Enhancing The Utilization of Existing Solar Inverter by Incorporating Reactive Power Compensation Feature

Abstract

Listen

Translate article

Solar photovoltaic inverters plays a vital role in converting solar power into electrical energy and are programmed to operate at unity power factor. The active power pumped by solar inverter into grid is a function of solar irradiance which means that these inverters will not be able to operate at its rated capacity for whole range of irradiance. This lead to underutilization of the solar inverter resource. The capacity utilization of the existing solar inverter for the whole operational irradiance range can be improved by programming the solar inverter for reactive power compensation. Various strategies of reactive power compensation are Fixed Reactive power, Fixed Power factor, Power factor versus Active power and Volt-VAR. For all the control strategies, the inverter can be programmed such that the inverter operates at maximum power point tracking (MPPT) if abundant solar irradiance is available and the grid voltage is within limits. This means that during this condition, the complete solar PV generation is fed to the grid in the form of active power. However, if the clouds block the sun and causes the photovoltaic array's maximum power to drop below the set value, then the inverter will deliver reactive power based on reactive power command. This will enable the PV system to utilize the unused capacity of the solar inverter which otherwise would not be used when the solar inverter is operated at unity power factor. This paper discusses the various control strategies for reactive power compensation in grid tied solar inverter for enhanced utilization. Hardware results of the developed 5 kV A prototype of solar inverter for reactive power compensation are also presented and discussed in terms of the effective utilization of the solar inverter. This paper also discusses the proposed flowchart for various control modes of the smart grid connected solar inverter. The developed solar inverter could feed both active and reactive power to the grid for almost full operational irradiance range which in turn ensures full capacity utilization of the solar inverter which is not possible with unity power factor mode operation.