Voltage support for industrial distribution network by using positive/negative sequence passivity-based control

The voltage of point of common coupling (PCC) connects industrial distribution networks to the utility grid. Asymmetric sags often occur at PCC due to large load changes. To tackle this challenge, the energy storage system (ESS) is employed to improve the voltage stability of industrial distribution networks. However, there is lack of effective control methods to improve the stability of grid since the unstable energy control rate of ESS. Passivity-based control (PBC), which makes the unstable objects and energy storage resources into a passive system, is applied to improve the voltage stability. PBC is an energy-based approach, which aims to render the closed-loop system with a given storage function. In this paper, a PBC strategy based on euler-lagrange (EL) model is proposed for industrial distribution networks under asymmetrical utility grid voltage sag conditions. According to the passive control theory, the passivity based controller is designed by a new positive/negative sequence damping injection method. The power distribution of parallel-connected multiple inverters has been investigated to achieve coordinated operation. Simulation results verify the effectiveness of the proposed control strategy, such as faster response, good stability, and better voltage support performance.