| In recent years, a lot of hydroelectric station built. with the power systeminterconnection, the number of cases of low frequency oscillation between thehydropower plant and the power grid are increasing. At present, a lot of research workis based on power system low frequency oscillation caused by the hydro turbine andgovernor system oscillation, which can not well explain the actual system of hydroturbine and governor system low frequency oscillation caused by network side griddisturbance. Therefore, research on low-frequency oscillation between turbine speedgovernor and power grid caused by network side disturbance is practical significance.Through the research of hydro turbine and governor system, and analyzed the theamplitude frequency characteristicsof hydraulic turbine of PI control system andturbine system model of PID control system of three kinds feedback: guide vanes,relay, power, found that when grid power disturbance is close to the naturalfrequency of the system, may cause the mechanical power forced resonance.On the turbine PI control system and PID control system, turbine mechanicaldamping torque coefficient were deduced and discussed, analyzed effects of themechanical damping torque coefficient on power system damping, found hydroturbine and governor system may provide negative damping torque to the system,causes the system to appear weak damping state. When the network side is disturbed,may lead to the occurrence low frequency oscillation of forced resonance forms onhydro turbine and Governor System.Based on PI model and PID model of hydraulic turbine speed control system, therelay time constant, the four hydraulic turbine regulating system typical linkparameters of unit inertia time constant, damping coefficient, water hammer timeconstants are discussed, analysis the effect of various parameters on the lowfrequency oscillation damping ratio and oscillation frequency, study the mechanicalpower under the network side disturbance of different parameters properties.According to PI speed control of water turbines and turbine PID controlsystem,we design the GPSS correspondingly. Through the analysis the systemdamping ratio and frequency of the additional GPSS controller, found GPSS enhancesthe system damping. Simulation results show that, GPSS could effectively inhibit theoscillation amplitude of hydraulic turbine regulating system caused by network side grid disturbance, and for the stable operation of electric power system is practicalsignificance. |
PDF Full Text Request