Minimum transmission power loss in multi-terminal HVDC systems: A general methodology for radial and mesh networks

Abstract

The significant increase of high-power renewable energy sources (e.g., off-shore wind energy systems) in the power networks, has introduced Multi-Terminal High-Voltage DC (MTDC) grids as a prominent approach for transmitting power with high reliability, security, and efficiency. Nonetheless, MTDC systems introduce several challenges pertinent to operation. This paper investigates optimal power flow in MTDC networks to minimize the transmission power loss via DC voltage control, which is an essential approach for the MTDC network operation to maintain the transmission balance and grid stability. In this paper, a generalized approach for minimum transmission power loss in radial and mesh MTDC networks is presented. Voltage droop control is employed in the radial network, with droop characteristics tuned for optimal power flow, which is supported by an optimization approach. Radial MTDC networks with either a common interconnection node or a common interconnection line are considered. While for the mesh network and due to the difficulty of adjusting the droop gains, an optimization algorithm is merely devised for optimal power flow. A modified CIGRE B4 network is employed in this paper to investigate the presented concept considering several scenarios. Simulation results using the Matlab platform are shown to validate the paper's contribution.