Energy management of DC microgrid based on photovoltaic combined with diesel generator and supercapacitor
Résumé
Microgrid is promoted as an economical and efficient energy system in which different renewable sources and storage are interconnected to meet the load power demand at any time. It can operate in on-grid and off-grid mode. Since the electrical contribution of each renewable energy source is dependent on the variation of its resource and the load power demand changes time to time, it is possible that the microgrid cannot generate enough electricity at some time. Thus, especially in off-grid mode, a diesel generator is needed as another backup power. However, due to the slow dynamic behavior of the diesel generator start-up stage, the power quality is lowered down because of the shortage of power. Therefore, during the period of the diesel generator starting up, a supercapacitor is suggested to compensate the power balance because of its fast response and high power density. In addition, the supercapacitor can be also used to overcome the electrochemical storage limits like its state of charge and maximum current. This paper proposes a method for power balance control of a hybrid multisource DC microgrid system aiming to meet the load power demand with reliability and stabilizing the DC bus voltage. In order to realize this function, an experimental platform has been set up and the energy management strategy has been implemented into the control process. The experimental results show that the designed control strategy improves the DC microgrid dynamic and static performances under such operating conditions.