| Pump-storage unit plays an important role on safe and stable operation of electric power system, as it can reduce peak, fill valley, modulate frequency and phase. Considering that pump-storage unit has more operational conditions and changes more intricately, so it is important to study its machine-network stability.The single machine infinite system model of Xiangshuijian pump-storage unit is established considering AVR. The responses under typical small and big disturbance conditions are compared and analyzed. The automatic voltage regulation(AVR) can improve the static and transient stability of system, but it decreases damping at the same time, so the probability of low frequency oscillation is increased. To solve this this problem, one of the most effective measurements is power system stabilizer(PSS).The traditional PSS with electric power as single input signal has serious reactive power antiregulation problem, which is harmful to the safe and stable operation of power system. So the PSS based on PSS2A model of IEEE is adopted to efficiently restraint the phenomenon, which has accelerating power as its input signals and considers the mechanical power. It can restraint the reactive power antiregulation problem under both operation conditions and during the condition conversion.Pump-storage unit can work both at generating and pumping conditions, more complicated than traditional hydroelectric generators, and the parameters have an important impact on its performance, so it is essential to study the parameters calculating method of PSS used on pump-storage unit. The single optimal point method and two optimal points method are used to calculate the parameters. According to the running characteristic of pump-storage, power directional element is added to conventional PSS to constitute a power directional PSS, so it can provide good damping and restraint the low frequency oscillation under both operation conditions. The system responses are simulated respectively in generation and pumping conditions, as well as the conversion progress of working conditions and the results before and after installing PSS are compared, it proves that the PSS can provide the damping for pump-storage unit and the calculating method is valid.To validate the simulation results, the single machine infinite system time-stepping finite element method model based on S-function is established. The time-stepping finite element method can consider the impact of nonlinear factors, including field saturation and distortion, and reflect the running condition factually, improving the accuracy of simulation. In order to research the effect of excitation system on the machine-network stability, AVR and PSS are added to the model of single machine infinite system. The small and big disturbances are calculated to compare and analyze the system stability and the effect of excitation regulating system on the machine-network operating characteristic. It provides reference for the research on the machine-network stability of large synchronous machine.Three-phase no-load short-circuit test of10KW6salient-poles reversed machine is carried out, the measured waveform and simulation results are in great agreement, verifies the efficiency of the method. |
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