Restoration Analysis Of±660kV Yin-Dong Direct Current Power Transmission System

With new kinds of equipment such as HVDC and FACTS added into the power system, the controllability and transmission ability of power system is increased, meanwhile the dynamic character is more complicated, bringing new challenge to power system analysis area. The requirement of modern society for power supply is higher, once there is a power failure, the result is worse, so reasonable restoration measures must be implemented to recover the normal power supply as fast as possible, and minimum the lost caused by the power failure.Since the complexity of HVDC transmission technology, its startup is always put at the late stage of black start-up of the power grid after the trunk networks has been recovered in order to ensure that the power system is stable. However, quick restoration of HVDC can play an active role on the whole power system restoration, so it is essential to study on the effect of HVDC in units restoration stage, network reconstruction stage and load restoration stage, and such problems as its operation control mode.The restoration of HVDC transmission system after Shandong power grid blackout is studied, and the main work and achievements are as follows:Factors influencing HVDC startup is discussed, including three aspects:AC system at sending end, AC system at receiving end and HVDC power transmission system. The problems include AC system strength, the coordination of climbing speed of units at sending end and HVDC startup, the unit self-excitation, the reliability of HVDC system components, and the choice of control mode during the startup.According to the study contents of this thesis, the simulation software PSCAD/EMTDC is chosen, and the±660kV Yin-Dong HVDC power transmission system is modeled in detail.Three startup modes are simulated, including one pole1.0pu voltage startup, one pole0.8pu voltage startup and one pole0.7pu voltage startup. Three variables are observed, including the reactive power flowing from HVDC system to AC system, converter station AC bus overvoltage, and AC system frequency. The conclusion is that one pole0.7pu voltage startup mode is better for the HVDC startup.According to the voltage and frequency impact of HVDC startup on AC system, the minimum system conditions are estimated. Then for Shandong power grid±660kV Yin-Dong HVDC power transmission system, simulates the startup under four different typical units start-up modes respectively. The results also show that the Huangdao plant is important for HVDC system startup. So the study in this thesis has reference value for actually Yin-Dong HVDC restoration after Shandong power grid blackout.