Power-Voltage Coupling Characteristic Analysis of Power Grid Integrated with Distributed Energy Resources

The increasing proportion of renewable energy generation resources in a power grid, has resulted in the generation capacity reduction of traditional synchronous units significantly, and in turn the insufficient regulation capability for reactive/voltage control of the power grid. It is particularly a case for the power grid where the power generation is mainly supplied by LCC-HVDC (Line Commutated Converter based High Voltage Direct Current) links. The distributed energy resources (DERs) can be alternative regulation reserves for voltage control of such kind of power grid. In this paper, steady-state voltage-dependent models of DERs i.e., renewable energy, energy storage, and flexible loads are established, and analyses the relation between the power of DERs and the voltage of grid-connected points. Based on these models, the voltage sensitivity matrix of the power grid is modified for power flow calculation. Then, the influence of DERs integration on grid voltage characteristics is analyzed through power flow calculation. Finally, the effects of different DERs and their penetration levels on the voltage regulation capacity of the power grid are verified by simulation.