Study Of The MMC-STATCOM Control System Based On VME Bus

With the development of the power market, demands for quality andreliability of power supply become more and more strict. Therefore,relevant equipments are required to ensure those demands. As an importantreactive-power compensation device in the Flexible AC TransmissionSystem (FACTS), Static Compensator (STATCOM) has superior controlperformance and compensation effect. The multi-level topology has madeit possible to achieve the application of the STATCOM in the powersystem with a high voltage level. At present, the cascaded multi-leveltopology has become a hot area of research due to its prominent merits,such as a relatively small size, easy to be modularized and high reliability,etc. In this dissertation, the MMC-STATCOM has been chosen as the studyobject. The following research has been accomplished.This paper starts with the basic theory of reactive powercompensation. The traditional reactive power compensation equipments,late-model reactive power compensation devices based on powerelectronic inverting technology and multi-level technology has beensummarized, a detailed introduction to MMC-STATCOM has beencomposed. Then, after analyzing the operation mode and principle ofreactive power compensation of a STATCOM, the mathematical model ofa single cell has been established, together with the models in abc staticcoordinate and d-q rotating coordinate. Instantaneous reactive powertheory has been combined in order to analyse the methods of modulatingactive and reactive power.The control technology for AC side and the balance controltechnology for DC side capacitors of MMC-STATCOM have been studied. State-feedback decoupling control has been chosen to be the controlmethod for AC side, while the control strategy based on active voltagevector composition has been chosen for the balance control, combiningwith the hierarchical control method. The uni-polar double frequencyCPS-SPWM has been deduced from the uni-polar double frequencySPWM. Various features of CPS-SPWM have been concluded.The simulation model has been built in the MATLAB/Simulinksoftware. The static and dynamic performances have been tested withsimulation. According to the waveform and the relavant FFT analysis ofthe measured voltage and current, the superior static performance of thestate-feedback decoupling control has been demonstrated. The excellentdynamic performance of the control system has been testified by manuallychanging the reactive current reference and the reactive power of the load.Meanwhile, features of the uni-polar double frequency CPS-SPWMdiscussed before have been certified.According to the mathematical models and simulation resultsobtained before, a MMC-STATCOM experimental system based on VMEbus has been established. Various components of the main circuits havebeen designed and setup. Hardware design and software development ofthe control system based on VME bus have been accomplished. The staticresponse and dynamic response of the experimental system have beentested. In conclusion, the experimental system is able to preciselycompensate the referenced reactive power with superior dynamicperformance.