tailieunhanh - Báo cáo "Application of power electronic components to control parameters and switching of compensation devices on power networks "

In practice, consumption devices are not only resistive but also reactive and this reactance varies with time. Therefore, grid voltage is not stable and coefficients always change in spite of using Automatic Reactive Power Regulator. To regulate voltage and cosφ in an expected range, it is necessary to change the parameters of regulators as the loads change. | VNU Journal of Science Mathematics - Physics 25 2009 77-82 Application of power electronic components to control parameters and switching of compensation devices on power networks Pham Van I liepL _ Pham Van Hoa2 Nguyen Quang Viet3 1 2Electric Power University 235 Hoang Quoc Viet street Hanoi Vietnam 3Sience and Technology Dept Electricity of Vietnam 30 Ly Thai To Street Hanoi Vietnam Received 19 June 2009 received in revised form 26 July 2009 Abstract. In practice consumption devices are not only resistive but also reactive and this reactance varies with time. Therefore grid voltage is not stable and coefficients always change in spite of using Automatic Reactive Power Regulator. To regulate voltage and costp in an expected range it is necessary to change the parameters of regulators as the loads change. Determining regulated threshold and time of switching and changing parameters of regulators are controlled by microprocessor and power electronic components. Microprocessor provides a flexible energy control and a high automation ability to ensure a high reliability and stability of the system. This paper presents how to determine the flexible regulated threshold to ensure the quality of supply energy. 1. Introduction The power network configuration is shown in Figure 1. The source of supply to the network is the three-phase three-winding power transformer 500 220 110kV or the high-voltage busbar of the power plant supplies power to loads through primary distribution lines configured as open ring or radial network whose voltage should be stepped down to 35kV 22kV 10kV or 6kV. If the voltage rated at 35kV there should be 35kV distribution lines supply power straight to the facilities and stepped down to 22kV 10kV or 6kV by local step-down transformers. From the 22kV 10kV or 6kV primary open ring or radial distribution lines are connected 1-3 . To supply low-voltage loads distribution transformers which stepped voltage down again to 380 220V are connected to these .