Energy Management of a Hybrid Photovoltaic-Fuel Cell Grid-Connected Power Plant with Low Voltage Ride-Through Control

TL;DR

This paper proposes an energy management and control scheme for a hybrid photovoltaic-fuel cell power plant that ensures flexible power supply and supports grid stability during voltage sags, complying with modern grid codes.

Contribution

It introduces a novel energy management algorithm and low voltage ride-through control that operate without complex phase-locked loops, enhancing grid support capabilities.

Findings

Effective power management between PV and fuel cells demonstrated.

System maintains sinusoidal currents during voltage sags without PLL.

Control system reduces computational complexity while supporting grid stability.

Abstract

An energy management scheme is presented for a grid-connected hybrid power system comprising of a photovoltaic generator as the primary power source and fuel-cell stacks as backup generation. Power production is managed between the two sources such that a flexible operation is achieved, allowing the hybrid power system to supply a desired power demand by the grid operator. In addition, the energy management algorithm and the control system are designed such that the hybrid power system supports the grid in case of both symmetrical and asymmetrical voltage sags, thus, adding low voltage ride-through capability, a requirement imposed by a number of modern grid codes on distributed generation. During asymmetrical voltage sags, the injected active power is kept constant and grid currents are maintained sinusoidal with low harmonic content without requiring a phase locked loop or positive-negative sequence extraction, hence, lowering the computational complexity and design requirements of the control system. Several test case scenarios are simulated using detailed component models using the SimPowerSystems toolbox of MATLAB/Simulink computing environment to demonstrate effectiveness of the proposed energy management control system under normal operating conditions and voltage sags.