Impact of DG and EV loading on Distribution Network and its Protection using SEL351-S Protection Units

However, high penetration of DG sources can cause stability and protection issues in the distribution system network, resulting in transients in voltage and current profiles. Additionally, Plug-in Electric Vehicles' (PEV) charging from the low-voltage distribution network can impact the system in terms of voltage unbalance and transformer overloading. The impact of DG penetration on the distribution system is a critical concern, as it can lead to loss of relay coordination and mal-operation of the system. Studies have shown that with increased DG penetration, the Rate of Change of Frequency (ROCOF) increases when subjected to disturbances. Furthermore, the fault current also increases with DG penetration, posing greater damage risks to the system. To mitigate the negative impacts of DG penetration, various studies have proposed the use of different protection schemes. One such scheme involves the implementation of a differential protection system using the SEL-351S protection unit. This system measures the differences in phase currents and trips the breaker if the differences are not equal to zero, indicating a fault has occurred. A 9-mile long distribution network model was implemented to mimic the effects of DG penetration and PEV charging on the system. The model consisted of inductors and resistors to represent line impedances, and a variable transformer to create a variable potential difference in the circuit. The proposed protection scheme was tested using MATLAB/Simulink simulations and experimental results. The results showed that with both DG penetration and PEV charging, the differential protection failed to provide protection, indicating the need for a better protection scheme. The experimental setup of the distribution network was also presented, demonstrating the effectiveness of the proposed solution. The study highlights the importance of considering the impact of DG penetration and PEV charging on the distribution system and the need for effective protection schemes to mitigate these effects. The proposed differential protection system using the SEL-351S protection unit shows promise in providing reliable protection for the distribution network. The impact of DG penetration on the distribution system is a complex issue, and further research is needed to fully understand its effects. However, the proposed protection scheme and experimental results demonstrate the potential for improving the reliability and efficiency of the distribution network.