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In order to reduce the impact of current and voltage effectively, when the dual-mode inverter grid-connected/off-grid mode transfer in the micro-grid system. There is a uncontrollable parameter perturbations influence in the transfer process of grid-connected/off-grid. This paper presents micro-grid dual-mode inverter which take H ∞ robust controller in current inner loop, reducing external disturbances and parameter perturbations influence, and enhancing power quality during grid-connected/off-grid mode transfer. Relying on a southern reef stand-alone micro-grid system project, taking simulation and experimental tests, comparative analysis with traditional PI control shows the superiority of the proposed scheme.

For Micro-Grid in islanded operation, due to the effects of mismatched line impedance, the real and reactive power could not be shared accurately with the conventional droop control method, which would likely cause circulation current problems. Generally, the real power sharing is achieved by P-f droop control equation and the reactive power by Q-V. This study present an improved scheme for adaptive droop coefficients to share the burden according to the available headroom of each converter station. Real-time simulation results show effectiveness and feasibility performance of the proprosed adaptive droop control.

In order to realize the uninterruptible power supply in the master-slave independent micro-grid system, the micro-grid inverter needs to realize the mode switching of the grid-connection/grid-disconnection. How to reduce the transient oscillation during switching, so as to effectively achieve seamless mode switching is a key issue to be solved. In this paper, a typical master-slave control independent micro-grid is used as an example, the strategy of mode switching is improved in two aspects. On the one hand, the state-following algorithm is adopted to improve the switching strategy of the outer loop. On the other hand, the current inner loop is taken by the H∞ robust controller to improve the robustness of the controller. Compared with the traditional PI control mode switching, this paper illustrates the feasibility of the proposed strategy through the simulation and experiment verification. The improvement strategy in this paper can effectively reduce the voltage and current oscillation during mode switching.

Stability and H-infinity optimal control of nonlinear networked control systems (NNCSs) with distributed delays and disturbance are studied in this paper. We develop a hybrid Takagi-Sugeno fuzzy model for nonlinear plant interconnected with continuously dynamic output feedback controller. Sufficient conditions are derived by constructing Lyapunov-krasovskii functional, which insure that the system is asymptotically stable and could achieve γ — suboptimal H-infinity stabilization. Approach to obtaining disturbance attenuation level and parameters of sub-/optimal controller is given in the form of linear matrix inequalities.