In the quest for cleaner, more reliable energy, researchers are constantly seeking innovative solutions to harness solar power more effectively. Ke Zhou, from the Electric Power Research Institute of Guizhou Power Grid Co., Ltd., has made significant strides in this area with a novel approach to stabilizing photovoltaic (PV) power generation systems. His recent study, published in ‘Energies’, introduces a hybrid energy storage system (HESS) that combines fuel cells (FCs) and supercapacitors (SCs) to smooth out the fluctuations in PV output power, a persistent challenge in the industry.
The core of Zhou’s research lies in the integration of a fuel cell/supercapacitor hybrid energy storage device (FSHESS) with a grid-connected PV system. This hybrid system acts as a buffer, absorbing excess power when PV output is high and supplying power when output is low. “The FSHESS can undertake the power difference that originally needs to be compensated by the distribution network, which reduces the frequent disturbances to the distribution network,” Zhou explains. This not only enhances the stability of the grid but also increases the utilization of solar energy.
One of the key innovations in Zhou’s work is the power allocation strategy for the FSHESS. Unlike traditional energy storage systems, which often rely on a single type of storage device, the FSHESS leverages the unique strengths of both FCs and SCs. FCs provide high energy density and environmental friendliness, while SCs offer high power density and long cycle life. The challenge, however, is managing the unidirectional power flow of FCs and the limited capacitance of SCs. Zhou’s solution involves a rule-based low-pass filtering method that ensures the SC’s state of charge (SOC) remains within a safe range, preventing overcharging or deep discharging.
On the control front, Zhou addresses the issue of DC-bus voltage stabilization, a critical aspect of maintaining system efficiency and stability. Traditional PI controllers often struggle with large deviations in voltage, leading to overshoot and oscillation. Zhou’s modified variable speed integral nonlinear PI controller adapts to these deviations, providing a more stable and efficient control mechanism. “The modified variable speed integral nonlinear PI control algorithm for the DC-bus voltage control can adaptively adjust the strength of the integral action according to the actual deviation between the reference value and real-time measurement of the DC-bus voltage,” Zhou states. This adaptive control not only reduces overshoot and oscillation but also minimizes power loss.
The implications of Zhou’s research are far-reaching. For the energy sector, this technology promises more stable and efficient integration of solar power into the grid. It could lead to increased adoption of PV systems, as utilities and consumers alike benefit from reduced grid disturbances and improved energy utilization. Moreover, the hybrid energy storage approach could pave the way for more sophisticated energy management systems, capable of handling the intermittent nature of renewable energy sources more effectively.
As the world continues to shift towards renewable energy, innovations like Zhou’s FSHESS could play a pivotal role in shaping the future of the energy landscape. By addressing the challenges of PV power fluctuations and grid stability, this research opens new avenues for commercial applications, potentially revolutionizing how we store and distribute clean energy.
