Photovoltaic Penetration Research Articles

Optimal dispatching of distributed photovoltaic system based on operating costs

Abstract This article investigates the method of distributed photovoltaic optimal dispatching method. The goal is to minimize the operating costs of the distribution network system by coordinating electric heating and distributed energy storage when adjusting the demand-side resources of the distribution network. The analysis is conducted on the operating costs of the distribution network system under different penetration rates of photovoltaics to further promote the accommodation capacity of distributed photovoltaics. The research results show that when the penetration rate of photovoltaics is less than or equal to 90%, only electric heating needs to participate in the accommodation capacity of distributed photovoltaics; when the photovoltaic penetration rate exceeds or equals 100%, both distributed energy storage and electric heating need to participate in the accommodation capacity of distributed photovoltaics. As the penetration rate of photovoltaics gradually increases, the total operating costs and purchased electricity costs show a downward trend. When the penetration rate of photovoltaics increases from 70% to 100%, the network loss costs decrease first, but when the penetration rate reaches 110%, photovoltaics cannot be completely integrated, leading to an increase in network loss costs and dispatching costs. This method fully utilizes the flexible adjusting capabilities of electric heating loads and distributed energy storage, promotes the accommodation capacity of distributed photovoltaics, and improves the economic efficiency of distribution network operation.

Transient response of a megawatt-scale solar photovoltaic in an electric distribution utility

There is an increasing trend among customers of an electrical distribution utility to adopt grid-tied solar photovoltaic systems. This shift offers multiple benefits to consumers, including lower monthly electricity bills and a contribution to the development of green energy. For the electrical distribution utility, various impacts may arise due to varying levels of solar energy penetration. This study investigates the effects of integrating varying levels of solar photovoltaic penetration into the commercial consumer network of Cagayan de Oro Electric Power and Light Company (CEPALCO) in the Philippines. Utilizing PowerWorld simulator, the research evaluates 11 different scenarios with solar penetration levels adjusted according to the percentage of load demand. Key findings include alterations in solar megavolt ampere of reactive power output, bus voltage levels, transformer power loading, and transmission line ampacity, with frequency levels remaining stable across scenarios. The optimal solar penetration level was identified at 70%, balancing the benefits of solar energy integration with the need to maintain grid stability and operational limits. This optimal level ensures the effective utilization of renewable energy sources without compromising the performance of CEPALCO’s electrical infrastructure. The research concludes with recommendations for maintaining grid stability and operational limits at the optimal solar penetration limits.

Study of rooftop PV hosting capacity in 20 kV systems in facing distributed generation penetration

---With the increasing request for integrating rooftop photovoltaic (PV) systems into the distribution grid, it is crucial to prevent the potential negative impacts of high PV penetration. Considering the uncertainty and variability characteristics of high rooftop PV penetration, a stochastic approach for determining PV hosting capacity (HC)—the maximum capacity of a PV system to receive electricity from the power distribution network before the network reaches an operating limit violation—is necessary. Therefore, this study proposes calculating PV hosting capacity using the Monte Carlo simulation. Unlike previous works, this paper uses real feeders as case studies, representing both urban and rural areas. The feeder representing an urban area with many industrial and business customers has a higher hosting capacity, 31 % of full load, compared to the feeder representing rural areas, which has 18 % of full load. By using actual feeders that represent urban and rural areas, more representative results for specific problems can be achieved without assuming urban and rural feeders have the same specific problems.

Grid variability and value assessment of long-duration energy storage under rising photovoltaic penetration: Evidence from Japan

Using high-resolution grid power balance and market data, this work investigates the effects of rising solar photovoltaic generation on the variability of large-scale net grid load and spot prices, and conducts an analysis of the potential balancing profits of various grid-scale energy storage systems. Analysis results show the correlation between PV (photovoltaic) generation and electricity demand has been identified as a significant factor influencing spot price value. As PV penetration increases, the value of spot prices experiences a notable decline, with values declining to nearly zero when the share of hourly PV generation surpasses 70 %. The volatility of electricity spot prices has a substantial impact on utilization rates and economic profits of energy storage systems employed for grid energy balancing. Despite the lower roundtrip efficiency, reversible hydrogen storage system can offer positive benefits. The longer storage duration offers the advantage of capturing greater dispatch profits by exploiting price differences over extended periods. Considering the time-varying nature of spot prices, the rated power capacity of the storage system plays a significant role in determining its utilization rates. The larger rated charging and discharging ability of the storage system allows for more effective utilization of price fluctuations, resulting in greater profitability.

Comprehensive Analysis of the Integration and Advanced Control of Photovoltaic Systems for Grid-Connected Applications

In-depth examination of photovoltaic (PV) system integration and enhanced control for grid-connected applications is presented in this study. It examines the difficulties, methods of control, and cutting-edge technologies needed to raise the dependability and effectiveness of PV systems in contemporary power networks. The study explores innovative Maximum Power Point Tracking (MPPT) algorithms, dynamic modeling methodologies, and different adaptive control strategies, emphasizing their importance in PV system performance optimization. It also looks at how high solar PV penetration affects grid stability and talks about creative ways to deal with these issues so that we can have robust and sustainable energy sources in the future. Key Words: photovoltaic Systems, pv integration, pv control strategies, energy storage systems, smart grid technologies, MPPT.

Optimal dispatch strategy of battery energy storage system in utility-scale photovoltaic integrated grid under variability

The frequency response of a photovoltaic (PV) system integrated power grid is severely hampered due to inadequate inertial support. Integrating a battery energy storage system (BESS) can assist in maintaining frequency response by providing a rapid injection of active power into the grid. Nevertheless, instead of typical constant droop settings enabled in BESS, adopting variable PV power dependent operation of BESS can ensure frequency stability with reduced injection, especially in PV-integrated grids. From this viewpoint, this paper proposes a novel frequency control approach of BESS depending on the available PV power in the grid. A gradient descent-based optimization is utilized to evaluate the required maximum injection from the installed BESS to maintain frequency response under different PV generation values. This approach is then tested by modifying the BESS frequency controller to keep the active power dispatch from BESS within the calculated value under a given outage. The whole methodology is analyzed in a customized IEEE 39 bus New England System under different PV penetration and generation scenarios. The results indicate successful convergence to optimal dispatch levels for the BESS across all evaluated scenarios. As PV generation increases, the optimal BESS dispatch as a percentage of rated PV output declines gradually. However, at lower PV generation, this value rises rapidly and reaches the installed BESS capacity. Later, the applicability of the methodology is validated by comparing the simulated outputs with different test grid network and another support technique- Synchronous Condenser (SC). From the standpoint of frequency stability, the proposed technique can assist the grid planners in regulating BESS operations in a renewable integrated grid more effectively.

Kernel-based cumulative sum and differential cumulative sum approaches for resilient fault detection in LVDC microgrids

The energy industry is rapidly shifting from conventional to smart grid systems, involving advancements in microgrids and power management systems. However, achieving desired outcomes with the existing grid setup poses significant challenges. To address the above issues, adopting a Low Voltage Direct Current (LVDC) distribution system provides successful operational advantages. The primary objective of this work is to improve the system's security by developing a more resilient fault detection scheme. The presented work has proposed a Kernel-based Cumulative Sum (K-CUSUM) and Kernel-based Differential Cumulative Sum (K-DCUSUM) technique which is designed to identify changes in data under fewer assumptions. Instead of using the classical Maximum Mean Discrepancy (MMD) technique, the K-CUSUM and K-DCUSUM methods use a non-parametric MMD testing framework to evaluate incoming data by comparing it to reference distribution samples. Further, a comprehensive analysis is undertaken on an LVDC test system, considering fault scenarios involving pole-to-pole and pole-to-ground configurations. This research encompassed the determination of fault location, evaluation of fault resistance, examination of noise introduction, and an exploration of the influence of photovoltaic (PV) penetration. Moreover, the proposed approach is tested for a standard LVDC Microgrid. The results are compared with other contemporary techniques and recent literature.

Design of novel UPFC based damping controller for solar PV integrated power system using arithmetic optimization algorithm

Abstract Integrating renewable energy sources like solar power into traditional power systems poses challenges. One such challenge is the effect of renewable power plants, which use power electronics, on the grid’s stability. Specifically, these plants can impact small-signal stability by either damping or exacerbating low-frequency oscillations. This paper introduces a novel Unified Power Flow Controller (UPFC) based damping controller specifically designed for Solar Photovoltaic (PV) integrated power systems. It employs an Arithmetic Optimization Algorithm (AOA) to optimize the UPFC damping controller parameters and mitigate low-frequency oscillations in the power system. The objective function minimizes the Integral Time Absolute Error (ITAE) of speed deviations under varying loading conditions. The proposed technique is utilized simultaneously to control the modulation index of series and phase angle of shunt converters of UPFC. The MATLAB/simulation results obtained effectively from the proposed technique which is actualized and identify both detrimental and beneficial impacts of increased PV penetration for small signal stability performance. The study reveals both the small-signal stability of the system and its response to large disturbances that alter the active power balance and frequency stability. The results of the analysis demonstrated with single and multimachine environment by comparing with the other optimizations like PSO, DE, DE-PSO and GWO, the proposed one is effective for damping out the oscillations. The effectiveness of the proposed damping controller is further confirmed through real-time validation using the OPAL-RT setup.

Modelling, analysis and forecasting of photovoltaic waste in Malaysia towards sustainable recycling by 2050

Malaysia is currently pushing for greater solar photovoltaic (PV) penetration through various policies, hence need to assess the consequent PV waste situation in preparation for sustainable End-of-Life (EoL) management of the PV systems. Through incorporation of fixed-loss, early-loss, and regular-loss scenarios into Malaysia's PV roadmap, it is projected that 229,009.17 tons to 481,137.12 tons of PV waste would be generated by 2050. Implementing current achievable PV material recovery rates would result in economic value creation between RM 1.02-2.21 billions (USD 213.78-463.92 millions) and carbon emissions avoidance between 398,858.41 tons CO2-eq to 785,712.93 tons CO2-eq by 2050. With crystalline silicon (c-Si) technology contributing more than 60% of waste share, 2029 to 2039 would be the suitable time period to jumpstart recycling operation due to consistent annual c-Si waste input of 8,000 tons/y for financially sustainable recycling. These findings can help garner support for sustainable EoL management of PV waste in Malaysia.

Studying the Optimal Frequency Control Condition for Electric Vehicle Fast Charging Stations as a Dynamic Load Using Reinforcement Learning Algorithms in Different Photovoltaic Penetration Levels

This study investigates the impact of renewable energy penetration on system stability and validates the performance of the (Proportional-Integral-Derivative) PID-(reinforcement learning) RL control technique. Three scenarios were examined: no photovoltaic (PV), 25% PV, and 50% PV, to evaluate the impact of PV penetration on system stability. The results demonstrate that while the absence of renewable energy yields a more stable frequency response, a higher PV penetration (50%) enhances stability in tie-line active power flow between interconnected systems. This shows that an increased PV penetration improves frequency balance and active power flow stability. Additionally, the study evaluates three control scenarios: no control input, PID-(Particle Swarm Optimization) PSO, and PID-RL, to validate the performance of the PID-RL control technique. The findings show that the EV system with PID-RL outperforms the other scenarios in terms of frequency response, tie-line active power response, and frequency difference response. The PID-RL controller significantly enhances the damping of the dominant oscillation mode and restores the stability within the first 4 s—after the disturbance in first second. This leads to an improved stability compared to the EV system with PID-PSO (within 21 s) and without any control input (oscillating more than 30 s). Overall, this research provides the improvement in terms of frequency response, tie-line active power response, and frequency difference response with high renewable energy penetration levels and the research validates the effectiveness of the PID-RL control technique in stabilizing the EV system. These findings can contribute to the development of strategies for integrating renewable energy sources and optimizing control systems, ensuring a more stable and sustainable power grid.

Peak shaving potential and its economic feasibility analysis of V2B mode

Electric vehicles (EVs) as mobile energy-storage devices improve the grid's ability to absorb renewable energy while reducing peak-to-valley load differences. With a focus on smoothing the load curve, this study investigates the peak shaving potential and its economic feasibility analysis of V2B mode. First, based on the virtual microgrid system established in this paper, a Monte Carlo method was used to simulate the driving, charging, and discharging processes of EVs. Second, the effects of the number of charging stations, battery capacity of EVs, and photovoltaic (PV) penetration rate on the peak shaving results were evaluated separately by using the standard deviation of daily loads. Third, the V2B peak shaving strategy and cost composition were explored considering the battery aging costs. Moreover, the economic feasibility and factors influencing the proposed strategy were analyzed. The results indicate that 1) V2B effectively transfers peak power loads between 08:00 h And 20:00 h To low-demand periods at night; 2) as the deployment ratio of charging station increases, the level of load fluctuation decreases significantly. When EV battery capacity is at or above 60 kW h, charging station deployment ratios of 0.43, 0.42, and 0.47 are required for saturated load smoothing in winter, transition period, and summer, respectively; 3) the PV penetration rate for maximizing the collaborative peak shaving capability of V2B and PV power is 30%–40 % and 4) reducing battery costs or extending battery life has the most significant effect on V2B power costs, followed by charging station costs. This study provides a theoretical basis for determining the economic feasibility of charging station planning and provides technical guidance for the rational scheduling of EVs and their friendly interaction with the power grid.

Radiated Electromagnetic Emission from Photovoltaic Systems—Measurement Results: Inverters and Modules

Radiated electromagnetic emission of photovoltaic systems, for example, adversely impacting radiocommunication, can pose a major barrier against further increase in photovoltaic penetration. This is particularly the case near sensitive infrastructure and activities such as hospitals, airports, search and rescue, and military. To understand the impact of each component and installation detail, we performed systematic radiated electromagnetic emission measurements on comparable commercial photovoltaic systems in the frequency range 150 kHz to 30 MHz. Our measurements indicate that string inverters are unlikely to interfere with radiocommunication when installed according to recommended standards, rules, guidelines, and regulations. It was shown that module-level power optimizers are the main cause of high levels of radiated emissions. The frameless bifacial module showed higher levels of radiated emissions than the monofacial module with frame. Changes in cable management and earthing have less impact on radiated emissions than the choice of solar inverter concept and module type.

Hybrid cooperative Markov-based method for decentralized voltage control and loss reduction via photovoltaic reactive power support

The problem of carrying out effective voltage control in distribution grids with significant photovoltaic penetration has received considerable attention in the recent literature. Hence, a variety of methods that leverage PV inverter reactive support capabilities have been proposed for enhancing the grid voltage profile. Despite its great relevance for the utility, active power loss is, quite notably, an often-neglected parameter in such methods. This work proposes a decentralized voltage control method that hybridizes a novel voltage-oriented Cooperative Partially Observable Markov Decision Process model-based control scheme with a heuristic loss minimization approach. To further improve implementation feasibility, a pilot node approach is adopted to drastically reduce the required number of measurements per voltage control zone. The proposed method, named Voltage Control and Loss Reduction Based Cooperative Partially Observable Markov Decision Process, is validated by means of simulation on a 123-bus test system. Results show that, compared to similar methods, it yields a favorable balance between voltage control and loss reduction without the need of real-time multi-objective optimization.

Study of distribution network loss allocation with high photovoltaic penetration ratio

With the rapid development of renewable energy, the penetration ratio of photovoltaic (PV) in the distribution network is getting higher and higher. The fair and reasonable allocation of high loss caused by high PV penetration in the distribution network is of great significance to the healthy development of distribution systems. In order to study the loss allocation in distribution networks with high PV penetration, based on the cooperative game theory, combined with the power flow algorithm, the power flow and loss of the 72-node active distribution network in agricultural and pastoral areas were analyzed. Three scenarios were included: no PV, low PV penetration, and high PV penetration. The allocated loss of the distribution network with high PV penetration and multiple distributed generators was computed. The results show that the loss allocation method, which takes into account the power as well as the network topology, is applicable to distribution networks with multiple distributed generators. In distribution networks with high PV penetration, distributed generators are the main cause of high loss. If the network contains the extreme reverse power flow concerned in this paper, the loss allocated to DGs accounts for more than 95% of the total network power loss.

Voltage Support With PV Inverters in Low-Voltage Distribution Networks: An Overview

Large solar photovoltaic (PV) penetration using inverters in low voltage (LV) distribution networks may pose several challenges, such as reverse power flow and voltage rise situations. These challenges will eventually force grid operators to carry out grid reinforcement to ensure continued safe and reliable operations. However, smart inverters with reactive power control capability enable PV systems to support voltage quality in the distribution network better. This paper gives an overview of the current state-of-the-art control strategies for handling voltage problems through PV inverters and other devices. In addition, the (control) technical issues of PV systems integrated into the LV distribution network are considered from a control point of view. By comparing the control issues of PV integration into the grid, the paper aims to help distribution system operators to expand the volume of PV generation in the distribution system in an efficient and safe manner. Additionally, it will help control engineers and researchers select proper control strategies for PV systems as well as other distributed renewable sources.

Dynamics of large-scale solar PV adoption feedback effects: A technical, economic, and environmental assessment

Large residential solar photovoltaic (PV) penetration has a compound effect on the grid load reductions, PV hosts’ economic savings, and the achievable environmental benefits, which is not fully understood. This study combines process-based energy balance modeling, life cycle assessment, regression analysis, and stochastic demand simulations to assess the technical, economic, and environmental tradeoffs under increased residential solar PV adoption, using Boston, MA as a testbed. It was found that increased PV adoption may lead to a steeper ramp-up in the grid during winter months, but a flattened peak load curve during summer months, emphasizing the need for seasonal time-of-use rates and energy storage. It also reduces electricity wholesale prices, lowering PV hosts' economic benefits by about $15 million under 100 % adoption. The largest buildings present the highest load reduction (top 5.5 %) and environmental benefits (top 16.6 %), but they are the least cost efficient (top 14.5 %), requiring tradeoff balance.

OPTIMAL LOCATION AND SIZING OF DG IN DISTRIBUTION NETWORK: IMPACT ON OVERCURRENT DISTRIBUTION PROTECTION SCHEME

The integration of distributed generation (DG) into the existing distribution networks minimizes active power losses and improves the voltage profile. The recent improvement in the development of DG technology has caused increase in the penetration of DG from different sources. The optimal location and sizing of DG is very challenging and introduces different protection issues. This is caused by penetration of current flow from different source which is contrary to the principles of operation of the conventional overcurrent scheme. This paper presents optimal method of DG placement and sizing using firefly algorithm and its impact of DG penetration on overcurrent protection scheme. Low voltage distribution network is modelled and simulated in PSCAD/EMTDC and DigSilent power factory software using IEEE 33 and Ayepe 34 standard bus. False tripping of feeders, Nuisance tripping, blinding of the protection scheme and unintentional islanding caused as result of Photovoltaic penetration into the distribution network were simulated. Coordination of overcurrent relays with and without DG penetration were analyzed and possible mitigation algorithm were proposed. The simulation result obtained showed that the proposed methods significantly improve the protection scheme coordination..

Malta's low carbon transition towards sustainability

AbstractThe transition to low‐carbon energy and energy independence of a country play an important role in the sustainable development of its energy sector. Another important issue of sustainable energy development is the cost competitiveness in the generation process; with new renewable energy technologies, a sustainable energy transition to carbon‐neutral society is possible. In this article, we present a view of sustainable energy transformation based on a case study of Malta. We have created a simulation of a Maltese electricity system with projected growth and dominance of photovoltaic energy in the electricity market. The study results suggest that a system with a high penetration of photovoltaics has significant advantage over a conventional system using fossil fuels. In particular, in the simulated Maltese system, the total annual cost of energy was reduced threefold, the CO2 emissions were reduced by 40%, and the energy independence of Malta increased by 60%. In the end, the article gives a recommendation for further research into the Maltese energy system.

Advanced Control Strategies for Resilient Voltage and Frequency Regulation in Smart Grids

This study discusses advanced control strategies for voltage and frequency regulation in smart grids, particularly in the integration of renewable energy sources and electrification. These strategies, including Model Predictive Control (MPC), adaptive control, optimal control, robust control, and distributed control, aim to optimize control actions while adhering to system constraints. Case studies show their effectiveness in high photovoltaic penetration, wind power integration, and microgrid operation. However, challenges persist, such as managing uncertainties and coordinating multiple controllers in decentralized power systems. The study acknowledges ongoing research and development in this field, emphasizing the potential for enhancing voltage and frequency regulation in smart grids.

Short-term optimization scheduling method of cascade hydropower and photovoltaic complementary system based on pumping station operation strategy

With the rapid development of photovoltaic power generation, how to improve the photovoltaic grid connection rate is an urgent problem to be solved. This article proposes an optimized scheduling method for the water and photovoltaic complementary system, taking into account the operation strategy of pump stations to improve the photovoltaic grid connection rate. Firstly, a multi-objective optimization scheduling model is constructed to consider both power generation and output fluctuation, and the uncertainty of photovoltaic power generation is analyzed from multiple perspectives. Then, taking the cascade hydropower stations and surrounding photovoltaic power stations in a river basin in Sichuan as an example, the operation strategy of pump stations is introduced into the water and photovoltaic complementary system, considering different weather scenarios, to reduce the photovoltaic curtailment rate. The study verifies that the introduction of pump stations can effectively increase the photovoltaic grid connection rate, and quantitatively analyzes the pump station capacity configuration under different photovoltaic penetration rates.