Bi-Level Collaborative Voltage Regulation for Distribution Networks with High-Penetration Renewables and Multi-Microgrids Considering Operational Economy

This paper addresses voltage fluctuation issues in distribution networks under high penetration of renewable energy. It proposes a collaborative voltage regulation method for multi-microgrid systems considering operational economy. To mitigate voltage violations and fluctuations caused by intermittent distributed generation such as photovoltaics, this paper develops a bi-level coordinated optimization framework with bidirectional feedback. At the upper level, the distribution network acts as the global regulator, suppressing voltage fluctuations by optimizing the active power output of microgrids while dynamically issuing voltage constraints and power exchange boundaries. At the lower level, each microgrid serves as a local response agent. While complying with the regulation requirements from the upper level, it coordinates its internal distributed resources, including PV, energy storage, and electric vehicles, and optimizes electricity market purchases to minimize its own operating cost. The framework moves beyond traditional one-way command models, achieving bidirectional coordination between global optimization and local autonomy. Simulations based on a modified IEEE 33-bus system show that the proposed method maintains all node voltages within the allowable range, significantly reduces voltage fluctuations, and lowers the total electricity purchase cost of the microgrids by approximately 11%, thereby enhancing both voltage stability and economic efficiency of the system.