article · Scientific Reports
Integrating large-scale solar photovoltaic systems can improve voltage stability in weak national grids, serving as an alternative to aged shunt reactors used to control overvoltage issues in Northern Nigeria. A study evaluating the Nigerian power grid compared two deployment strategies with increasing penetration levels: centralised solar generation at a critical bus and dispersed solar generation across multiple weak buses. Voltage stability was assessed using active power margin, reactive power margin, and the critical voltage-reactive power ratio index. Simulations reveal that dispersed solar installations bring the highest bus voltage into acceptable limits at a penetration level of 21.44 percent (800 megawatts), compared to 26.29 percent (1,000 megawatts) for centralised generation. Overall, dispersed solar generation provides superior voltage stability improvements across all evaluated metrics while supporting growing energy demands.
Weak national electricity grids often suffer from instability and voltage problems, requiring costly equipment to manage. Demonstrating that distributed solar power plants can stabilise transmission networks while generating clean energy offers electricity network planners a dual-purpose strategy. This approach helps modernise ageing infrastructure, reduce overvoltages, and harness solar energy to meet increasing electricity demand in developing energy systems.
This simulation-based research is at an applied modelling stage, having been evaluated using software models of the Nigerian transmission network. It provides planning insights for transmission system operators, energy regulators, and utility-scale solar developers. The findings can inform siting and capacity requirements for new grid-connected solar plants to enhance network stability, though real-world deployment requires progressing beyond digital simulations to field trials and utility procurement frameworks.
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This paper investigates the application of large-scale solar photovoltaic (SPV) system for voltage stability improvement of weak national grids. Large-scale SPV integration has been investigated on the Nigerian power system to enhance voltage stability and as a viable alternative to the aged shunt reactors currently being used in the Nigerian national grid to mitigate overvoltage issues in Northern Nigeria. Two scenarios of increasing SPV penetration level (PL) are investigated in this work, namely, centralized large-scale SPV at the critical bus and dispersed large-scale SPV across the weak buses. The voltage stability of the system is evaluated using the active power margin (APM) also called megawatt margin (MWM) derived from Active Power-Voltage (P-V) analysis, the reactive power margin (RPM) and the associated critical voltage-reactive power ratio (CVQR) index obtained from Reactive Power-Voltage (Q-V) analysis. All simulations are carried out in DIgSILENT PowerFactory software and result analyses done with MATLAB. The results show that with centralized SPV generation for the case study system, the highest bus voltage is able to fall within acceptable limits at 26.29% (1000 MW), while the dispersed SPV achieves this at 21.44% (800 MW). Also, the dispersed SPV scenario provides better voltage stability improvement for the system as indicated by the MWM, RPM and the CVQR index of the system. Therefore, this work provides a baseline insight on the potential application of large-scale SPV in weak grids such as the Nigerian case to address the voltage stability problems in the power system while utilizing the abundant solar resource to meet the increasing energy demand.
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DOI: 10.1038/s41598-021-04300-w
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