Stochastic Approach for Increasing the PV Hosting Capacity of a Low-Voltage Distribution Network

Abstract

In recent years, the emerging fear of an energy crisis in central Europe has caused an increased demand for distributed energy resources (DER), especially small photovoltaic rooftop installations up to 10 kWp. From a technical point of view, distributed PV in low-voltage networks is associated with the risk of power quality violation, overvoltage, voltage unbalance, harmonics, and violation of the thermal limit of phase conductors, neutral conductors, and transformers. Distribution system operators (DSO) are currently in a position to determine the amount of installed PV power for which reliable and safe network operation is ensured, also known as the photovoltaic hosting capacity (PVHC). The presented study describes a stochastic methodology for PVHC estimation and uses it to analyze a typical LV rural network in the Slovak Republic. Detailed and precise calculations are performed on the 4-wire LV model with accurate results. In this study, we, thus, profoundly analyze the problems with voltage violation, unbalanced voltage energy losses, and the thermal loading effect of increasing PV penetration. The results show that overvoltage events are the main factor limiting the PVHC in LV systems. This conclusion is in accordance with the experience of the DSO in the Slovak and Czech Republic. Subsequently, the study focuses on the possibilities of increasing PVHC using those tools typically available for DSO, such as changes in PV inverter power factors and no-load tap changer transformers. The results are compared with those derived from similar analyses, but we ultimately find that the proposed solution is problematic due to the high variability of approaches and boundary conditions. In conclusion, the paper discusses the issue of the acceptable risk of overvoltage violation in the context of PVHC and lowering losses in LV networks.

Impact of Prosumers’ Operation on Selected Parameters of Low-Voltage Distribution Network Operation

“…A similar problem with the impact of a large numbers of prosumers with PV installations is noticed in the Slovak Republic, and the results of the study describe a stochastic methodology for PVHC estimation and use it to analyze a typical rural network of LV, presented in [9].…”

A Comprehensive Review on Recent Developments of Hosting Capacity Estimation and Optimization for Active Distribution Networks

“…Moreover, it is essential to operate in parallel with other voltage control techniques to avoid voltage instability during heavy loads that caused power blackouts [109]. Many articles studied the OLTC transformer as an efficient HC improvement technique for emerging grids in [312]- [314].…”

Expert System Integrating Rule-Based Reasoning to Voltage Control in PV-Rich Low Voltage Electric Distribution Networks

“…Some researchers have attempted to define it concerning the transformer capacity [24], while others have calculated it as the ratio of installed PV peak capacity to the maximum load of the feeder [1]. Some definitions have even replaced the "maximum load of feeder" with "minimum load of feeder" [25], considering the ratio between the actual PV output and the active power load. But, the most accessible, clear, and easy-to-understand definition refers to the number of PV prosumers from the end-users connected in the LV EDNs [19,26].…”