Performance Analysis Of Malaysian Low Voltage Distribution Network Under Different Solar Variability Days

The widespread of Photovoltaic (PV) systems as one of the distributed generation technologies could have profound impact on the distribution networks operation, particularly on network losses and network voltages fluctuations. This is mainly caused by the high PV penetrations coupled with high solar variability in the countries with large cloud cover. Therefore, this paper presents an investigation on the impact of residential grid-connected PV system by utilizing a typical low voltage (LV) network in Malaysia under various solar variability days. In this study, there are three scenarios; where, each scenario were performed with different levels of PV penetration and five different solar variability days. The impacts of PV system allocation in different scenarios and various solar variability days are assessed in term of voltage unbalance and network losses. The results propose that Scenario 1: randomly allocation of PV systems across the LV network has the lowest voltage unbalance and network losses especially during overcast day

Impact assessment of high penetration of rooftop PV in municipal electrical networks

Thesis (MEng (Electrical Engineering))--Cape Peninsula University of Technology, 2019There is an increasing global trend of grid connected distributed generation, mainly based on renewable energy sources such as wind and photovoltaic (PV) systems. The proliferation of these intermittent energy sources into the existing networks may subject the network into technical challenges such as voltage rise, equipment over-load, power quality and protection scheme violations. With increased PVDG (mainly rooftop PV) uptake occurring mostly on Low Voltage (LV) feeders, characterised by lack of network visibility and controllability, these technical challenges may be exac-erbated. In the absence of government incentive, current uptake of rooftop PVDG is reliant on customer preference and financial means. Thus make PVDG integration on the network be randomly placed and sized, of which the network distribution operator (NDO) will have no control over. The lack of regulations and interconnection studies conducted on South African networks has resulted in a growing concern amongst util-ities on how the increasing customer-owned rooftop PV systems uptake will impact the existing networks. This study aims to investigate technical impact high penetration of rooftop PV sys-tem will have on the existing LV networks. The load flow (LF) computation is pivotal in determining power system state when subjected to high penetration of rooftop PV. Monte-Carlo based Probabilistic Load Flow (PLF) was proposed and input variables were modelled using Beta probabilistic distribution function (PDF). The proposed im-pact assessment framework was applied on real LV urban residential network situated in Cape Town, South Africa. Simulations were conducted on DIgSILENT PowerFac-tory and the PDF for input variables (Load demand and PV generation) were derived from historic data. Four scenarios were simulated and system performance parameters were recorded such as; voltage magnitude, voltage unbalance factor and equipment thermal loading. Simulation results in the test network indicated thermal loading violation as the main limiting factor in urban residential network. PV system topology (either three-phase or single phase) proved to have significant effect on network hosting capacity, were higher PV penetration can be achieved for a three-phase system. Penetration level as low as 12% were recorded, which is significantly lower than the prescribed guidelines in simplified criteria in NRS097-2-3 standard and therefore raises a concern on the relevance of this standard on all types of networks (in urban network in particu-lar). However, penetration level above NRS097-2-3 limits may be achieved depending on feeder characteristics

Impact Of Integrating Solar PV System To Malaysian LV Network And Mitigation Using Distributed BESS

The current high demand for energy and increase in greenhouse gas emission have resulted in Renewable Energy (RE) sources gaining a lot of attention in effort to sustain future energy needs. Sustainable Energy Development Authority (SEDA) data show that the most popular RE in Malaysia is solar Photovoltaic (PV) energy which has the highest installed capacity with 66.95% total installed RE. However, connection of RE into the existing distribution networks can contribute to several network problems such as voltage flicker, reverse power flow, power fluctuations in grids and unintended islanding. More specifically, solar PV system with high variability can lead to output power fluctuation. This may worsen the performance of the distribution network. In addition, it is important to maintain the flexibility and stability of the system even in the event of disturbances or sudden changes in PV generation. Thus, this research aims to investigate the impact of solar PV integration on the Malaysian distribution network under various PV integration scenarios and solar variability. Analytical method was applied to determine the Battery Energy Storage System (BESS) capacity with the aim of reducing the negative impacts of PV integration on the network. A real Malaysian network was modelled in OpenDSS software and was utilized as the reference network. It is also important to highlight that there are three scenarios in this research which indicate where the PV system was installed namely, randomly allocated PV system, concentrated PV system installation across two feeders, and unbalanced allocation of PV system. Real PV variability data obtained from weather station installed at UTeM were collected at 5-minute intervals and were utilized to study their impacts on network distribution. A corresponding size of distributed BESS was modelled to store the excessive energy during low demand and deliver it during high demand. The findings suggest that randomly allocated PV systems are suitable for PV installation in residential areas. In addition, the result for BESS installation during high PV penetration showed significant improvement on the net load profile, and this can assist utility providers to deliver more reliable power supply

Reliability analysis of distribution systems with photovoltaic generation using a power flow simulator and a parallel Monte Carlo approach

This paper presents a Monte Carlo approach for reliability assessment of distribution systems with distributed generation using parallel computing. The calculations are carried out with a royalty-free power flow simulator, OpenDSS (Open Distribution System Simulator). The procedure has been implemented in an environment in which OpenDSS is driven from MATLAB. The test system is an overhead distribution system represented by means of a three-phase model that includes protective devices. The paper details the implemented procedure, which can be applied to systems with or without distributed generation, includes an illustrative case study and summarizes the results derived from the analysis of the test system during one year. The goal is to evaluate the test system performance considering different scenarios with different level of system automation and reconfiguration, and assess the impact that distributed photovoltaic generation can have on that performance. Several reliability indices, including those related to the impact of distributed generation, are obtained for every scenario.Postprint (published version

Solar Enablement Initiative in Australia: Report on Efficiently Identifying Critical Cases for Evaluating the Voltage Impact of Large PV Investment

The increasing quantity of PV generation connected to distribution networks is creating challenges in maintaining and controlling voltages in those distribution networks. Determining the maximum hosting capacity for new PV installations based on the historical data is an essential task for distribution networks. Analyzing all historical data in large distribution networks is impractical. Therefore, this paper focuses on how to time efficiently identify the critical cases for evaluating the voltage impacts of the new large PV applications in medium voltage (MV) distribution networks. A systematic approach is proposed to cluster medium voltage nodes based on electrical adjacency and time blocks. MV nodes are clustered along with the voltage magnitudes and time blocks. Critical cases of each cluster can be used for further power flow study. This method is scalable and can time efficiently identify cases for evaluating PV investment on medium voltage networks