Method for voltage drop compensation in a multi-terminal dc network

The power flow is driven by the voltage drop in the dc network. In long-distance bulk power transmission cases, the voltage drop across the network might be severe with some node voltages susceptible to load variation. To tackle this problem, a voltage drop compensation method is proposed. A component called voltage compensator (VOLTCOM) is integrated inside the network to modify the network topology and thereby reduce the voltage drop and node voltage variation. From a system perspective, the characteristic of the VOLTCOM is designed and the compensation principle is explained. Then a scheme to lay out VOLTCOMs in the network is given with the objective to minimise the power rating of VOLTCOMs needed. The simulation results show that the load is transmitted with less voltage drop. The voltages remain in the stipulated range even when the grid reaches the planned operating status limits. Also, the VOLTCOM auto-regulates its output without communications with converter stations. The techno-economic assessment demonstrates the economy of the method compared to enlarging conductor cross-section. As an alternative to enlarging conductor cross-section, the proposed method provides an innovation worth consideration in network design.