A Decentralized Optimal Load Current Sharing Method for Power Line Loss Minimization in MT-HVDC Systems

Abstract

This paper discusses the elimination of DC voltage deviation and the enhancement of load current sharing accuracy in multi-terminal high voltage direct current (MT-HVDC) systems. In order to minimize the power line losses in different parallel network topologies and to insure the stable operation of systems, a decentralized control method based on a modified droop control is presented in this paper. Averaging the DC output voltage and averaging the output current of two neighboring converters are employed to reduce the congestion of the communication network in a control system, and the decentralized control method is implemented. By minimizing the power loss of the cable, the optimal load current sharing proportion is derived in order to achieve rational current sharing among different converters. The validity of the proposed method using a low bandwidth communication (LBC) network for different topologies is verified. The influence of the parameters of the power cable on the control system stability is analyzed in detail. Finally, transient response simulations and experiments are performed to demonstrate the feasibility of the proposed control strategy for a MT-HVDC system.

New Differential Protection Method for Multiterminal HVDC Cable Networks

“…Therefore, an HVDC link can maintain the specified power flow regardless of severe and dangerous electromechanical oscillations present in the network [3][4]. Improvements in DC voltage measurements at different busbars in different substations have been developed and DC power flow control is therefore more precise [5][6].…”

New Differential Protection Method for Multiterminal HVDC Cable Networks

“…For instance, when an imbalance in the AC system (due to any kind of disturbance) is about to occur, the amplitude of the power of the DC line can be changed to counteract and reduce the power oscillations. Therefore, an HVDC link can maintain the specified power flow regardless of severe and dangerous electromechanical oscillations present in the network [3,4]. Improvements in DC voltage measurements at different busbars in different substations have been developed, and DC power flow control is therefore more precise [5,6].…”