MITIGATION OF NEGATIVE IMPACTS CAUSED BY ROOF TOP SOLAR PV PENETRATION ON LV FEEDERS

[Virtual Presenter] Good morning everyone! I am very enthusiastic to tell you about the project we are about to talk about today. This project concentrates on finding a solution to reduce the adverse effects caused by the growing installment of rooftop photovoltaic systems on LV feeders. Let us go through the presentation to get more details about the project and what measures we can take to ensure its success..

[Audio] I am presenting a project to you which is of great importance in understanding the serious repercussions of the increasing proliferation of rooftop solar photovoltaic systems on low-voltage feeders. Over the years, due to the advancement in power electronic devices and reduction in the cost of photovoltaic panels, the use of solar plants has grown exponentially and connected to the existing power infrastructure. I have collected some data which shows the growth in solar, wind, biomass, and mini hydro energy in Sri Lanka in the future. As you can see, solar energy in Sri Lanka has a very bright future. However, with the upsurge in renewable energy sources, there is also the possibility of adverse effects on the power grid. Therefore, this project seeks to identify techniques to contain the potential negative consequences of a high penetration of rooftop solar photovoltaic systems on low-voltage feeders..

[Audio] Our project focuses on mitigating the volts-rise caused by the penetration of rooftop solar PV systems on low voltage feeders. Volt-rise occurs when PV generation exceeds demand, resulting in the power flowing back to the LV grids, causing an increase in voltage at the point of common coupling. For this purpose, our project centers around identifying the problem and its potential solutions..

[Audio] This project explores the consequences of the fast expansion of rooftop solar photovoltaic (PV) systems on low voltage (LV) feeders. Our mission is to reduce such adverse effects, as well as to find methods to maximize the use of PV systems, addressing the increasing power demand of our nation. We are establishing and examining the potential difficulties that a high penetration of PV technology may bring to a distinct LV distribution feeder. Besides, we are employing different real and reactive power control approaches to counteract these adverse effects. Eventually, we will present the optimal mitigation technique to the power utility side, in order to better the power quality on all LV lines, for the advantage of the utility and the consumer..

[Audio] The proposed system in this project is Real and Reactive Power Control techniques of Smart PV Inverters. Smart PV inverters are equipped with features like power factor control, leading and lagging power factor control, real and reactive power control, voltage and frequency control, allowing control of power output from the PV system and regulation of power flow in the grid. This project aims to take advantage of the features of Smart PV inverters in order to reduce the damaging effects of rooftop PV penetration on LV feeders..

[Audio] Rooftop solar photovoltaic systems are capable of regulating voltage levels on low voltage feeders through the utilization of a Volt/Var curve. In the event of the voltage exceeding the set upper bound, the system absorbs reactive power; whilst when the terminal voltage drops below the pre-set lower bound, it injects reactive power. This process helps the voltage levels on these feeders remain within the desirable range with increased consistency..

[Audio] The slide is about mitigating the impact of rooftop solar PV systems on LV feeders. One way to do this is by using a Volt-Watt curve. This curve is used to curtail active power output when the voltage goes above or below the permissible voltage bounds. When the voltage exceeds the lower bound and varies between Vvw2 and Vvw3, the active power output is curtailed in accordance with the slope of the curve. Once the voltage reaches the upper voltage bound, the active power output is completely curtailed to ensure that the voltage remains within the permissible limits..

[Audio] We have chosen a low-voltage network with voltage problems caused by the installation of rooftop solar PV systems. To assess the effect of the penetration of PV systems, power flow simulations were done with OPENDSS. The aim is to identify an optimized solution to resolve the network issues by using advanced inverter control strategies..

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[Audio] This slide presents data from a two-feeder-line network comprising 240 customers. It is equipped with a 11KV/415V transformer with a capacity of 160kVA, spanning a total of 1.5 km on the low-voltage (LV) network. The two feeder lines have different numbers of customers and different amounts of installed rooftop solar PV prosumers of 85.01 kWp. Cable types used for the installation include aluminium aerial bundle cables LV244, 3x50+1x16+N35 and 3x70+1x16+N35. This data is necessary to alleviate any potential negative impacts from the penetration of rooftop solar PV systems into the LV feeders..

[Audio] Out of the five scenarios determined for this project, the voltage rise, voltage profile, power flow, and power loss in the feeder will be evaluated in order to assess the impact of each scenario on the LV feeders. These scenarios are defined by the level of penetration and capacity of solar customers, as well as cumulative solar capacity in kilowatts..

[Audio] We analysed the fluctuation of phase voltage at three points on Feeder 1 - the Feeder Head, the middle of the Feeder, and the Feeder End - throughout the day to gain an understanding of the effects of rooftop solar PV systems on low-voltage power supply lines, referred to as 'LV feeders'. The figure in front of us displays the voltage variation along the line under a situation where PV generation is at 0%, thought of as the standard condition..

[Audio] The figure indicates that when the solar penetration reaches 100%, an overvoltage condition occurs at the feeder end, beyond the upper voltage limit. Fortunately, we have the advantage that the transformer maximum capacity can handle a solar penetration of up to 100%, thus avoiding any more overvoltage conditions on the feeder. This project seeks to find ways to deal with the negative effects brought about by the mass installation of rooftop solar PV systems on low voltage feeders..

[Audio] We can observe from this slide that once rooftop solar PV systems are put in place, voltage is likely to be above the upper limit of 1.06 p.u. at the end of the feeder. Nevertheless, this won't occur everywhere along the feeder. This project focuses on diminishing the drawbacks that come from this circumstance..

[Audio] This project is a response to the issue of solar PV penetration on LV feeders. As the level of penetration increases, so does the risk of reverse power flow. We have observed a reverse power flow of 43kW at 100% of the solar PV penetration level. This project aims to reduce the risk of this reverse power flow and reduce the potential negative impacts it can cause..

[Audio] "It is now well established that the integration of rooftop solar PV systems on LV feeders can have a significant impact on the power loss. Our project has shown that active and reactive power loss are seen to be reduced up to 80% of the penetration level. However, beyond that power loss increase compared to no solar PV. This means that there are limits to how much rooftop solar PV can be integrated onto LV feeders without undue negative impacts on power loss. The implications of this are important for the design of our power grid in the future.”.

[Audio] Focus of Slide 17 is on the smart inverter technology which assists in managing the rooftop solar PV system. The smart inverter acts as a bridge between the PV panel and the grid. It takes into consideration various inputs like power factor, irradiance, temperature, voltage, and power efficiency, along with measuring voltage, active power, reactive power, and apparent power. This assists in keeping the quality and safety of the grid intact, while simultaneously improving the efficiency of the solar PV system..

Parameter Settings of smart PV Inverters.

[Audio] We employed three control techniques for the project to reduce voltage threshold breaks that were observed when a great amount of rooftop solar PV systems were connected to a low voltage (LV) feeder. By implementing these techniques, we were able to increase active power generation and prevent overvoltage issues. Simulation results revealed the three control techniques were effective in preventing voltage limit violations, enabling us to fend off the problem of overvoltage created by the integration of rooftop solar PV systems on LV feeders..

[Audio] The figure shows that when the transformer capacity for rooftop solar PV systems reaches 100%, a voltage violation occurs. However, if smart inverter control strategies are employed, this can reduce the overvoltage to an acceptable level..

[Audio] This slide's figure demonstrates that the Volt-Watt control technique can significantly cut the active power of a rooftop solar PV system to 48.84%, in comparison to a 25.85% active power reduction that the Fixed PF technique produces, with a maximum power production of 43 kW. This project attempts to minimize the adverse impacts that this system can have on low voltage feeders..

[Audio] This project seeks to reduce the adverse effects of rooftop solar PV systems on low voltage feeders. Simulation results show that Volt-Var control is the most effective in managing reactive power absorption, reaching a maximum of 31kVAr. In contrast, Volt-Watt control did not provide any assistance to the system..

[Audio] Penetration of rooftop solar PV systems on Low Voltage feeders can cause marked effects on Power loss, as evident in the figures. It is discernible that two Volt-Var strategies have significantly more Active and Reactive loss than the other control scenarios. This is a consequence of reactive power passing over a long distance with low X/R ratio, resulting in the reactive power absorption taking place far from the distribution transformer..

[Audio] The figures showed that the Volt-Watt control technique was the most successful in lowering both active and reactive power losses in comparison to other scenarios. It was the only method that not only achieved a reduction in active power, but also eliminated the absorption of reactive power - a crucial factor in preventing the LV feeders from suffering the detrimental effects of rooftop solar PV systems..

Simulated results for the comparative analysis using control techniques of solar PV inverters.

[Audio] The slide includes a chart outlining the measurements taken to analyze the impact of rooftop solar PV systems on low voltage feeders. It shows active power and reactive power in kilowatts and kilovolt amps respectively. Additionally, it shows fixed power factor, Volt/Var VV1, Volt/Var VV2, and Volt/Watt. This data was collected to investigate the possible effect of incorporating such systems into a power network..

[Audio] This slide focuses on the effects of the penetration of rooftop solar PV systems on low voltage feeders. Although a voltage rise can be caused by solar PV, Watt and Var control may not be necessary due to the limited voltage rise. Watt control is more effective when using low X/R Conductors. We will further examine the feeder segmentation which includes the front segment, the middle segment, and the end segment featuring PV and the PV Substation..

[Audio] Presenting the results of a detailed study of an urban Low Voltage (LV) distribution network, it was discovered that high penetration of solar PV can lead to various problems - such as voltage rise, reverse power flow, and power losses - when analyzed through OPENDSS and PYTHON software. Three power control strategies of solar PV inverters to tackle the overvoltage issue were presented and evaluated, with Volt-Watt control being found to be the most optimal technique for LV feeders with low X/R ratio in order to provide efficient voltage control and maximize the PV hosting capacity, while having minimal impact on customers..

[Audio] This project examines ways to reduce the effects of introducing rooftop solar PV systems to low-voltage power networks. We will analyse research in Indonesia, Sri Lanka and Saudi Arabia, as well as consider the potential of the Sri Lankan “Battle of Solar Programme”. Additionally, we will investigate the concept of smart inverters and volt/var control. We will also examine OpenDSS and the time series video tutorials, as well as the OpenDSS manual provided by EPRI. This project is a significant step in reducing the effect of high penetration of rooftop solar PV systems on low voltage feeders..

[Audio] We have come to the end of this presentation and I'd like to remind you of the importance of this project. The aim of this project is to reduce the negative impacts caused by the penetration of rooftop solar PV systems on LV feeders. Solar power is a renewable energy source that should be embraced; however, we need to ensure that potential risks are mitigated. Your attention is greatly appreciated. Thank you..