Power management and economic load dispatch based control of hybrid PV-battery-diesel standalone AC system

Abstract

This paper presents a power management strategy with consideration to the economical operation of a hybrid photovoltaic(PV), battery (BESS) and diesel generator (DG) system. The components of a hybrid system complements the characteristics of each other and tends to improve the reliability of the system. However, a coordinated power management strategy among the individual components is crucial for reliable system operation under load and source power imbalances. In this work, a DC synchronization of DG with PV-BESS is proposed to achieve improved power sharing and coordination as compared to a typical ac synchronization approach. The DG is connected to the common DC link through a controlled VSC while the PV & BESS system is connected through DC-DC converters respectively. The decentralized power sharing among the DG, PV & BESS is achieved through DC droop approach while the remote end AC loads are fed through a voltage source inverter (VSI) operating in the grid-forming mode. The proposed power management strategy incorporates off-MPPT operation of PV as well as efficient operation of DG, under critical power imbalances. Further a secondary control based on Economic Load Dispatch (ELD) is proposed for the optimal operation of the hybrid system taking BESS's State of Charge (SoC) into account. The proposed power management and ELD based control scheme is verified though real-time simulation carried out under wide variations in system condition.