Researchers Develop Method to Control Voltage Fluctuations in Solar+Storage Systems

Researchers at the National Institute of Technology Kurukshetra have claimed to have developed a new method to regulate direct current (DC) voltage for grid-connected solar photovoltaic plus battery energy storage (SPV-BES) systems.

The researchers explained that power system engineers faced several technical challenges due to the high-penetration of renewable energy into the distributed generations. The voltage level increases due to the active power supply from solar to the distribution system. The issue becomes severe when solar power generation is at its peak during the day time.

The researchers developed a new technique for the coordinated regulation of active and reactive power compensation of grid-connected solar plus battery storage. They utilized a curve fitting toolbox in Simulink (graphical programming for simulation) to derive the controller equation for the new DC voltage regulator. To verify the proposed system’s effectiveness, the researchers simulated variations in solar irradiance and load changes.

The researchers integrated the maximum power point tracking (MPPT) algorithm in the control setup to take out the peak power output from solar at any instance under the variable operating conditions. The battery will be charged when the solar irradiance is higher than a particular value decided by the voltage measurement of SPV. It will be discharged when the solar system cannot supply the load due to reduced solar irradiance as the converter allows the energy to flow in both directions.

The researchers connected the solar system with the DC link capacitor through DC to DC converter and coupled BES to the DC link capacitor through buck-boost DC to DC converter to develop the control structure. They also used DC to AC converter to connect the DC side of the structure with the AC side and coupled variable AC loads at the point of common coupling (PCC).

“The control structure measures the voltages at PCC as well as grid-side and current at load and SPV-BES side. The signals are fed to the controller to perform energy flow management,” said the researchers.

In the report, the researchers stated that the control structure enables the SPV-BES system to supply active power and compensate reactive power at the point of common coupling. The control structure also utilized a hybrid system’s capability to compensate reactive power for enhancing the system stability and power equality, they added.

Last month, two researchers from the Indian Institute of Technology (IIT) Kanpur claimed to have fabricated sub-modules from organic photovoltaic cells on paper substrates.

Recently, researchers at TU Graz University claimed that they had developed a redox flow battery that utilizes conventional vanillin instead of liquid electrolyte, which could make the battery more environment friendly. Redox flow batteries are electrochemical energy storage devices that convert chemical energy into electrical energy through reversible oxidation and reduction of working fluids.

Image credit: ChristofferRiemer, CC BY 3.0, via Wikimedia Commons