Research on Coordination and Optimal Configuration of Current Limiting Devices in HVDC Grids

Jun Mei,Pengfei Zhu,Lingxiao Yan,Guangyao Fan,Rui Ge,Bingbing Wang

doi:10.1109/access.2019.2930748

Abstract

This paper proposes a collaborative optimal configuration method of current limiting reactors (CLRs) and fault current limiters (FCLs) in the modular multilevel converter (MMC)-based high voltage direct current (HVDC) grids. The calculation methods of dc line fault currents and bridge arm fault currents considering the collaboration of CLRs and FCLs have high accuracy. The multi-objective optimization configuration model is established, in which the fault current limiting effect, the total inductances of CLRs and the number of FCLs are used as objective functions while the DCCBs current breaking capacity, the converter valves overcurrent protection, the boundary of the dc line protection area, the dynamic performance of the dc system and the converter station outlet dc voltage are used as constraints. In this paper, the multi-objective optimization algorithm is used to solve multi-objective optimal configuration problem for the CLRs and FCLs. Finally, the proposed method is tested with a symmetrical monopole four-terminal MMC-HVDC grid in PSCAD/EMTDC. The simulation results verify that the proposed optimal configuration method can ensure the continuous and reliable operation of the dc grid under dc faults.

Highlights

With the urgent need of modern power grid for high reliability and high quality power supply, efficient utilization of renewable energy and multi-type power conversion
This scheme is faced with two challenges: a) with the development of dc systems in the direction of high-voltage and large-capacity, the development of the high-voltage and large-capacity DCCB is limited by technical backgrounds and capital costs [8], [9]; b) the insulated gate bipolar transistor (IGBT) has a poor overcurrent capability, modular multilevel converter (MMC) will be blocked to protect IGBT as soon as the fault current in the arms of MMC exceeds a current threshold of the converter valve, resulting in unnecessary power interruptions in the healthy dc system, which undoubtedly is contrary to the original intention of using DCCB to isolate faults quickly in the dc grid [10]–[12]
FUNCTIONS As mentioned above, the main objective of this paper is to find the optimal locations of fault current limiting devices to ensure the continuous operation of high voltage direct current (HVDC) grids under dc faults

Summary

INTRODUCTION

With the urgent need of modern power grid for high reliability and high quality power supply, efficient utilization of renewable energy and multi-type power conversion. The main problem is that the low impedance of dc lines leads to the rapid and extensive development of dcside short-circuit fault currents, which seriously threatens the safe and reliable operation of the system [5], [6]. The scheme of installing dc circuit breakers (DCCBs) at both ends of dc lines can isolate fault lines quickly and restore stable operation of other areas without fault, which can ensure the reliability of the system to the greatest extent It is the protection and restoration scheme for dc grids recommended by CIGRE [7]. DC FAULT PROTECTION SEQUENCE At present, there is still a lack of reasonable and effective collaborative optimization configuration method of CLRs and FCLs in HVDC grids. 2R0 where C0 is the value of the submodule capacitance, N is the number of inserted submodules in each bridge arm, L0 is the value of the bridge arm reactor, and R0 is the sum of on-state resistance of N switching devices in normal operation of single-phase bridge arm (including IGBTs and diodes)

FAULT CURRENT CALCULATION METHOD FOR DC LINES

SIMULATION VALIDATIONS AND RESULT ANALYSIS

SIMULATION RESULTS AND DISCUSSION

SIMULATION AND VERIFICATION

CONCLUSION