Abstract
In a photovoltaic DC microgrid, the intermittent power supply of the distributed generation and the fluctuation of the load power will cause the instability of the bus voltage. An improved super-twisting sliding mode control method based on the super-twisting algorithm is proposed to solve this problem. In this paper, a bidirectional half-bridge buck–boost converter was selected as the research topic. The proposed control method replaces the sign function with the saturation function to further mitigate the chattering effect. The stability of the proposed control method was proven to be finite-time convergent using the Lyapunov theory control. Compared with PI control, linear sliding mode control, and terminal sliding mode control, the proposed control method reduces the system overshoot by up to 33% and greatly improves the response speed; compared with the traditional super-twisting sliding mode control method, the system overshoot is reduced by 6.8%, and the response speed is increased by 38%. The experimental results show that the proposed control method can reduce the fluctuation range of the bus voltage, shorten the time of bus voltage stability, effectively stabilize the bus voltage of the photovoltaic DC microgrid, and maintain strong robustness.
Highlights
Academic Editor: Marco PasettiEnergy shortage and environmental pollution are key problems of human development
In [5], a two-stage control scheme was adopted for a hybrid AC–DC microgrid, and a sliding mode controller was used as the local controller
In order to solve the unreliability of distributed generation, it is necessary to introduce an energy storage device to “cut peaks and fill valleys” of a DC microgrid, that is, when the electric energy generated by the power supply is greater than the total load, the remaining energy will be stored in the energy storage unit and can be fed to the public grid
Summary
Energy shortage and environmental pollution are key problems of human development. As a clean energy, solar energy is increasingly used in power systems. In [5], a two-stage control scheme was adopted for a hybrid AC–DC microgrid, and a sliding mode controller was used as the local controller Experiments show that this control method can effectively improve the stability and robustness of the system. As a typical second-order sliding mode control (SOSMC), super-twisting sliding mode control (STSMC) applies discontinuous control variables to the high-order derivatives of the sliding mode surface, which effectively suppresses chattering and improves the global robustness of the system. In [16], an energy management control method using the super-twisting fractional method was proposed, which can reduce the chattering and steady-state error of the bus voltage in the presence of uncertainty. The simulation results show that the proposed control method can effectively improve the system response speed and reduce the system overshoot and the system chattering amplitude.
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