Abstract:The ascending trend of photo-voltaic (PV) utilization on a domestic scale in Finland, calls for a technical aspects review of low voltage (LV) networks. This work investigates the technical factors that limit the PV hosting capacity, in realistic case networks, designed relative to different geographical areas of Finland. A Monte Carlo method based analysis was performed, in order to quantify the hosting capacity of the formulated networks, with balanced and unbalanced feeds, in PV systems and their limiting constraints were evaluated. Finally, the effectiveness of on-load tap changer (OLTC) in increasing the PV penetration, when employed in the LV system, was investigated.

The direction taken towards sustainable power system and renewable energy generation is now irreversible. The power grid needs to host more renewable energy sources, such as solar power, and tackle power quality problems that come along with it. In this paper, firstly, the Hosting Capacities (HCs), of Photo-Voltaic (PV), were found for various regions and their limiting constraints were defined. Afterwards, comparison was made with the HC values obtained for different voltage value standards defined by various countries. Next, single-phase PV connection percentages in the network were defined that makes the voltage unbalance the limiting factor for HC. Lastly, the HC of the solar generation coupled with a Battery Energy Storage System (BESS) was assessed for the Finnish Low-Voltage (LV) grids. Different BESS-based scenarios were employed and their impact on voltage unbalance and HCs were observed. Finally, also the load voltage unbalance was incorporated to make the approach realistic and its impact on HC was analyzed. Results reveal that, depending on the connection strategy, the BESS can increase as well as decrease the HC based on voltage unbalance criteria. However, the load voltage unbalance has little effect on the solar HC values.

The low voltage (LV) network's constraints are prone to violations with the introduction of distributed energy resources at the customer vicinity. This study assesses the technical aspects of the realistic Finnish distribution network with varying photovoltaic (PV) penetration and quantifies the hosting capacities (HCs) of different regions. Moreover, to maximize the network's HC, having the overvoltage issue, different voltage control strategies are employed comprising on-load tap changer (OLTC), reactive power control (RPC) of inverters, network reinforcement (NR), and hybrid approaches. HC relative to different country-specific over-voltage limits are defined and the best voltage control technique is assessed, utilizing the stochastic approach of Monte Carlo simulations to model the uncertainty in the LV network's probabilistic variables. Moreover, combined medium voltage (MV)/LV network simulations are conducted to compare with the LV only simulations results. Technically, NR is the best approach to maximize the HC of a particular region but economically it is not proven a feasible one. The results presented that the OLTC employment will maximize the PV penetration if the overvoltage limit derived from EN 50160 is implemented and doubles the HC in the stricter-voltage-limits' scenarios, which can be maximized by the RPC inclusion in cohesion with OLTC. Moreover, RPC only strategy can be employed in the cases of low PV penetration scenarios, when OLTC will be proven the more expensive option. As the voltage violation limit becomes stricter, the hybrid approach of OLTC and RPC will be the best strategy. INDEX TERMS Hosting capacity, photovoltaic systems, on-load tap changer, reactive power control, distribution network.

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For the past few years, the world has seen a great shift toward renewable energy resources from conventional ones. But the ever‐increasing integration of distributed generation (DG) to the electrical network leads to integration limiting constraints like overvoltage, under voltage, harmonics, equipment ampacity violations, and failure of protection schemes. Therefore, an extensive investigation of the methodologies in which DGs can be incorporated into the electrical network is presented in this manuscript. This article provides an extensive review of all the hosting capacity (HC) terms, references, limiting constraints of the studied networks, geographical segregation, and their determination methodologies. Moreover, the factors defining the HCs of various networks and the architectures employed to increase them, are also explained briefly in the conducted review study.