A Preventive Control Strategy of Embedded VSC HVDC in a Large-Scale Meshed Power System

When VSC HVDC is applied to the meshed power system, if the appropriate operating point is not determined, it is adversely affected to the total power system. To avoid the side effects of HVDC operation, this paper proposes a method to determine the proper operating point of VSC HVDC. Especially, the control of the VSC HVDC can be a burden for the system operator. In order to alleviate this burden, preventive control should be applied to reduce the burden on system operators. The danger of overloading of the AC line is predicted in advance, so that the operating point at which overload does not occur after an accident is determined as the operating point of VSC HVDC. The typical conventional VSC HVDC control methods are constant active/reactive power control and remedial action scheme. In the former case, there is no control after the contingency, which can cause AC overload or overvoltage problems. The latter controls the operating point for system reliability, but it can be a burden for the system operator and can cause problems in the system in case of communication failure. On the other hand, when applying the preventive control, it is possible to determine an operating range in which the AC load and the overvoltage do not occur even after N − 1 contingency in the operating range of VSC HVDC. In addition, in this paper, we proposed an operating point that minimizes the system’s total losses in the area. The proposed control strategy can reduce the burden on the VSC HVDC operation and can also provide economic benefits by reducing losses. This will be one of the VSC HVDC operation plans that can be selected by the system operator in the future.