Study on Control Strategy Based on Voltage Re-injection STATCOM
With the continuous improvement of the manufacturing level of power electronic elements and the increasing demand of power quality by the people,the static synchronous compensator(STATCOM)based on the voltage re-injection converter has a fast dynamic response speed,does not require filtering devices and outputs low voltage harmonic contents and is suitable for high-voltage and high-power transmission systems.The main circuit re-injection topological structure of the DC voltage re-injection type STATCOM consists of two three-phase full bridges in series and an additional re-injection branch,and the re-injection branch adopts a cascaded H-bridge structure.The zero-crossing interval generated by the re-injection voltage can achieve the zero-voltage on-off of the three-phase full-bridge switch.The construction method of the re-injection branch pulse sequence is designed and an improved cycle logic trigger sequence is proposed.The simulation shows that the re-injection branch can effectively suppress the capacitor voltage unbalance in the re-injection cascaded H-bridge under the specific cyclic trigger pulse.The advantages of the converter in terms of zero-crossing turn-off and harmonic elimination are verified by the simulation platform.The reactive current is taken as a direct control command,a closed-loop control system is set up to verify that the STATCOM can effectively reduce the harmonic content and switching frequency in high-voltage and high-power systems,improve the operation reliability of devices and systems,and is especially suitable for high-voltage and high-power environments.
reactive power compensationSTATCOMvoltage source convertervoltage re-injectionhigh voltage and large capacity
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