scholarly journals Voltage Reduction in Medium Voltage Distribution Systems Using Constant Power Factor Control of PV PCS

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5430
Author(s):  
Daisuke Iioka ◽  
Takahiro Fujii ◽  
Toshio Tanaka ◽  
Tsuyoshi Harimoto ◽  
Junpei Motoyama
Keyword(s):  
Power Factor ◽  
Distribution System ◽  
Power Flow ◽  
Distribution Systems ◽  
Low Voltage ◽  
Voltage Distribution ◽  
Constant Power ◽  
Voltage Rise ◽  
Pv Systems ◽  
Power Factor Control

Reverse power flow from a photovoltaic (PV) system in a distribution system causes a voltage rise. A relative study regarding the reduction in the distribution feeder voltage depending on system conditions and the magnitude of reverse power flow has been conducted. Several methods for mitigating voltage rise have been proposed; however, the influence of these methods on the voltage in the distribution system, where the voltage is reduced due to reverse power flow, remains to be determined. In this study, the effect of constant power factor control in low-voltage PV systems, which are widely used as voltage rise countermeasures in distribution systems, was analyzed under the condition that the distribution line voltage decreases due to reverse power flow. Consequently, the constant power factor control of the low-voltage distribution system was found to adversely reduce voltage in the medium voltage distribution system due to the consumption of lagging reactive power by the PV systems.

scholarly journals Analysis of Voltage Unbalance and Energy Loss in Residential Low Voltage Distribution Systems with Rooftop Photovoltaic Systems

2020 ◽  
Vol 190 ◽  
pp. 00033
Author(s):  
Rattanaprapa Charoenwattana ◽  
Umarin Sangpanich
Keyword(s):  
Energy Loss ◽  
Distribution Systems ◽  
Low Voltage ◽  
Energy Losses ◽  
Photovoltaic Systems ◽  
Housing Estate ◽  
Voltage Distribution ◽  
Pv System ◽  
Voltage Unbalance ◽  
Pv Systems

This paper investigates effects of voltage unbalance and energy losses due to the connection of rooftop photovoltaic systems in a low voltage distribution system of a housing estate, which has light loads during daytime. The paper presents a case study of a real distribution power system of housing estate in Thailand. Voltage unbalance and energy losses were simulated by using system characteristic and load data from GIS database of PEA with the DIgSILENT Power Factory program. The key findings of our analysis are as follows. Firstly, the number of installable 1-phase rooftop PV systems varies directly with load density. Secondly, the number of installed 1-phase rooftop PV systems can be increased if the installation locations are closer to the transformer. For 3-phase rooftop PV systems, their installations do not have any effects on the voltage unbalance. Furthermore, system energy loss relates to the load density and PV system installation locations in the same way as the voltage unbalance. The key implication of our study is that the installation of 1-phase rooftop PV system should be granted based on a careful consideration of the installation location and the load density.

scholarly journals On the Conflict between LVRT and Line Protection in LV Distribution Systems with PVs: A Current-Limitation-Based Solution

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2909 ◽  
Author(s):  
Aristotelis Tsimtsios ◽  
Dionisis Voglitsis ◽  
Ioannis Perpinias ◽  
Christos Korkas ◽  
Nick Papanikolaou
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Low Voltage ◽  
Energy Resource ◽  
Distribution Networks ◽  
Voltage Distribution ◽  
Current Limitation ◽  
Protection Scheme ◽  
Low Voltage Ride Through ◽  
Photovoltaic Generators

The upcoming adoption of low-voltage-ride-through requirements in low-voltage distribution systems is expected to raise significant challenges in the operation of grid-tied inverters. Typically, these inverters interconnect photovoltaic units, which are the predominant distributed energy resource in low-voltage distribution networks, under an umbrella of standards and protection schemes. As such, a challenging issue that should be considered in low-voltage distribution network applications, regards the coordination between the line protection scheme (typically consisting of a non-settable fuse) and the low-voltage-ride-through operation of photovoltaic generators. During a fault, the fuse protecting a low-voltage feeder may melt, letting the generator to continue its ride-through operation. Considering that the efficacy/speed of the anti-islanding detection is affected by ride-through requirements, this situation can lead to protracted energization of the isolated feeder after fuse melting (unintentional islanding). To address this issue, this paper proposes a fault-current-limitation based solution, which does not require any modification in the existing protection scheme. The operation principles, design, and implementation of this solution are presented, while, its effectiveness is supported by extensive simulations in a test-case low-voltage distribution system. A discussion on the presented results concludes the paper.

scholarly journals An Innovative Operation Strategy of ESS for Capacity Expansion of Renewable Energy and Customer Load with Electric Vehicle Chargers in Low Voltage Distribution Systems

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4668
Author(s):  
Kyung-Sang Ryu ◽  
Dae-Jin Kim ◽  
Yang-Hyun Nam ◽  
Heesang Ko ◽  
Byungki Kim ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Electric Vehicle ◽  
Distribution System ◽  
Distribution Systems ◽  
Low Voltage ◽  
Energy Resource ◽  
Operation Strategy ◽  
Voltage Distribution ◽  
Allowable Limit ◽  
Bidirectional Power Flow

This paper proposes an innovative operation strategy to extend the acceptance of EVC (Electric Vehicle Charger) and RES (Renewable Energy Resource) in LVDS (Low Voltage Distribution System) by introducing an ESS (Energy Storage System). In conventional LVDS, the load and RES capacity are designed not to exceed the pole transformer capacity. However, when the ESS is connected to the end of LVDS and the bidirectional power flow becomes possible, the linkable capacity of the load and renewable energy can be improved up to twice the capacity of the pole transformer. In addition, even though the power consumption of the load and the power generation of RES exceed the pole transformer capacity, it is possible to maintain the feeder capacity and grid voltage within the allowable limit by the appropriate operation of the ESS. The simulations are performed in the environment of PSCAD/EMTDC, and the ability of the proposed strategy is assessed and discussed.

scholarly journals Energy Efficiency Study for the Distribution System Using Low Voltage Transformer Under Harmonic Conditions

2021 ◽  
Author(s):  
Bruno M. Laurindo ◽  
Felipe Marins ◽  
Bruno Wanderley França ◽  
Marcio Zamboti Fortes ◽  
Mauricio Aredes
Keyword(s):  
Power Distribution ◽  
Distribution System ◽  
Power Flow ◽  
Distribution Systems ◽  
Low Voltage ◽  
Energy Losses ◽  
Nonlinear Loads ◽  
Voltage Transformer ◽  
Operation Temperature ◽  
Three Phase

In Brazil, technical energy losses in power distribution systems are determined by power flow studies considering medium and low voltage systems, according to ANEEL recommendations, presented in PRODIST Module 7. These technical losses occur due to physical phenomena and are intrinsically associated with the energy distribution process. However, standards currently do not consider energy losses from harmonic components generated by nonlinear loads, which represent almost all the loads present in electrical systems worldwide. Thus, this paper aims to analyze the operation of a low voltage transformer under harmonic current conditions and to evaluate not only the operation temperature of the equipment, but also to verify the energy losses in it. This test is performed on a laboratory platform and the results are experimental using an adjustable three-phase source and a 3kVA three-phase transformer.

scholarly journals A Modification of Newton–Raphson Power Flow for Using in LV Distribution System

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7600
Author(s):  
Anuwat Chanhome ◽  
Surachai Chaitusaney
Keyword(s):  
Distribution System ◽  
Power Flow ◽  
Quadratic Convergence ◽  
Low Voltage ◽  
Load Flow ◽  
Voltage Distribution ◽  
Convergence Properties ◽  
Branch Model ◽  
Power Injection ◽  
Newton Raphson

The Newton–Raphson (NR) method is still frequently applied for computing load flow (LF) due to its precision and quadratic convergence properties. To compute LF in a low voltage distribution system (LVDS) with unbalanced topologies, each branch model in the LVDS can be simplified by defining the neutral and ground voltages as zero and then using Kron’s reduction to transform into a 3 × 3 branch matrix, but this decreases accuracy. Therefore, this paper proposes a modified branch model that is also reduced into a 3 × 3 matrix but is derived from the impedances of the phase-A, -B, -C, neutral, and ground conductors together with the grounding resistances, thereby increasing the accuracy. Moreover, this paper proposes improved LF equations for unbalanced LVDS with both PQ and PV nodes. The improved LF equations are based on the polar-form power injection approach. The simulation results show the effectiveness of the modified branch model and the improved LF equations.

scholarly journals Comparison of Reactive Power Control Techniques for Solar PV Inverters to Mitigate Voltage Rise in Low-Voltage Grids

Electronics ◽  
2021 ◽  
Vol 10 (13) ◽  
pp. 1569
Author(s):  
Dilini Almeida ◽  
Jagadeesh Pasupuleti ◽  
Janaka Ekanayake
Keyword(s):  
Power Control ◽  
Power Factor ◽  
Power Flow ◽  
Reactive Power ◽  
Low Voltage ◽  
Voltage Regulation ◽  
Solar Pv ◽  
Reactive Power Control ◽  
Control Techniques ◽  
Power Factor Control

The greater integration of solar photovoltaic (PV) systems into low-voltage (LV) distribution networks has posed new challenges for the operation of power systems. The violation of voltage limits attributed to reverse power flow has been recognized as one of the significant consequences of high PV penetration. Thus, the reactive power control of PV inverters has emerged as a viable solution for localized voltage regulation. This paper presents a detailed study on a typical Malaysian LV distribution network to demonstrate the effectiveness of different reactive power control techniques in mitigating overvoltage issues due to high PV integration. The performance of four reactive power control techniques namely, fixed power factor control, scheduled power factor control, power factor control as a function of injected active power, and voltage-dependent reactive power control were analyzed and compared in terms of the number of customers with voltage violations, reactive power compensation, and network losses. Three-phase, time-series, high-resolution power-flow simulations were performed to investigate the potential overvoltage issues and to assess the performance of the adoption of reactive power controls in the network. The simulation results revealed that the incorporation of reactive power controls of solar PV inverters aids in successfully mitigating the overvoltage issues of typical Malaysian networks. In particular, the Volt-Var control outperformed the other control techniques by providing effective voltage regulation while requiring less reactive power compensation. Furthermore, the comparative analysis highlighted the significance of employing the most appropriate control technique for improved network performance.

scholarly journals The Concept of Dynamic Hosting Capacity for Distributed Energy Resources: Analytics and Practical Considerations

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2576 ◽  
Author(s):  
Tiago Elias Castelo de Oliveira ◽  
Math Bollen ◽  
Paulo Fernando Ribeiro ◽  
Pedro M. S. de Carvalho ◽  
Antônio C. Zambroni ◽  
...  
Keyword(s):  
Distribution System ◽  
Power Flow ◽  
Distribution Systems ◽  
Low Voltage ◽  
Photovoltaic System ◽  
Communication Tool ◽  
Performance Limits ◽  
Power Performance ◽  
Electrical Distribution Systems ◽  
General Aspects

The hosting capacity approach is presented as a planning, improving, and communication tool for electrical distribution systems operating under specific uncertainties, such as power quality issues, power stabilities, and reliability, among others. In other words, it is an important technique, when renewable sources are present, to answer the amount of power that is possible to supply to the system without trespassing power performance limits. However, the power flow in a distribution system, for instance, can change throughout time due to the penetration of distributed generation, as well as load consumption. Based on the dynamic nature existing in distribution grids nowadays, it is important to highlight that the hosting capacity should not be calculated in a specifically chosen time only, but must be analyzed throughout a period of time. Thus, this paper introduces an extended concept of hosting capacity in relation to an integrated impact of harmonic voltage distortion and voltage rise as a function of time for daily, weekly, monthly, or even yearly periods. This extended concept is named as Dynamic Hosting Capacity (DHC(t)). General aspects of DHC(t) are demonstrated via measured data on a photovoltaic system (PV) connected at a low-voltage (LV) side of a university building.

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