Impact of Low Short-Circuit Capacity Grid on the Performance of Passive Harmonic Filters in Grid-Tied Solar PV Systems

The global adoption of grid-tied solar PV systems has grown significantly, driven by their cost-effectiveness and potential to reduce electricity bills. Grid-tied renewable energy systems inject harmonics into the grid network due to power electronics components, non-linear loads, and intermittency. To mitigate these harmonics and maintain total harmonic distortion (THD) within acceptable IEEE tolerance, either passive, active, or hybrid filtering techniques may be employed. Despite these harmonic mitigation strategies, challenges persist, particularly in grid networks with low short-circuit capacity. Such grid networks may be due to distant transmission and generation lines. Therefore, this study investigates the impact of low short-circuit capacity grid conditions on the performance of passive filters in a grid-tied solar PV system. A shunt passive filter consisting of three identical single-tuned series RLC branches per phase and an RL branch in the neutral phase has been used. The filter has proved to reduce the current and voltage THD to allowable values of 2.3% and 3.7%, respectively. However, the inclusion of a grid network that experiences low short-circuit capacity conditions proved to degrade the performance of the passive filter, as the THD of both grid voltage and current increased to 3.7% and 5.7%, respectively.