A Stochastic Assessment of PV Hosting Capacity Enhancement in Distribution Network Utilizing Voltage Support Techniques

Abstract

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.

Review on the PV Hosting Capacity in Distribution Networks

“…The coordinated application of OLTC and Smart Inverters improved HC from 9.3 MW to 24 MW as compared to the 17 MW increase with only Smart Inverter's application in an EPRI's 34.5-kV test circuit in [27]. The OLTC inclusion in terms of economical constraints and increased network losses is discussed in [29,31,70,114]. The economic aspects of the proposed method need proper consideration and OLTC is discussed as an expensive voltage regulation approach in the LV network in [29] but their operation becomes indispensable in case of increased penetration of PVs.…”

“…Therefore, the application of advanced voltage control methods is crucial for accommodating the ever-increasing penetration of PV Distributed Generation (DG) and achieving relatively fast response time as compared to legacy devices. The authors of [28][29][30][31] considered OLTC as a means to increase HC by voltage regulation. PV inverters and battery storages are good alternatives to voltage regulators due to the slow response time of the latter.…”

Comparison of Voltage Control by Inverters for Improving the PV Penetration in Low Voltage Networks

“…It varies widely among researchers. Some researchers have defined it as the ratio of the total installed PV capacity of the network and the feeding transformer's capacity [23], while others have calculated it as the ratio of installed PV peak capacity to the feeder maximum load [26]. Some have even replaced the "feeder maximum load" with "feeder minimum load" in these ratios.…”

“…In addition, other feeders that are connected to the same transformer may be adversely impacted by this action. Besides, the voltage regulation devices like On-Load Tap Changing transformer (OLTC), Switched Capacitor Bank (SCB), and Step Voltage Regulator (SVR) are slow to operate and usually are very sensitive to the number of operations [9], [10]. High share of PV penetration combined with intermittency of PV systems on the feeder may cause excessive and unnecessary operations of these devices.…”

Tie-line Power Flow Control Method for Grid-connected Microgrids with SMES Based on Optimization and Fuzzy Logic

“…Nowadays, grid integration of PV is becoming the most important and fastest-growing form of electricity generation among renewable energies. However, The output power generation of PV has an intermittent nature due to cloud transients [5], [6]. The high penetration of PV can cause several problems such as the fluctuation in tie-line power between the utility power grid and the MG, the voltage rise/dip at point of common coupling (PCC), the violation of power line capability, and the high line power loss.…”