scholarly journals Voltage Stability of Power Systems with Renewable-Energy Inverter-Based Generators: A Review

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 115
Author(s):  
Nasser Hosseinzadeh ◽  
Asma Aziz ◽  
Apel Mahmud ◽  
Ameen Gargoom ◽  
Mahbub Rabbani
Keyword(s):  
Renewable Energy ◽  
Power Systems ◽  
Voltage Stability ◽  
Reactive Power ◽  
Power Grid ◽  
Renewable Energy Sources ◽  
Electrical Power ◽  
System Stability ◽  
Special Issue ◽  
Synchronous Generators

The main purpose of developing microgrids (MGs) is to facilitate the integration of renewable energy sources (RESs) into the power grid. RESs are normally connected to the grid via power electronic inverters. As various types of RESs are increasingly being connected to the electrical power grid, power systems of the near future will have more inverter-based generators (IBGs) instead of synchronous machines. Since IBGs have significant differences in their characteristics compared to synchronous generators (SGs), particularly concerning their inertia and capability to provide reactive power, their impacts on the system dynamics are different compared to SGs. In particular, system stability analysis will require new approaches. As such, research is currently being conducted on the stability of power systems with the inclusion of IBGs. This review article is intended to be a preface to the Special Issue on Voltage Stability of Microgrids in Power Systems. It presents a comprehensive review of the literature on voltage stability of power systems with a relatively high percentage of IBGs in the generation mix of the system. As the research is developing rapidly in this field, it is understood that by the time that this article is published, and further in the future, there will be many more new developments in this area. Certainly, other articles in this special issue will highlight some other important aspects of the voltage stability of microgrids.

scholarly journals Development of mechanical coupling and exciter system in synchronous generators

2021 ◽  
Vol 6 (8 (114)) ◽  
Author(s):  
Raad Lafta Damij
Keyword(s):  
Renewable Energy ◽  
High Speed ◽  
Fossil Fuels ◽  
Reactive Power ◽  
Renewable Energy Sources ◽  
Circuit Breaker ◽  
System Stability ◽  
Synchronous Generators ◽  
Excitation System ◽  
Mechanical Coupling

Power is generated in a variety of ways, including renewable energy, nuclear power, and burning of fossil fuels. The majority of our power is currently generated by burning fossil fuels, mostly natural gas and coal, to spin turbines attached to an electromagnetic generator. The main advantage of AC generation is that the voltage levels can be altered up and down with transformers, allowing electricity to be sent across long distances to the loads that demand it. The excitation system demand for large synchronous generators with a few hundred-megawatt ratings becomes very enormous. The challenge of transmitting such a big amount of power through high-speed sliding contacts becomes daunting. Mechanical coupling with exciter for synchronous generators is essential to mitigate such problems as the corrected output is linked directly to the field winding. This paper aims to develop a simulation of a 3-phase diesel engine-based 2 MVA/400 V synchronous generator with mechanical coupling and an exciter system. The developed simulation of the synchronous machine is set to deliver 25 % of its rating value (500 kW) till the time of 3 sec. Then, additional power of 1 MW is switched at t=3 sec via a 3-phase circuit breaker. The dynamic response of field current and field voltage of the simulation shows reasonable step performance as the steady-state time is less than 3 sec. The control of the excitation system allows the generator to maintain voltage, control reactive power flow, and assist in maintaining power system stability. The simulation was accurate when measuring the voltage and current under these changes. This analysis can help to investigate further integration with renewable energy sources.

scholarly journals Voltage collapse point evaluation considering the load dependence in a power system stability problem

2020 ◽  
Vol 10 (1) ◽  
pp. 61 ◽  
Author(s):  
Zaid Garcia Sanchez ◽  
Jose Antonio González ◽  
Gustavo Crespo ◽  
Hernan Hernandez Herrera ◽  
Jorge Iván Silva
Keyword(s):  
Power Systems ◽  
Stability Problem ◽  
Voltage Stability ◽  
Electrical Power ◽  
Maximum Load ◽  
Point Load ◽  
System Stability ◽  
Voltage Collapse ◽  
Load Dependence ◽  
The Stability

<span lang="EN-US">Voltage Stability has emerged in recent decades as one of the most common phenomena, occurrence in Electrical Power Systems. Prior researches focused on the development of algorithm indices to solve the stability problem and in the determination of factors with most influence in voltage collapse to solve the stability problem. This paper evaluates the influence that the load dependence has with the voltage on the phenomenon of the voltage stability and especially on the characteristics the collapse point or instability point. Load modeling used is detailed and comparisons of the results obtained are made with those described in the bibliography and those obtained with commercial software. The results of the load margin are also compared when a constant load or a voltage-dependent load is considered as well as the values obtained at the maximum load point and the point of voltage instability.</span>

Microgrids Emergency Control and Protection

2013 ◽  
Vol 2 (1) ◽  
pp. 78-100 ◽  
Author(s):  
Hassan Bevrani ◽  
Mehrdad Gholami ◽  
Neda Hajimohammadi
Keyword(s):  
Power Systems ◽  
Large Scale ◽  
Reactive Power ◽  
Renewable Energy Sources ◽  
Voltage Regulation ◽  
System Stability ◽  
Stable Operation ◽  
Energy Storage Devices ◽  
Control Plan ◽  
Emergency Control

Economical harvesting of electrical energy on a large scale considering the environmental issues is a challenge. As a solution, Microgrids (MGs) promise to facilitate the widely penetration of renewable energy sources (RESs) and energy storage devices into the power systems, reduce system losses and greenhouse gas emissions, and increase the reliability of the electricity supply to the customers. Although the concept of MG is already established, the control strategies and energy management systems for MGs which cover power interchange, system stability, frequency and voltage regulation, active and reactive power control, islanding detection, grid synchronization, following contingencies and emergency conditions are still under development. Like a conventional power system, a Micro-grid (MG) needs emergency control and protection schemes to have secure and stable operation. Since MG can operate in both grid-connected and islanded mode, in addition to the control loops and protection schemes, extra issues must be considered. Transition between two operation modes requires an extra control plan to eliminate and stabilize transients due to mode changing. This paper presents an overview of the key issues and new challenges on emergency control and protection plans in the MG systems. The most important emergency control and protection schemes such as load shedding methods that have been presented over the past years are summarized.

scholarly journals Improvement of bus voltage profiles of Nigerian power network in the presence of Static Synchronous Compensator (STATCOM) and Doubly Fed Induction Generator (DFIG)

2020 ◽  
Vol 39 (1) ◽  
pp. 228-237
Author(s):  
I.B. Anichebe ◽  
A.O. Ekwue
Keyword(s):  
Renewable Energy ◽  
Stability Analysis ◽  
Power System ◽  
Power Flow ◽  
Voltage Stability ◽  
Reactive Power ◽  
Renewable Energy Sources ◽  
Load Flow ◽  
Energy Sources ◽  
Power Network

Frequent blackouts and unstable supply of electricity show that the  voltage instability problem has been one of the major challenges facing the power system network in Nigeria. This study investigates the voltage stability analysis of the Nigerian power network in the presence of renewable energy sources; FACTS device is used as a voltage controller. A 330kV, 28-bus power system network was studied using the PSS/E software-based Newton-Raphson load-flow technique. The results show that 10 out of the 28 buses had voltages lying below the statutory limit of 0.95 ≤ 1.05 p.u. The application of STATCOM and DFIG devices on two of the weakest buses restored the voltages to acceptable statutory limits. The total active and reactive power losses were reduced to 18.76% and 18.82% respectively. Keywords: Voltage stability analysis; Integration of renewable energy sources; FACTS controllers, Reactive Power, Power Flow.

Voltage Stability Assessment Techniques for Modern Power Systems

2020 ◽  
pp. 128-176 ◽  
Author(s):  
Mahiraj Singh Rawat ◽  
Shelly Vadhera
Keyword(s):  
Power Systems ◽  
Electricity Market ◽  
Voltage Stability ◽  
Renewable Energy Sources ◽  
Primary Objective ◽  
System Stability ◽  
Stability Assessment ◽  
Utility Companies ◽  
Operating Limits ◽  
Assessment Techniques

In recent times, most of the power systems are made to operate close to their operating limits owing to various reasons like slow pace of transmission line expansion, environmental constraints, deregulated electricity market, etc. Therefore, the issue of maintaining the system stability has become the primary objective of the utility companies. The recent development and integration of renewable energy sources have further pushed the modern power systems to system security risks. The voltage instability had been the major cause of recent blackouts around the world. The timely assessment of voltage stability can prevent the blackouts in the power systems. This chapter explores the classical as well as newly developed static voltage stability assessment techniques proposed by various researchers in recent years. Also, the chapter cater to the needs of undergraduate as well as graduate students, professional engineers, and researchers who all are working in the domain of power system voltage stability.

Research on Voltage Stability in Grid-Connected Large Wind Farms

2011 ◽  
Vol 354-355 ◽  
pp. 989-992
Author(s):  
An Lin
Keyword(s):  
Power Systems ◽  
Voltage Stability ◽  
Wind Farm ◽  
Reactive Power ◽  
Low Voltage ◽  
Wind Farms ◽  
System Stability ◽  
Induction Generator ◽  
Induction Generators ◽  
Large Wind

Squirrel-cage induction generator (SCIG) has been widely utilized in large wind farms in China. However, the large wind farm composed of induction generators will cause obvious power system stability problems due to the dependency on reactive power. Doubly-fed induction generator (DFIG) has excellent dynamic characteristics of wind farm operations. With the increasing of wind power penetration in power systems, more and more wind farms use both SCIG and DFIG. This paper firstly analyzes the the dynamic characteristic of wind farm on power systems, especially in terms of the voltage stability. Then the interaction between the SCIGs and DFIGs is also investigated. A detailed simulation model of wind farms is presented by means of MATLAB. The simulation results demonstrate that the DFIG applications will improve the voltage stability of the wind farm largely and the low voltage ride through characteristics of SCIG to some extend.

scholarly journals Challenges in Integrating Renewable Sources into a Utility Grid

2020 ◽  
Vol 9 (3) ◽  
pp. 91-97
Keyword(s):  
Renewable Energy ◽  
Power Systems ◽  
Large Scale ◽  
Renewable Energy Sources ◽  
Electrical Power ◽  
Clean Energy ◽  
Energy Sources ◽  
Electrical Power System ◽  
Renewable Sources ◽  
Utility Grid

In India, Electrical Power System is adapted to handle both constant loads and variable loads, also power is generated in two types; one is due to fossil fuels, and another one is due to renewable energy sources. However, renewable energy sources are playing a vital role in the production of clean energy and also useful for the reduction in greenhouse emission. Nevertheless, when there is any additional change in the generation side concerning to input supply, which is due to the uncertainty of nature, can create new challenges for the system operators and utility centers. It is not an easy task for the utility centres and supply operators to integrate variable renewable energy sources with the utility grid. This paper explores an overview of some operational techniques and solutions, which are helpful for high penetration of renewable energy sources such as solar and wind energy. It also explores operation, control management and challenges due to renewable energy when they integrated with the utility grid. By interfacing of renewable energy sources with a utility grid with proper management and control can provide bi-directional communication between suppliers and consumers smartly. The aim of integrating large scale renewable sources from transmission and distribution network into an existing system is to reduce the power quality issues, demand response, forecasting, peak demand, and improve network security, fast scheduling and dispatch, aiming towards smart grid technology for electrical power systems.

scholarly journals Obtaining Probability Distribution Laws of Power System Steady-State Mode Parameters

2020 ◽  
Vol 20 (3) ◽  
pp. 41-51
Keyword(s):  
Renewable Energy ◽  
Probability Distribution ◽  
Power Systems ◽  
Power System ◽  
Renewable Energy Sources ◽  
Current Trend ◽  
System Stability ◽  
Energy Sources ◽  
Stable Operation ◽  
Distribution Laws

Stable operation of electrical power systems is one of the crucial issues in the power industry. Current vo­lumes of electricity consumption cause the need to constantly increase the generated capacity, repeatedly modifying and complicating the original circuit. In addition to this, given the current trend towards the use of digital power systems and renewable energy sources, more and more uncertainties difficult to predict by standard mathematical methods appear. Events in the power system are deterministic, i.e. random. Thus, it is difficult to fully assess the system stability, voltage levels, currents, or possible power losses. Finding the probability distribution laws can give us an understanding of all the possible states in which an object can exist. Obtaining them is complicated by the difficulty of accounting for all the correlations between the random arguments of the source data. These laws are necessary to determine the optimal operating modes, the possibility of solving the problem of determining the optimal renewable energy sources installation locations and the required amount of generated energy in a non-deterministic way. The purpose of this article is to test the developed SIBD method for obtaining the full probabilistic characteristics. This method, unlike the Monte Carlo methods, does not use a random sample of initial data, but completely covers the studied functional dependence. The problem was solved using the provisions of probability theory and mathematical statistics, numerical optimization methods in particular. The MATLAB Matpower application package was also used to solve technical computing problems.

scholarly journals Solar PV Placement and Sizing for Line Stability Enhancement and Optimal Operating Cost

2019 ◽  
Vol 9 (1) ◽  
pp. 3585-3593
Keyword(s):  
Power Systems ◽  
Power System ◽  
Voltage Stability ◽  
Reactive Power ◽  
Cost Minimization ◽  
Operating Cost ◽  
System Stability ◽  
Total Power ◽  
Solar Pv ◽  
Stability Enhancement

Nowadays, many countries have started to implement and installed solar photovoltaic (PV). The initial designs of existing power systems were not integrating with any renewable energy (RE) including PV. So, the small scale PV may not have any effect on these power systems. However, integrating large scale PV might raise several power quality issues including power system stability. Power system stability has become major attention where the main focus is on voltage stability.Voltage stability is related on electrical grid capacity to balance the Total Power of Demand (PD) and Total Power generated by Generator (Pgtt). Instability of the voltage can cause inability of the power system to meet the demand of reactive power. The lack of reactive power will cause instability in the power system.This paper present optimal placement and sizing of PV for stability enhancement and operating cost minimization. In this research, reactive power has gradually increased and Fast Voltage Stability Index (FVSI) is applied to analyze voltage stability. PV is applied to stabilize voltage stability of the power system. Economic Load Dispatch (ELD) is conducted to determine the optimal cost and loss. DEIANT is conducted to optimize the total cost and the total loss after solar PV implementation. Simulation result indicates the effectiveness of the proposed technique for stability enhancement and operating cost minimization.

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