Abstract
This paper determines the minimum short circuit ratio (SCR) requirement for a modular multilevel converter based high-voltage direct current (MMC-HVDC) transmission systems. Firstly, a simplified model of MMC is introduced; the MMC is represented by its AC and DC side equivalent circuit. Next, by linearizing the MMC subsystem and the DC network subsystem, the deduction of the small-signal models of MMC subsystem, the small-signal model of the DC network and MMC-HVDC are carried out successively. Thirdly, the procedure for determining the minimum SCR requirement of MMC-HVDC is described. Finally, case studies are performed on a two-terminal MMC-HVDC system under four typical control schemes. The results show that the restraint factors for the rectifier MMC is predominantly the voltage safety limit constraint, and the restraint factors for the inverter MMC are mainly the phase locked loop (PLL) or the outer reactive power controller. It is suggested that the minimum SCR requirement for the sending and the receiving systems should be 2.0 and 1.5 in the planning stage.
Highlights
The modular multilevel converter based high-voltage direct current (MMC-HVDC)system has drawn significant attention from both the industry and academia
The validation is performed based on Control Scheme 1, the minimum short circuit ratio (SCR) was studied on the assumption that the AC system impedance angle was 80°
The validation is performed based on Control Scheme 1, the minimum SCR was studied on the assumption that the AC system impedance angle was 80◦
Summary
The modular multilevel converter based high-voltage direct current (MMC-HVDC)system has drawn significant attention from both the industry and academia. As a new breed of voltage-sourced converter (VSC), MMC outperformed the Line Commutated Converter (LCC) thanks to the decoupled control of active and reactive powers, the low harmonic voltages, the flexible scalability and the elimination of commutation failure [1,2,3,4]. MMC-HVDC has been widely used in transmission and distribution applications, such as wind farm connection, multi-terminal operation, and passive network power supply [5,6,7]. One of the most important characteristics for the connected AC system is the short circuit ratio (SCR). For the LCC-HVDC, detailed research has been carried out by CIGRE and IEEE in which the AC system strength is categorized by the SCR [8,9].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
