transferring provided power of wind farms problem when the position of consumers is far from mentioned units where, using. FACTS devices are considered in ...
Dynamic and Stability Improvement of a Wind Farm Connected to Grid Using UPFC M. Tarafdar Hagh, A. Lafzi and A. Roshan Milani Electrical Department, University of Tabriz, Tabriz, Iran
Abstract- Wind power exploitation development to provide Electricity has had more acceleration in recent years in compare with other sources of providing electrical energy in the world. Since, regions with the potential of wind energy are not necessarily close to consumers ,analyzing and modeling of wind farms in order to distribute system load and to study the electrical and mechanical changes of them is important in many aspects and generally ,wind farms which are connected to electricity system by radius and local grids, will face possibility of transferring provided power of wind farms problem when the position of consumers is far from mentioned units where, using FACTS devices are considered in order to keep stability and to create provided Electricity transferring conditions to consumers. In this paper, a wind farm modeling and UPFC using are studied to solve the wind farms power transmition problems. I. INTRODUCTION
Because of electrical grids development, specially wind energy usage and wind farms construction and connecting them to general electricity grid, optimum use of existing grids and dynamic stability increase of them has a special importance. UPFC (unified power flow control) with the ability in unified power controlling is able to control the active and reactive power flowing by the line, independently and can correct the parameters like terminal voltage and load angel using UPFC in a single grids requires exact studies on it’s installation in the grid [1]. Different models for UPFC are introduced in various studies, which one of the ideas is detailed model appliance in which, all switches dynamic is modeled, this method is not suitable for dynamic studies because it requires a long time to be simulated [2]. The other method is using current injection sources for UPFC analysis. This method’s weak point is it’s appliance in a specified frequency and so electrical parts dynamics are omitted [3, 4]. In this paper structure and UPFC functional basics under stable conditions and induction generator model and wind turbine model is mentioned initially and then the effect of UPFC connected to a sample wind farm, in respect wind velocity changes and wind farm distance to grid and power flow are studied.
II. STEADY STATE MODEL OF THE UPFC Unified power flow control (UPFC) is able to control active and reactive power flow the transmition line and bus voltage regulating synchronously. Fig.1 shows UPFC schematic which contains a parallel ac/dc voltage source converter and a series dc/ac voltage source which are connected by a dc capacitor. UPFC is combination of a parallel reactive power compensator (STATCOM) and a series compensator (SSSC). Series converter has the ability to control voltage angel and amplitude that regulate the active and reactive power flow of transmition line by voltage injection. Parallel converter provides the real power required by the series converter, converted between the grids. Dc capacitor provides the possibility of converting the real power between two converters [5]. Stable function of UPFC with two series voltage source converters VB
