Study On Power Network Dynamic Process And Control Strategy When The Reserve Power Source Automatic Connecting

Modern power system is a complicate non-linear power system, its basic requirement is to run safely and stably. The destruction of system's stability may lead to disastrous accident such as collapse of system and outage in large extent, and bring great loss to society. One important aspect in study on power system's stability is voltage's stability, especially of recent years, the destruction of power system stability is recurrent because of voltage instability or voltage collapse. Therefore, keeping voltage stability of power system is very important to the safety and confidence of power system.The reserve power source automatic connection (RSAC) is a important measure to increase the reliability of power supply, and generally used in power plant, transformer station and distribution network. As power system progresses, load capacity of distribution network continually increases and the reactive power-voltage characteristic of load continually varies, so the destruction of stability of mains voltage may result in failure of the reserve power source automatic connecting, even lead the network which supplies the reserve power source to collapse with the fault network. Therefore it is very important to analyze power network dynamic process and study control strategies to ensure system stability when the reserve power source automatically connects.The dynamic characteristic of system elements has a great importance on voltage stability when power system suffers different disturbances. This dissertation sets up the mathematical model of network on the basis of analyzing different kinds of elements'reactive power to voltage characteristic, then simulates and analyzes the network dynamic process when the reserve power source automatically connects and proposes corresponding control measures. The following contents are studied primarily:â‘ The connection mode of the reserve power, the basic requirement, the connection diagram and operating principle of the reserve power source automatic connection are analyzed. Especially the principle that the reserve power source automatic connecting fails because of the destruction of voltage stability when two substations are the reserve power source for each other is analyzed.â‘¡The factors that influence the network dynamic process when the reserve power source automatically connects are analyzed, such as the reactive power to voltage characteristic of the synchronous generator, the asynchronous motor and the reactive power compensation device, the starting characteristic and feedback current of the asynchronous motor, the connecting time and capacity of the reserve power source.â‘¢The mathematical model of network is set up by software of MATLAB, kinds of disturbance is given, and the time domain simulation of the dynamic process when the reserve power source automatically connects is processed under each disturbance.â‘£The simulation figures are analyzed, the factors that influence the network dynamic process when the reserve power source connects are found out. Some strategies to ensure the stability of system voltage and the success of connecting the reserve power source are also proposed. The simulation proves that load shedding before connecting the reserve power source is effective measure to ensure the success.