to appraise the DEI from the Japanese utility perspective, this paper focuses on the simulation studies concerning the modeling aspects of DGs like wind power (WP), etc., validating techniques for the DG systems, as well as the impact of the DGs on protection system or power quality. All these aspects are discussed and described through illustrations.