Penetration Level Of Photovoltaic Systems Research Articles

Maximize the penetration level of photovoltaic systems and shunt capacitors in distribution systems for reducing active power loss and eliminating conventional power source

In this paper, photovoltaic systems and shunt capacitors are optimally placed in three IEEE distribution systems. Moth swarm algorithm, Equilibrium optimization and Coot optimization algorithm are used to find the numbers, locations and sizes of the added electric components so that total active power loss is minimum and all constraints are satisfied. As reaching optimal solutions, voltage of nodes and current of conductors satisfy operating ranges while all added photovoltaic systems and all shunt capacitors respectively supply enough active and reactive power demands to loads. Among the three applied algorithms, Moth swarm algorithm is more complicated but it is much more effective than two others. In fact, it can reach less active power loss by 76.3% as compared to others and by 86.52%, 83.3% and 94.48% as compared to base systems. Thus, it concludes that the placement of photovoltaic systems and shunt capacitors can replace the conventional power source and Moth swarm algorithm is an effective approach in optimizing the placement of both photovoltaic systems and shunt capacitors.

Real-Time Constant Power Generation Method for PV Systems With Low Tracking Error

In this paper, a new constant power generation (CPG) method for photovoltaic (PV) systems is proposed to mitigate the power variations due to changes in external conditions. A power grid with the high penetration of renewables might face both voltage and frequency instability when the power variations from PV systems are large. The proposed CPG method estimates the constant power point (CPP) in real-time without requiring the time step used in the conventional methods. Thus, it can rapidly track the CPP, and it is able to generate the constant power effectively even for sudden changes in external conditions. The practical effectiveness of proposed CPG method is verified by experimental and hardware-in-the-loop tests. The results clearly show that the proposed CPG method provides a much faster response with a less tracking error than the conventional methods in different operating conditions. Thus, it can be an effective solution to further increase the penetration level of PV systems to power grid.

Optimal Determination of Photovoltaic Penetration Level Considering Protection Coordination

Photovoltaic (PV) systems have been gaining popularity among distribution network engineers. The integration of these small-scale sources has a variety of benefits for the distribution network. One of the most important benefits is the power loss reduction. However, a high penetration level of PV systems may disrupt the protection coordination of conventional overcurrent relays of the distribution network, reducing the profit of the electricity distribution company (EDC) due to healthy feeder de-energization. This paper determines the optimal penetration level of PV systems in the distribution network considering both power loss reduction profit and protection miscoordination cost to maximize the profit of the EDC. The merits of the proposed methodology are verified through several case studies on a simulation model of the IEEE 33-bus test system in the Electrical Transient Analyzer Program (ETAP) environment considering the reliability data of the IEEE Roy Billinton Test System.

Fault Identification of Photovoltaic Array Based on Machine Learning Classifiers

Fault identification in Photovoltaic (PV) array is a contemporary research topic motivated by the higher penetration levels of PV systems in recent electrical grids. Therefore, this work aims to define an optimal Machine learning (ML) structure of automatic detection and diagnosis algorithm for common PV array faults, namely, permanent (Arc Fault, Line-to-Line, Maximum Power Point Tracking unit failure, and Open-Circuit faults), and temporary (Shading) under a wide range of climate datasets, fault impedances, and shading scenarios. To achieve the best-fit ML structure, three distinct ML classifiers are compared, namely, Decision Tree (DT) based on different splitting criteria, K-Nearest Neighbors (KNN) based on the different metrics of distance and weighting functions, and Support Vector Machine (SVM) based on different Kernel functions and multi-classification approaches. Also, Bayesian Optimization is adopted to assign the optimal hyperparameters to the fault classifiers. To investigate the performance of classifiers reported, both simulation and experimental case studies are carried out and presented.

A Novel Integrated Profit Maximization Model for Retailers under Varied Penetration Levels of Photovoltaic Systems

In contemporary energy markets, the Retailer acts as the intermediate between the generation and demand sectors. The scope of the Retailer is to maximize its profits by selecting the appropriate procurement mechanism and selling price to the consumers. The wholesale market operation influences the profits since the mix of generation plants determines the system marginal price (SMP). In the related literature, the SMP is treated as a stochastic variable, and the wholesale market conditions are not taken into account. The present paper presents a novel methodology that aims at connecting the wholesale and retail market operations from a Retailer’s perspective. A wholesale market clearing problem is formulated and solved. The scope is to examine how different photovoltaics (PV) penetration levels in the generation side influences the profits of the Retailer and the selling prices to the consumers. The resulting SMPs are used as inputs in a retailer profit maximization problem. This approach allows the Retailer to minimize economic risks and maximize profits. The results indicate that different PV implementation levels on the generation side highly influences the profits and the selling prices.

Impact of harmonic limits on PV penetration levels in unbalanced distribution networks considering load and irradiance uncertainty

Photovoltaic (PV) system is one of the most important technologies among the renewable energy resources. With the increasing penetration of PV systems in distribution networks, harmonic distortions also rise due to the inevitable effects of PV inverters. Therefore, determination of the optimal PV penetration level is a vital issue in terms of preventing power quality problems. In this paper, probabilistic and deterministic approaches are proposed to determine the optimal penetration levels of PV systems in unbalanced distorted distribution networks by taking into account the uncertainty of load profile and the intermittent characteristic of PV system output power due to changes in solar irradiance. The Interior Point (IP) method is applied to solve the optimization problem in conjunction with the Monte Carlo Simulation (MCS) and K – means clustering, respectively. The methodology is based on the dependence of the harmonic spectrum of PV injected current on solar irradiance. The harmonic power quality parameters are calculated by using loop frame of reference based three phase harmonic power flow method in the unbalanced distribution network, where the nonlinear loads and PV systems are interfaced. The allowable PV penetration levels are determined based on power quality parameters comprising of total harmonic voltage and individual harmonic voltage distortions, and RMS bus voltage limits.

Availability, Performance and Reliability Evaluation for PV Distributed Generation

Nowadays, renewable energy resources play an important role in replacing conventional energy resources such as fossil fuel by integrating solar, wind and geothermal energy. Photovoltaic energy is one of the very promising renewable energy resources which grew rapidly in the past few years, it can be used to produce electric energy through photovoltaic process. The primary objective of the research proposed in this paper is to facilitate the increasing penetration levels of PV systems in the electric distribution networks. In this work, the PV module electrical model is presented based on the mathematical equations and was implemented on MATLAB to simulate the non-linear characteristics I-V and P-V curves with variable input parameters which are irradiance and temperature based on Riyadh region. In addition, the reliability evaluation of distribution networks, including distributed generators of solar photovoltaic (PV) with varying output power capacity is presented also. The Monte Carlo simulation algorithm is applied to test the distribution network which is RBTS Bus 2 and the same has been conducted on the original case of distribution network substation 7029 which is located at KSA Riyadh. The two distribution networks have been modified to include the PV’s distributed generators. The distributed generators contribute to supply a part of the load during normal mode and supply the entire load during component failure or failure of grid operation supply. The PV stochastic models have been used to simulate the randomness of these resources. Moreover, the study shows that the implementation and integration of renewable resources as distributed generations have improved the reliability of the distribution networks.

Effects of Mutual Coupling and Transposition of Phase Conductors on the Maximum Photovoltaic Penetration Levels in Distribution Feeders

The penetration level of solar photovoltaic (PV) generation in a distribution system is often limited by the constraint on voltage variation due to large intermittent power injection. This paper investigates the penetration levels of PV systems in distribution feeders by taking into account the mutual coupling effect between phase conductors. The equivalent circuit models for distribution line segments, including the grounding effect and the mutual coupling between phase conductors and the grounded neutral line, are applied to computer simulation. Two practical Taipower distribution feeders are selected for system analysis to study the maximum PV penetration with the proposed precise modeling of the feeder network. The increase of allowable PV penetration by executing the transposition of phase conductors to improve the three-phase balance is also analyzed.

A Hybrid Power Control Concept for PV Inverters With Reduced Thermal Loading

This letter proposes a hybrid power control concept for grid-connected photovoltaic (PV) inverters. The control strategy is based on either a maximum power point tracking control or a constant power generation (CPG) control depending on the instantaneous available power from the PV panels. The essence of the proposed concept lies in the selection of an appropriate power limit for the CPG control to achieve an improved thermal performance and an increased utilization factor of PV inverters, and thus, to cater for a higher penetration level of PV systems with intermittent nature. A case study on a single-phase PV inverter under yearly operation is presented with analyses of the thermal loading, lifetime, and annual energy yield. It has revealed the trade-off factors to select the power limit and also verified the feasibility and the effectiveness of the proposed control concept.

Low-Voltage Ride-Through of Single-Phase Transformerless Photovoltaic Inverters

Transformerless photovoltaic (PV) inverters are going to be more widely adopted in order to achieve high efficiency, as the penetration level of PV systems is continuously booming. However, problems may arise in highly PV-integrated distribution systems. For example, a sudden stoppage of all PV systems due to anti-islanding protection may contribute to grid disturbances. Thus, standards featuring with ancillary services for the next-generation PV systems are under a revision in some countries. The future PV systems have to provide a full range of services as what the conventional power plants do, e.g., low-voltage ride-through (LVRT) under grid faults and grid support service. In order to map future challenges, the LVRT capability of three mainstream single-phase transformerless PV inverters under grid faults is explored in this paper. Control strategies with reactive power injection are also discussed. The selected inverters are the full-bridge (FB) inverter with bipolar modulation, the FB inverter with dc bypass, and the Highly Efficient and Reliable Inverter Concept (HERIC). A 1-kW single-phase grid-connected PV system is analyzed to verify the discussions. The tests confirmed that, although the HERIC inverter is the best candidate in terms of efficiency, it is not very particularly feasible in case of a voltage sag. The other two topologies are capable of providing reactive current during LVRT. A benchmarking of those inverters is also provided in this paper, which offers the possibility to select appropriate devices and to further optimize the transformerless system.

Modeling and Field Measurements of Photovoltaic Units Connected to LV Grid. Study of Penetration Scenarios

The operation of photovoltaic (PV) units connected to the grid is characterized by several uncertainties due to the number of currently operating units, the points where these units are sited, the exported power, and the injection of harmonic currents. The objective of this paper is to investigate the impact of the penetration of PV units in the low-voltage (LV) network. Thus, a model has been developed for the computation of load flows, harmonics, and voltages in the feeders. A PV panel is modeled as an irradiance-driven current generator, with an embodied maximum power point (MPP) tracking algorithm; it is connected to the network via electronic switches that represent the PV inverter. Simulations are performed with PSIM and Harmoniques simulator packages. Results from the simulated model are validated with data acquired from field measurements and bibliography. Finally, the acceptable penetration level of PV systems is investigated for several scenarios, depending on the topology of the LV network, the number, size, and locations of loads and PV units.