Collaborative Optimization Allocation of Grid-Forming and Grid-Following Reactive Power Resources Considering Auxiliary Equipment Services

The large-scale integration of high-penetration distributed photovoltaic systems into distribution networks can result in significant grid voltage fluctuations within a short period. However, centralized regulation instructions for passive/reactive compensation, by themselves, are insufficient for effectively suppressing these fluctuations. Thus, this study used the grid-forming and grid-following control characteristics of modern power electronic inverters to propose an optimal allocation strategy for reactive power compensation equipment. This strategy aimed to address the insufficient proactive support capacity in the reactive power equipment used to suppress short-time grid voltage fluctuations. After establishing uncertain operation scenarios for the distribution network, we analyzed the respective multi-timescale behavioral characteristics of traditional, grid-forming, and grid-following reactive power compensation devices. The primary and auxiliary objectives were to minimize the investment cost of the special equipment and voltage deviation of the entire network, respectively. To achieve these objectives, we established a collaborative optimal allocation model for grid-forming and grid-following reactive power equipment. A multi-timescale cooperative allocation strategy was proposed to decompose the total reactive power demand curves at the equipment installation nodes into reactive power curves for different response levels and then collaboratively allocate the multiple devices. A comparative analysis of the three schemes in IEEE 33-node and 69-node systems shows that the proposed strategy guarantees lower overall network voltages while reducing the cost by at least 20% compared to those of other schemes.