scholarly journals Improvement of Voltage Unbalance by Current Injection Based on Unbalanced Line Impedance in Distribution Network with PV System

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 8126
Author(s):  
Daisuke Iioka ◽  
Takahiro Fujii ◽  
Toshio Tanaka ◽  
Tsuyoshi Harimoto ◽  
Junpei Motoyama ◽  
...  
Keyword(s):  
Power Flow ◽  
Large Scale ◽  
Distribution Network ◽  
Current Injection ◽  
Pv System ◽  
Line Voltage ◽  
Voltage Unbalance ◽  
Current Unbalance ◽  
The Relationship ◽  
A Current

In this study, we have proposed a novel current injection determination method that improves the voltage unbalance based on the unbalanced line impedance in a distribution network with a large-capacity PV system. An increase in the unbalance of the distribution line voltage was observed owing to a large-scale reverse power flow. To visualize this phenomenon, the P-V curves were derived for each phase to indicate the increase in the voltage unbalance with respect to the reverse power flow. Based on the derived P-V curves, the effect of a current unbalance on the voltage unbalance was investigated. It was clarified that there is a current unbalance that can improve the voltage unbalance even if the line impedance is unbalanced. In other words, the current unbalance that can theoretically make the voltage unbalance zero could be expressed in terms of the symmetrical components of unbalanced line impedance. As an application of the proposed method, the effect of the mitigation of voltage unbalance was demonstrated by controlling single-phase reactors, whose numbers were determined by using the relationship between the unbalanced line current and unbalanced line impedance.

scholarly journals Impact of Inverter Controller-Based Grid-Connected PV System in the Power Quality

2020 ◽  
pp. 462-469
Author(s):  
Ali Q. Al-Shetwi ◽  
◽  
Muhamad Zahim Sujod ◽  
M. A. Hannan ◽  
Majid A. Abdullahd ◽  
...  
Keyword(s):  
Power Quality ◽  
Large Scale ◽  
Controller Design ◽  
Vital Role ◽  
Photovoltaic System ◽  
Voltage Source ◽  
Pv System ◽  
Voltage Unbalance ◽  
A Current

In a Grid-Connected Photovoltaic System (GCPS), the inverters are applied for integration with the power grid. This integration brings some issues at the connection point. Therefore, grid-tied inverter control performs a vital role in feeding the power system with good power quality. This study presents a current-controlled Voltage Source Inverter (VSI) strategy for large-scale GCPS generates 1000 kW rated of power. The methodology and structure of the control system are presented. The power quality issues such as harmonics, voltage fluctuation, voltage unbalance, and power factor are limited at the interfacing point into the required limits as imposed by the standards. This study also discusses the controller design and the simulation results are introduced to show its effectiveness. Furthermore, the values obtained may be used to evaluate the power supply quality of various inverter controllers.

Fast Service Restoration of Multi-Source Active Distribution Network with Microgrids and Electric Vehicles

2014 ◽  
Vol 672-674 ◽  
pp. 1175-1178
Author(s):  
Guang Min Fan ◽  
Ling Xu Guo ◽  
Wei Liang ◽  
Hong Tao Qie
Keyword(s):  
Electric Vehicles ◽  
Distribution System ◽  
Power Flow ◽  
Optimal Power Flow ◽  
Large Scale ◽  
Distribution Network ◽  
Active Distribution Network ◽  
Optimal Power ◽  
Service Restoration ◽  
Restoration Method

The increasingly serious energy crisis and environmental pollution problems promote the large-scale application of microgrids (MGs) and electric vehicles (EVs). As the main carrier of MGs and EVs, distribution network is gradually presenting multi-source and active characteristics. A fast service restoration method of multi-source active distribution network with MGs and EVs is proposed in this paper for service restoration of distribution network, which takes effectiveness, rapidity, economy and reliability into consideration. Then, different optimal power flow (OPF) models for the service restoration strategy are constructed separately to minimize the network loss after service restoration. In addition, a genetic algorithm was introduced to solve the OPF model. The analysis of the service restoration strategy is carried out on an IEEE distribution system with three-feeder and eighteen nodes containing MGs and EVs, and the feasibility and effectiveness are verified

scholarly journals The Technical Challenges Facing the Integration of Small-Scale and Large-scale PV Systems into the Grid: A Critical Review

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1443 ◽  
Author(s):  
Abdullah Alshahrani ◽  
Siddig Omer ◽  
Yuehong Su ◽  
Elamin Mohamed ◽  
Saleh Alotaibi
Keyword(s):  
Large Scale ◽  
Distribution Network ◽  
Small Scale ◽  
Energy Access ◽  
Solar Pv ◽  
Pv System ◽  
Pv Systems ◽  
Technical Challenges ◽  
Technical Solutions ◽  
The Impact

Decarbonisation, energy security and expanding energy access are the main driving forces behind the worldwide increasing attention in renewable energy. This paper focuses on the solar photovoltaic (PV) technology because, currently, it has the most attention in the energy sector due to the sharp drop in the solar PV system cost, which was one of the main barriers of PV large-scale deployment. Firstly, this paper extensively reviews the technical challenges, potential technical solutions and the research carried out in integrating high shares of small-scale PV systems into the distribution network of the grid in order to give a clearer picture of the impact since most of the PV systems installations were at small scales and connected into the distribution network. The paper reviews the localised technical challenges, grid stability challenges and technical solutions on integrating large-scale PV systems into the transmission network of the grid. In addition, the current practices for managing the variability of large-scale PV systems by the grid operators are discussed. Finally, this paper concludes by summarising the critical technical aspects facing the integration of the PV system depending on their size into the grid, in which it provides a strong point of reference and a useful framework for the researchers planning to exploit this field further on.

scholarly journals The Influence of Decentralized Wind Power on the Characteristics of Distribution Network

2021 ◽  
Vol 261 ◽  
pp. 01037
Author(s):  
Ruomeng Jiang
Keyword(s):  
Wind Power ◽  
Power Flow ◽  
Large Scale ◽  
Power Grid ◽  
Distribution Network ◽  
Flow Distribution ◽  
Voltage Level ◽  
Negative Impacts ◽  
The Impact ◽  
Planning And Operation

This paper expounds the influence of decentralized wind power on the characteristics of distribution network. Through analysis, it can be concluded that after installing an appropriate amount of decentralized wind power, the voltage level of load bus can be improved. The power flow distribution will be changed, and the network loss of the power grid will be reduced. The decentralized wind power has also brought about negative impacts, such as voltage flicker and harmonics, the impact on the scope and direction of protection of relay protection, and greater uncertainty in the planning and operation of regional power grid. The analysis above provides some theoretical guidance for the large-scale development of decentralized wind power in the future.

scholarly journals Management of Voltage Profile and Power Loss Minimization in a Grid-Connected Microgrid System Using Fuzzy-Based STATCOM Controller

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Mezigebu Getinet Yenealem ◽  
Livingstone M. H. Ngoo ◽  
Dereje Shiferaw ◽  
Peterson Hinga
Keyword(s):  
Distribution System ◽  
Power Loss ◽  
Power Flow ◽  
Fossil Fuels ◽  
Distribution Network ◽  
Voltage Profile ◽  
Static Synchronous Compensator ◽  
Voltage Unbalance ◽  
Load Demand ◽  
Power Loss Reduction

The expansion of renewable energy is continuing powerfully. Electrical system ought to transmit power with diminished loss, improved power quality, and reliability while pleasing the need of customer’s load demand. Nevertheless, owing to the exhaustion of fossil fuels and their environmental impact, the availability of quality, stable, and reliable power in developing countries is worrying. Integrating a solar-wind based microgrid to the distribution network is the more feasible and best alternative solution to gratify the customer intensifying power demand while seeing the strict environmental regulations of generating power. However, the microgrid system connected in a distribution network has diverse problems and challenges. The problems comprise the development of voltage sag and swell, voltage unbalance, and power losses because of the intermittent nature of PV and wind resources. The objective of this study is to integrate microgrid system with STATCOM (static synchronous compensator) controller to ensure the higher power flow with enhanced voltage profile and reduced power loss. MATLAB/PSAT is used to model microgrid and STATCOM controller connected to the grid. Proportional integral (PI) and fuzzy logic controllers (FLC) are also applied to control the STATCOM. The effectiveness of STATCOM with microgrid integration is tested by connecting to the main distribution system using standard IEEE 30-bus system. Finally, it was observed that STATCOM raises the capacity of the distribution line and contributes to voltage profile improvements and power loss reduction.

The Influence and Countermeasures Research of Large-Scale Distributed Photovoltaic Access to the Distribution Network

2014 ◽  
Vol 953-954 ◽  
pp. 61-65
Author(s):  
Jing Chao Zhang ◽  
Zheng Gang Wang ◽  
Feng Zhen Zhou ◽  
Ning Xi Song ◽  
Qian Wang
Keyword(s):  
Power Generation ◽  
Renewable Energy ◽  
Power Flow ◽  
Large Scale ◽  
Industrial Revolution ◽  
Simulation Analysis ◽  
Negative Impact ◽  
Rapid Development ◽  
Distribution Network ◽  
Photovoltaic Power

In recent years, with the gradual depletion of traditional energy, as renewable energy representatives, new energy has developed rapidly. We know that distributed photovoltaic power generation with clean, pollution-free, easy installation, and therefore has been rapid development. However, the large number of distributed photovoltaic power generation connected to the distribution network would have a negative impact on the grid with a safe and reliable operation because of its randomness and volatility intrinsic properties. In this paper, in terms of power flow, voltage distribution, load characteristics, power quality, system protection and reliability departure, through MATLAB simulation analysis, the distribution network transformation strategies of primary and secondary devices has been proposed. It laid an important foundation for renewable energy development and the Third Industrial Revolution.

Microgrid Protection Based on Specific Current Injection

2013 ◽  
Vol 805-806 ◽  
pp. 1082-1086
Author(s):  
Jun Li ◽  
Zhi Fei Chen ◽  
Jun Xia Qian ◽  
Hui Gang Zhang
Keyword(s):  
Power Flow ◽  
Short Circuit ◽  
Distribution Network ◽  
Short Circuit Current ◽  
Current Injection ◽  
Harmonic Current ◽  
Matlab Simulink ◽  
Injection Method ◽  
Protection Scheme ◽  
Fault Type

Considering that microgrid (MG) can be controlled flexibly, its short circuit-current is limited and power flow is bidirectional. The paper presents a new relay protection scheme of microgrid based specific harmonic injection method. The injective harmonic flows all over microgrid and the amplitude of specific harmonic current will enhance in fault occasion. So the above characteristic can solve the problem of fault position and the symmetric characteristic can complete the identification of fault type. The discussion about the compatibility of microgrid protection and conventional distribution network line protection. At last, the combined microgrid model is built in Matlab/Simulink environment. The simulation result demonstrated that the above method can complete the identification of fault position and type and it also can coordinate with the traditional line protection well.

scholarly journals Interconnection Impact Analysis of Solar Photovoltaic Systems with Distribution Networks

2021 ◽  
Author(s):  
◽  
Michael Emmanuel
Keyword(s):  
Power Flow ◽  
Impact Analysis ◽  
Distribution Network ◽  
Solar Pv ◽  
Electric Grid ◽  
Pv System ◽  
Pv Systems ◽  
Wide Range ◽  
Distribution Feeder ◽  
The Impact

<p>As the solar PV technology continues to evolve as the most common distributed generation (DG) coupled with increasing interconnection requests, accurate modelling of the potential operational impacts of this game-changer is pivotal in order to maintain the reliability of the electric grid. The overall goal of this research is to conduct an interconnection impact analysis of solar PV systems at increasing penetration levels subject to the feeder constraints within the distribution network. This is carried out with a time series power flow analysis method to capture the time-varying nature of solar PV and load with their interactions with the distribution network device operations. Also, this thesis analyses multiple PV systems scenarios and a wide range of possible impacts to enable distribution system planners and operators understand and characterize grid operations with the integration of PV systems.  An evaluation of the operational and reliability performance of a grid-connected PV system based on IEC standards and industry guides is performed to detect design failures and avoid unnecessary delays to PV penetration. The performance analysis metrics in this research allow cross-comparison between PV systems operating under different climatic conditions. This thesis shows the significant impact of temperature on the overall performance of the PV system. This research conducts an interconnection study for spatially distributed single-phase grid-tied PV systems with a five minute-resolution load and solar irradiance data on a typical distribution feeder. Also, this research compares the performance of generator models, PQ and P |V |, for connecting PV-DG with the distribution feeder with their respective computational costs for a converged power flow solution.  More so, a method capable of computing the incremental capacity additions, measuring risks and upgrade deferral provided by PV systems deployments is investigated in this research. This thesis proposes surrogate metrics, energy exceeding normal rating and unserved energy, for evaluating system reliability and capacity usage which can be a very useful visualization tool for utilities. Also, sensitivity analysis is performed for optimal location of the PV system on the distribution network. This is important because optimal integration of PV systems is often near-optimal for network capacity relief issues as well.  This thesis models the impact of centralized PV variability on the electric grid using the wavelet variability model (WVM) which considers the key factors that affect PV variability such as PV footprint, density and cloud movement over the entire PV plant. The upscaling advantage from a single module and point irradiance sensor to geographic smoothing over the entire PV footprint in WVM is used to simulate effects of a utility-interactive PV system on the distribution feeder.  Further, the PV interconnection scenarios presented in this thesis have been modelled with different time scales ranging from seconds to hours in order to accurately capture and represent various impacts. The analysis and advancements presented in this thesis will help utilities and other stakeholders to develop realistic projections of PV systems impacts on the grid. Also, this research will assist in understanding and full characterization of PV integration with the grid to avoid unnecessary delays.</p>

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