| Since the 1960s, large-scale blackouts have taken place in many countries. These blackouts seriously affect people's normal life, causing enormous social impacts and economic losses. Even though the blackouts are not probably happened, fundamentally they are inevitable. Therefore, the research on how to restore the power system quickly and effectively after a blackout is of major importance.The process of power system restoration is complicated and involves many technical problems. During the restoration, operations are likely to cause great impact on frequency and voltage. At the initial stage of restoration, the weak network of power system worsen the situation, frequency and voltage maybe exceed the allowable safe range and slow down the restoration process, even lead to the restoration failure. In order to restore the power system rapidly and reduce the blackout losses, the research and simulation analysis on frequency and voltage during restoration must be undertaken.An analytical estimation of power system frequency response during the startup of power plant large auxiliary motors from remote pumped-storage units is proposed. As the soft feedback magnification of governor is far greater than that of the hard feedback, the transfer function model of pumped-storage unit is simplified. The parameters of induction motor are calculated using empirical formula according to its nameplate parameters. The frequency analytical expression of the power system composed of the pumped-storage unit and the auxiliary motors is deduced by the inverse Laplace transformation. The needed parameters are fewer and the computing speed is fast.Taking a black-start scheme of Shandong power grid as an example, the process that Taishan pumped-storage unit #1 starts Shiheng power plant unit #5 is simulated by PSCAD/EMTDC. Firstly, Taishan pumped-storage unit #1 charges the bus and the auxiliary transformer of Shiheng power plant unit #5, and then gradually starts the domestic load of it, finally, the parallel operation should be achieved at an appropriate moment after Shiheng power plant unit #5 launched successfully. During the simulation of the induction motors startup, the transmission line can be charged section by section, or the breakers of it are closed at first, and then charged at one time. In the process, neither switching over-voltage nor resonance over-voltage phenomenon occurred. During starting the largest auxiliary motor of Shiheng power plant unit #5--feed water pump, frequency and voltage are at a safe range. From the parallel operation simulation, it can be found that appropriate load and the minimal frequency difference between both sides of the synchronization node can reduce the impact of parallel operation.The power system restoration process is extremely complicated, and the dispatchers are lack of adequate power system restoration experience. Therefore, the modern power system cries for a black-start auxiliary decision support system which supports the dispatchers to make a decision. In order to ensure the feasibility of restoration scheme, it is necessary to simulate the process of the induction motor startup. Thus in this thesis a program is developed to calculate the extent of the impact on power system during the induction motor startup, which can check the power system frequency and voltage whether in a safe range or not rapidly. And the program can be embedded in the black-start auxiliary decision support system as a separate module.
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