Analysis of Voltage Rise Phenomena in Electrical Power Network With High Concentration of Renewable Distributed Generations

The increasing penetration levels of Renewable Distributed Generation (RDG) into power system have proven to bring both positive and negative impacts. The occurrence of under voltage at the far end of a conventional Distribution Network (DN) may not raise concern anymore with RDGs integration into the power system. However, a high penetration of RDG into power system may cause problems such as voltage rise or over-voltage and reverse power flows at the Point of Common Coupling (PCC) between RDG and DN. This research paper presents the voltage rise and reverse power flow effects in power system with high concentration of RDG. The analysis is conducted on a sample DN, i.e., IEEE 13-bus test system, with RDG by considering the most critical scenario such as low power demand and peak power injection to DN from RDG. The Simulations are carried out using MATLAB/Simulink software, a mathematical model of a distribution grid, integrating RDG is developed for studying the effects of voltage rise and bidirectional flow of power. Furthermore, a control strategy is proposed to be installed at PCC of the DN to control/or mitigate the voltage rise effects and to limit the reverse power flow when operating in a worst critical scenario of minimum load and maximum generation from RDG. The proposed control strategy also mitigates the voltage-current harmonic signals, improve the power factor, and voltage stability at PCC. Finally, recommendations are provided for the utility and independent power producer to counteract the effects of voltage rise at PCC. The study demonstrated that, PCC voltage can be sustained with a high concentration of RDG during a worst-case scenario without a reverse power flow and voltage rise beyond grid code limits.

Study of Influential Factors on the Dielectric Strength of [UPE/BaTiO3] Nanocomposites

Unsaturated polyester resin (UPE) was used as a base material and barium titanite nanoparticles (BaTiO3) (50-7-nm) as a support material, with different weight ratios (0.25,0.75,1.25,2 wt%), to prepare a nanocomposite material. The research models were prepared according to the standard specifications and with different thicknesses (≈ 1.1,1.8,2.2,2.7 mm) to show the effect of thickness, number of cycles, percentage of addition and voltage rise rate at (5 kv/s and 0.5 kv/s) on the dielectric strength (Ebr) of the prepared material. The results showed that Ebr decreased with increasing the thickness of the material, BaTiO3 additive rate and the number of cycles. Dielectric strength (Ebr) increases with increasing of voltage rise rate.

Voltage Rise Regulation with a Grid Connected Solar Photovoltaic System

Renewable Distributed Generation (RDG), when connected to a Distribution Network (DN), suffers from power quality issues because of the distorted currents drawn from the loads connected to the network over generation of active power injection at the Point of Common Coupling (PCC). This research paper presents the voltage rise regulation strategy at the PCC to enhance power quality and continuous operation of RDG, such as Photovoltaic Arrays (PVAs) connected to a DN. If the PCC voltage is not regulated, the penetration levels of the renewable energy integration to a DN will be limited or may be ultimately disconnected in the case of a voltage rise issue. The network is maintained in both unity power factor and voltage regulation mode, depending on the condition of the voltage fluctuation occurrences at the PCC. The research investigation shows that variation in the consumer’s loads (reduction) causes an increase in the power generated from the PVA, resulting in an increase in the grid current amplitude, reduction in the voltage of the feeder impedance and an increase in the phase voltage amplitude at the PCC. When the system is undergoing unity power factor mode, PCC voltage amplitude tends to rises with the loads. Its phase voltage amplitude rises above an acceptable range with no-loads which are not in agreement, as specified in the IEEE-1547 and Southern Africa grid code prerequisite. Incremental Conduction with Integral Regulator bases (IC + PI) are employed to access and regulate PVA generation, while the unwanted grid current distortions are attenuated from the network using an in-loop second order integral filtering circuit algorithm. Hence, the voltage rise at the PCC is mitigated through the generation of positive reactive power to the grid from the Distribution Static Compensator (DSTATCOM), thereby regulating the phase voltage. The simulation study is carried out in a MATLAB/Simulink environment for PVA performance.

VOLTAGE REGULATION CONTROL USING BATTERY ENERGY STORAGE SYSTEM IN DISTRIBUTION NETWORK WITH HIGH PV PENETRATION STRENGTH

In recent years, the increasing integration of PV generations into distribution network systems is becoming a huge concern as it introduces various complications such as voltage rise problems, especially during high PV penetration levels. Conventional mitigation methods using voltage regulating devices are not designed to mitigate this particular problem while emerging methods requires sacrifices in term of cost and profit to be made by PV system owners. Thus, mitigation using a battery energy storage system (BESS) is proposed in this paper, where it is specifically designed to solve the voltage rise problem in the distribution system during high PV penetration. This is achieved by controlling the charging and discharging of the BESS accordingly. To validate the effectiveness of the proposed BESS, a simulation using MATLAB/Simulink software of 25 distributed PV generations with respective loads connected to a distribution network power system is done. The penetration level is set from 0% to 100% and the voltage level is measured at the point of common coupling for each increment. The findings show that the BESS can regulate the voltage rise that occurred during high PV penetration of 80% and 100% from 1.11 p.u. and 1.13 p.u. to an acceptable voltage of 1.01 pu.