scholarly journals Grid-connected Response Verification of AC Microgrid under Single Line-to-ground Short Circuit

2019 ◽  
pp. 1-10
Author(s):  
Maruf A. Aminu
Keyword(s):  
Power Systems ◽  
Reactive Power ◽  
Short Circuit ◽  
Synchronous Generator ◽  
Dynamic Responses ◽  
Single Line ◽  
Physical Systems ◽  
Short Circuits ◽  
Power System Performance ◽  
Grid Interconnection

In design of power systems, assumptions are made to model the physical systems. The assumptions may not sufficiently reflect the behavior of the system under normal and faulted conditions. Under short circuit conditions, system parameters vary significantly, particularly in microgrids with grid interconnection capabilities. This paper presents the result of validating the response of a microgrid which is capable of grid interconnection and islanding under voltage and reactive power control regimes. The microgrid is modeled to incorporate two wind turbines, each rated 5.5 kW, 400 V. The utility has synchronous generator rated 100 MW, 13.8 kV. Both the utility and microgrid are capable of exchanging active power and reactive power. Single line-to-ground short circuits are introduced and withdrawn at 30.00 s and 32.00 s, respectively. The dynamic responses of the testbed are captured pre-, during- and post-short circuit in grid-connected mode under both control regimes. The response of the testbed is verified to be consistent with established short circuit theory, verifying the validity of the system for short circuit detection and analysis. The testbed can therefore be used for short circuit and related studies, design optimization and power system performance prediction.

scholarly journals ANALYSIS OF OVERVOLTAGE POSSIBILITY ON THE EXCITATION WINDING OF A SYNCHRONOUS GENERATOR OF AUTONOMOUS POWER SUPPLY SYSTEM IN CASE OF EXTERNAL SYMMETRICAL SHORT CIRCUIT

2021 ◽  
pp. 112-115
Author(s):  
V.B. Beliy ◽  
Keyword(s):  
Power Systems ◽  
Power Supply ◽  
Short Circuit ◽  
Electric Energy ◽  
Synchronous Generator ◽  
Synchronous Generators ◽  
Excitation System ◽  
Three Phase ◽  
Short Circuits ◽  
Analytical Expressions

Reliable supply of consumers with electric energy largely depends on the reliability of power source function-ing. In the context of this paper it depends on synchronous generators operating in autonomous power supply sys-tems. In contrast to the power plant generators which are part of power systems and are protected from the loads by sufficiently large resistances, power supply systems withautonomous generators are characterized by rather low resistances. Abrupt changes in the supply load parameters, their own transient and emergency modes, for example, short circuits at the generator terminals, forcing excitation, etc. may lead to various failures in the synchronous gener-ator operation. This paper discusses the possibility of over-voltage in the valve excitation system of a synchronous generator with external three-phase short circuits. On the basis of analytical expressions describing the physical pro-cesses occurring in the excitation system of synchronous generators, the conditions for the occurrence of overvolt-ages are identified

scholarly journals Load Flow Analysis in Hybrid AC-DC Transmission Network

2021 ◽  
pp. 617-624
Author(s):  
Ajith M ◽  
Dr. R. Rajeswari
Keyword(s):  
Power Systems ◽  
Power System ◽  
Transmission Lines ◽  
Power Flow ◽  
Reactive Power ◽  
Short Circuit ◽  
Flow Analysis ◽  
Load Flow ◽  
System Stability ◽  
And Control

Power-flow studies are of great significance in planning and designing the future expansion of power systems as well as in determining the best operation of existing systems. Technologies such as renewables and power electronics are aiding in power conversion and control, thus making the power system massive, complex, and dynamic. HVDC is being preferred due to limitations in HVAC such as reactive power loss, stability, current carrying capacity, operation and control. The HVDC system is being used for bulk power transmission over long distances with minimum losses using overhead transmission lines or submarine cable crossings. Recent years have witnessed an unprecedented growth in the number of the HVDC projects. Due to the vast size and inaccessibility of transmission systems, real time testing can prove to be difficult. Thus analyzing power system stability through computer modeling and simulation proves to be a viable solution in this case. The motivation of this project is to construct and analyze the load flow and short circuit behavior in an IEEE 14 bus power system with DC link using MATLAB software. This involves determining the parameters for converter transformer, rectifier, inverter and DC cable for modelling the DC link. The line chosen for incorporation of DC link is a weak bus. This project gives the results of load flow and along with comparison of reactive power flow, system losses, voltage in an AC and an AC-DC system.

On the Problem of Selecting and Replacing Current Transformers for Relay Protection Devices

2020 ◽  
Vol 63 (6) ◽  
pp. 72-82
Author(s):  
Stanislav Kuzhekov ◽  
◽  
Andrey Degtyarev ◽  
Nikolay Doni ◽  
Aleksey Shurupov ◽  
...  
Keyword(s):  
Power Systems ◽  
High Speed ◽  
Short Circuit ◽  
Relay Protection ◽  
Electric Power Systems ◽  
Current Transformers ◽  
Magnetic Cores ◽  
Protection Devices ◽  
Short Circuits ◽  
The Stability

In connection with cases of incorrect operation of high-speed relay protection devices (RPD) in case of short circuits outside their range, the issue of replacing current transformers (CT) of class P with more ad-vanced current converters is relevant. The article shows that the decision to replace existing class P CTs with CTs with a non-magnetic gap should be made taking into account the probability of saturation of the magnetic cores of the latter in a transient short-circuit mode, as well as an increase in their dimensions compared to class P CTs. The issue of using optoelectronic current converters should be resolved after the latter are put into mass production, taking into account the difficulty of integrating the latter with the RPDs implemented using an Electromechanical base. In many cases, the correct functioning of high-speed RPDs without replacing existing CTs of class P can provide the following measures: the use of algorithms that increase the stability of the oper-ation of high-speed RPDs when the CT is saturated; taking into account in the calculations of the settings the rectangular characteristic of the CT magnetization in transient modes and the permissible deceleration of pro-tections under the condition of the dynamic stability of electric power systems; refusal to use CT connection groups (physical sum of currents, delta and star).

scholarly journals The Short-Circuit Protections in Hybrid Systems with Low-Power Synchronous Generators

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 160
Author(s):  
Bartosz Rozegnał ◽  
Paweł Albrechtowicz ◽  
Dominik Mamcarz ◽  
Natalia Radwan-Pragłowska ◽  
Artur Cebula
Keyword(s):  
Single Phase ◽  
Low Voltage ◽  
Short Circuit ◽  
Circuit Breaker ◽  
Synchronous Generator ◽  
Synchronous Generators ◽  
Electrical Systems ◽  
Protection Devices ◽  
Short Circuits ◽  
Damage Type

Single-phase short-circuits are most often faults in electrical systems. The analysis of this damage type is taken for backup power supply systems, from small power synchronous generators. For these hybrid installations, there is a need for standard protection devices, such as fuses or miniature circuit breaker (MCB) analysis. Experimental research mentioned that a typical protective apparatus in low-voltage installations, working correctly during supplying from the grid, does not guarantee fast off-switching, while short-circuits occur during supplication from the backup generator set. The analysis of single-phase short-circuits is executed both for current waveform character (including sub-transient and transient states) and the carried energy, to show the problems with the fuses and MCB usage, to protect circuits in installations fed in a hybrid way (from the grid and synchronous generator set).

A Comprehensive Review of Power Quality Issues and Measurement for Grid-Integrated Wind Turbines

2019 ◽  
Vol 12 (3) ◽  
pp. 210-222
Author(s):  
Ahmed F. Zobaa ◽  
Ibrahim Ahmed ◽  
Shady H.E. Abdel Aleem
Keyword(s):  
Power Systems ◽  
Wind Energy ◽  
Power Quality ◽  
Reactive Power ◽  
Short Circuit ◽  
Energy Systems ◽  
Short Circuit Current ◽  
Quality Performance ◽  
Quality Aspects ◽  
Wind Energy Systems

Background: Renewable energy generation using wind energy has emerged worldwide and has opened up significant new markets in electrical power generation. However, different factors that affect power quality performance of Wind Turbine (WT) applications such as wind speed fluctuation and use of power electronic based devices have been presented due to the rapid increase of WT installations. Methods: Accordingly, it is worth to measure, assess and evaluate the quality of the generated power of these WTs in order to ensure their compliance with the grid-integration conditions. In this work, first, a general classification of WTs and their operating principle is reviewed. Because variable speed WTs are frequently used in today’s power systems, much attention was paid to this type of turbines. Second, the various power quality aspects caused due to the integration of the wind energy systems into the grid were presented and discussed. Flickers, harmonic distortion, response to voltage dip, active power, and reactive power requirements, fault-ride through and short-circuit current contribution were the addressed power quality problems. Results: Further, the study pointed out the need for a unified evaluation process to assess the power quality performance of the grid-connected wind systems. Conclusion: Also, it was concluded that success in integrating more wind energy systems hinges on accurate power quality performance assessment.

scholarly journals Optimization to Limit the Effects of Underloaded Generator Sets in Stand-Alone Hybrid Ship Grids

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 708 ◽  
Author(s):  
Sergey German-Galkin ◽  
Dariusz Tarnapowicz ◽  
Zbigniew Matuszak ◽  
Marek Jaskiewicz
Keyword(s):  
Power Systems ◽  
Power Distribution ◽  
Reactive Power ◽  
Negative Impact ◽  
Combustion Engine ◽  
Synchronous Generator ◽  
Parallel Operation ◽  
Variable Speed ◽  
Diesel Generator ◽  
Power Load

For the safety of the supply, diesel generator (DG) sets are used in various stand-alone power systems using variable-speed generators. The stand-alone hybrid grid system presented in this article, with a wind generator and a diesel generator, but also the system of a ship’s network, serves as an example. To ensure the safety of the ship’s exploitation, the parallel operation of two stand-alone power supplies is required. In parallel operation with the required symmetrical active power load (regardless of the load size), the internal combustion engine of the DG set is often underloaded. This leads to deterioration of its technical properties and, consequently, to a negative impact on the environment. This article presents an analysis of the stand-alone hybrid power system of a ship’s grid consisting of a DG with a speed and voltage regulator and a shaft generator of variable speed—a permanent magnet synchronous generator (PMSG). The possibility of controlling the active and reactive power distribution between the DG and shaft generator (SG) was also studied. Control over the mechatronic SG–DG system limits the harmful influence of the DG on the environment and, most of all, improves the technical qualities of the engine of the DG system, which is often underloaded. Analytic studies of the system were performed, and simulation results of the mechatronic model are presented.

scholarly journals ANN based SVC FACTS Controller to Enhance Voltage Stability of Multi-Machine Power System

2019 ◽  
Vol 8 (10) ◽  
pp. 381-387
Keyword(s):  
Power Systems ◽  
Power Supply ◽  
Voltage Stability ◽  
Reactive Power ◽  
Short Circuit ◽  
Supply And Demand ◽  
Optimal Location ◽  
Voltage Sensitivity ◽  
Index Value ◽  
Weak Bus

Voltage stability is the most vital phenomena in power systems which may be disturbed by the mismatch between the reactive power supply and demand. The occurrence of internal faults in the equipment and short circuit faults also there may be voltage collapse at the buses. Voltage stability can be improved using Static VAR Compensator (SVC) which is a shunt device. It can generate or absorb reactive power in a controlled manner such that it can enhance voltage stability of the system. LIndex method is used to determine voltage sensitivity at each bus and the bus having highest L- index value can be considered as a weak bus which is the optimal location of FACTS controller. The investigation is made to observe how susceptance in susceptance model and firing angle in firing angle model of the SVC is predicted to enhance the voltage at each bus by the artificial neural network under chaotic load. Standard IEEE 5 bus and 30 bus systems are considered as test systems and simulations are performed in MATLAB software.

scholarly journals Detecting the single line to ground short circuit fault in the submarine’s power system using the artificial neural network

2013 ◽  
Vol 10 (3) ◽  
pp. 445-457
Author(s):  
Ali Behniafar ◽  
Ahmad Darabi ◽  
Mahdi Banejad ◽  
Mohammadreza Baghayipour
Keyword(s):  
Neural Network ◽  
Power Systems ◽  
Power System ◽  
Short Circuit ◽  
Single Line ◽  
Special Importance ◽  
Double Line ◽  
Ground Fault ◽  
Different Types ◽  
Short Circuit Fault

The electric marine instruments are newly inserted in the trade and industry, for which the existence of an equipped and reliable power system is necessitated. One of the features of such a power system is that it cannot have an earth system causing the protection relays not to be able to detect the single line to ground short circuit fault. While on the other hand, the occurrence of another similar fault at the same time can lead to the double line fault and thereby the tripping of relays and shortening of vital loads. This in turn endangers the personals' security and causes the loss of military plans. From the above considerations, it is inferred that detecting the single line to ground fault in the marine instruments is of a special importance. In this way, this paper intends to detect the single line to ground fault in the power systems of the marine instruments using the wavelet transform and Multi-Layer Perceptron (MLP) neural network. In the numerical analysis, several different types of short circuit faults are simulated on several marine power systems and the proposed approach is applied to detect the single line to ground fault. The results are of a high quality and preciseness and perfectly demonstrate the effectiveness of the proposed approach.

Symmetrical Short Circuit Parameter Differences of Double Fed Induction Generator and Synchronous Generator Based Wind Turbine

2017 ◽  
Vol 6 (2) ◽  
pp. 268 ◽  
Author(s):  
Muhammad Shahzad Nazir ◽  
Qinghua Wu ◽  
Mengshi Li ◽  
Luliang Zhang
Keyword(s):  
Power Systems ◽  
Wind Power ◽  
Fault Tolerant ◽  
Short Circuit ◽  
Power Conversion ◽  
Synchronous Generator ◽  
Circuit Parameter ◽  
Transient Time ◽  
Induction Generators ◽  
Wind Power Systems

<p>Considering the importance of perturbations during short circuit (SC) in power conversion devices, this study designed to find out the efficacy of symmetrical short circuit (SSC) of the synchronous generator (SG) and doubly fed induction generators (DFIG). Both wind power systems were separately built (Park’s model) and simulated. Simulation results showed that the DFIG is more efficient, fault tolerant, and proficient systems as compared to the SG based on the transient time, steady state, maximum current, and voltage dip values. This study can extend to design protection schemes, more accurate, stable and optimal proficient wind power conversion devices.</p>

scholarly journals Islanded Mode Response Verification of AC Microgrid under Symmetrical and Non-symmetrical Short Circuits

2019 ◽  
Vol 115 ◽  
pp. 01002
Author(s):  
Maruf A. Aminu
Keyword(s):  
Wind Turbines ◽  
Reactive Power ◽  
Control Strategies ◽  
Short Circuit ◽  
Islanded Mode ◽  
Short Circuits ◽  
Detection And Diagnosis ◽  
And Performance ◽  
Mode Response ◽  
Optimization And Performance

The assumptions and parameters required in modeling a microgrid depend on the platform, among other variables. It is therefore pertinent to verify the response of a modeled testbed to establish its validity. This work reports on verification of the response of a wind turbines-based microgrid to symmetrical and non-symmetrical short circuits. The testbed consists of 2 units of 5.5 kW 400 V wind turbines capable of connecting to the utility. Short circuits are introduced at 6.00 second and withdrawn at 8.00 second, measuring the dynamic response of the testbed while the microgrid is in islanded mode alternately under voltage and reactive power control strategies. The response is shown to be consistent, symptomatic of the type of short circuit and therefore suitable for short circuit detection and diagnosis, verifying validity of the microgrid testbed. The testbed can therefore be used for short circuit related studies, design optimization and performance prediction.

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