A three-layer voltage balancing control strategy for DC capacitor is proposed to solve the DC capacitor voltage unbalance problem of electrical energy router under power grid failure. Based on the theoretical analysis of the unbalance power

the injection of zero-sequence voltage and negative-sequence current can flexibly share the responsibility of inter-phase unbalance power by dynamically adjusting the defined weighting coefficient

which improves the control freedom of the system. The simulation platform of electrical energy router is established in MATLAB/Simulink. The simulation results show that

when a single-phase failure(95% grid-voltage sag)occurs

the voltage balancing control goal of DC capacitor in electrical energy router can be achieved by independently using the injections of the single zero-sequence voltage

the weighted integration of zero-sequence voltage and negative-sequence current

or the single negative-sequence current.