Research On The Nodal Voltage Stability Of Microgrid

In the modern power grid,AC-DC hybrid transmission system is used more andmore widely.When AC system splitting occurs or maintenance, there would be IslandedSystem at Sending Terminal of HVDC Power Transmission.The grid structure of IslandedSystem at Sending Terminal of HVDC Power Transmission is frail and maintain afrequency stability of the weak ability. If control measures improper,it would most likelyto occur blackouts in large area.Islanded System and the main power grid rely solely on theDC transmission line linking, therefore, how to take advantage of power rapidcontrollability of the DC transmission effectively regulate and control Islanded System isone of the important issues need to be resolved.This paper first analyzes research In motion of island system frequency stabilityand frequency control mode.On the basis of the dynamics and frequency control mode ofIslanded System, establish dynamic mathematical model of system to achieve a simulationplatform used to study DC sender the silos frequency control problems in PSCAD. Studyhow DC emergency power control affect dynamic process of frequency characteristics.For frequency control problem of Islanded System at Sending Terminal of HVDCPower Transmission by analyzing the existing frequency control method. Improving theweaknesses in the existing method which is stability control measures trigger judgmentcondition too simple. A frequency segmented control method which could by multi-triggerjudgment conditions control according to the real-time status of the frequency is given.Bysimulating and analyzing Islanded System at Sending Terminal of HVDC PowerTransmission under several different operation modes, verify the effectiveness of themethod.On the basis of frequency segmented control method,further study the factors ofthe frequency variation. A Frequency control strategy with anticipation behaviorconsidering the rate of change of frequency factors is given.Utilizing fuzzy control method, optimize the determine conditions of frequency deviation level values on the strategyconsidering the rate of change of frequency factors. Having achieved the precise offrequency control measures implemented.In the same way, verify the effectiveness of theproposed method by simulation analysis.