With the growing need for transitioning to clean energy, increasing the share of renewable energy sources has become a global priority. The integration of distributed energy resources (DERs), such as photovoltaic (PV) and wind turbine (WT) systems, is crucial for optimizing the current distribution systems. Despite its benefits, DER integration presents technical challenges. DERs can cause rapid power output changes, leading to voltage instability and overvoltage, thereby impacting the power quality and equipment reliability. Mitigating this instability often requires costly grid infrastructure upgrades. Therefore, optimizing existing networks is essential to reduce these costs. To achieve this, the voltage profile of the target area must be thoroughly assessed and locations suitable for DER integration must be identified to ensure stable operation and voltage stability. This study proposes a new evaluation index, the Voltage Margin Evaluation Index (VMEI), to address the limitations of the existing indices. This index evaluates voltage stability and promotes DER integration in a region. Using the VMEI, we assessed the suitability of DER integration in Jeju, South Korea. Results demonstrate that integrating a 0.5 MW DER at Node 37 in Feeder 5, the optimal point with a VMEI of 1.00066, maintained the maximum voltage at 22.97 kV within the regulated range and improved voltage stability. Conversely, Node 29 in Feeder 4, with the lowest VMEI of 0.97262, resulted in a maximum voltage of 23.84 kV, exceeding the voltage regulation range, demonstrating that VMEI effectively identifies suitable DER integration points. This study provides valuable insights for improving DER integration into distribution systems, aiding the global transition to sustainable energy.

Renewable energy sources are being increasingly deployed to achieve carbon neutrality, thereby boosting photovoltaic (PV) system adoptions. Accordingly, vertical PV systems designed for specific installations have been developed. We propose a strategy to enhance the PV hosting capacity of a connected distribution line (DL) by combining vertical installations with modules facing east-west and conventional PV systems with modules facing south at an installation angle of approximately 30°. The data were obtained from a real testbed located in South Korea, which is situated in a mid-latitude region. We analyzed the generation patterns of vertical and combined PV systems (vertical and conventional) to enhance the hosting capacity. The results showed that vertical PV combination ratios of 40–60% effectively flattened the peak generation curve. Additionally, the DL hosting capacity improved by 40% under real-world conditions. In an actual industrial scenario, the system feasibility was validated to be within the voltage maintenance range and thermal capacity of lines in South Korea, indicating that this approach can mitigate the need for additional line installations and renewable energy curtailments. Furthermore, the issue of Duck Curves in the power grid can be addressed by smoothing the power production of the PV systems, particularly during low-demand periods.

The surge in distributed energy resources, driven by the 2030 renewable energy policy, has resulted in a notable increase in the adoption of photovoltaic systems. However, the proliferation of photovoltaic generation has introduced over-voltage challenges, thereby constraining its hosting capacity. Consequently, there has been a growing body of research aimed at addressing these over-voltage issues through the utilization of smart inverters, SVR, and ESS deployment. This paper presents a methodology for Energy Storage Systems(ESS) to control reactive power. To assess the potential hosting capacity, we calculate voltage across two distinct Volt-VAR curve types. The study provides a comprehensive analysis of the impact of the Volt-VAR curve, employing OpenDSS for quasi-static time-series simulations while considering the attributes of the distribution system model under various scenarios.

The increasing interest of the Nationally determined contributions (NDC) to reduce national emissions has given rise to the need for turning our attention to new renewable energy sources, especially photovoltaic (PV) generation. To evaluate the impact of interconnecting PV and railway systems in Korea Railroad (Korail), this study analyzes the power system configurations and the load characteristics of railway system in Korail. In addition, the impact of System Marginal Price (SMP) variations and renewable energy policies on the introduction of renewable energy in electric railways was analyzed. Also, the PV power generation types applicable to electric railways is presented. Through a case study applied to Korail Line 1 station between Guro and Suwon, economic benefits from the introduction of vertical photovoltaic power generation are analyzed.