Analysis of Under-frequency Load Shedding (UFLS) Relay Setting during Disturbances

2020 ◽  
Vol 3 (2) ◽  
pp. 132-135
Author(s):  
Irrine Budi Sulistiawati ◽  
Angga Budi Prastyo ◽  
Abraham Lomi ◽  
Ardyono Priyadi
Keyword(s):  
System Performance ◽  
Load Shedding ◽  
System Stability ◽  
Load Demand ◽  
On Line ◽  
System Frequency

Load changes on the system will affect the system stability itself.  Load demand that exceeds the generated power will cause the system frequency to decline. Therefore, a load shedding procedure is required to improve the frequency. This research focuses on how to design a load shedding scheme that is activated by the operation of under frequency relay. There are two scenarios to analyze the system performance with a simulation, which are losing power on line about 128 MVA and generator loss power about 192 MVA. Those scenarios result in a decrease in the system frequency to 47.48 Hz and 47.90, respectively. After the load shedding scenario is performed, the frequency became an increase in the range of 51.54 Hz and 49 Hz within a few seconds.

Under Frequency Load Shedding Techniques for Future Smart Power Systems

2019 ◽  
pp. 188-202
Author(s):  
H. H. Alhelou
Keyword(s):  
Power Systems ◽  
Power System ◽  
Active Power ◽  
Load Shedding ◽  
System Stability ◽  
Special Focus ◽  
Power Demand ◽  
Synchronous Generators ◽  
Smart Power ◽  
System Frequency

It is critical for today's power system to remain in a state of equilibrium under normal conditions and severe disturbances. Power imbalance between the load and the generation can severely affect system stability. Therefore, it is necessary that these imbalance conditions be addressed in the minimum time possible. It is well known that power system frequency is directly proportional to the speed of rotation of synchronous machines and is also a function of the active power demand. As a consequence, when active power demand is greater than the generation, synchronous generators tends to slow down and the frequency decreases to even below threshold if not quickly addressed. One of the most common methods of restoring frequency is the use of under frequency load shedding (UFLS) techniques. In this chapter, load shedding techniques are presented in general but with special focus on UFLS.

scholarly journals An approach for a multi-stage under-frequency based load shedding scheme for a power system network

2020 ◽  
Vol 10 (6) ◽  
pp. 6071
Author(s):  
Mkhululi Elvis Siyanda Mnguni ◽  
Yohan Darcy Mfoumboulou
Keyword(s):  
Decision Making ◽  
Power Systems ◽  
Power System ◽  
New England ◽  
Operating Conditions ◽  
Load Shedding ◽  
Power Network ◽  
Load Demand ◽  
Multi Stage ◽  
System Frequency

The integration of load shedding schemes with mainstream protection in power system networks is vital. The traditional power system network incorporates different protection schemes to protect its components. Once the power network reaches its maximum limits, and the load demand continue to increase the whole system will experience power system instability. The system frequency usually drops due to the loss of substantial generation creating imbalance. The best method to recover the system from instability is by introducing an under-frequency load shedding (UFLS) scheme in parallel with the protection schemes. This paper proposed a new UFLS scheme used in power systems and industry to maintain stability. Three case studies were implemented in this paper. Multi-stage decision-making algorithms load shedding in the environment of the DIgSILENT power factory platform is developed. The proposed algorithm speeds-up the operation of the UFLS scheme. The load shedding algorithm of the proposed scheme is implemented as a systematic process to achieve stability of the power network which is exposed to different operating conditions. The flexibility of the proposed scheme is validated with the modified IEEE 39-bus New England model. The application of the proposed novel UFLS schemes will contribute further to the development of new types of engineers.

scholarly journals Principal Component Analysis (PCA)-Supported Underfrequency Load Shedding Algorithm

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5896
Author(s):  
Tadej Skrjanc ◽  
Rafael Mihalic ◽  
Urban Rudez
Keyword(s):  
Principal Component ◽  
Operating Conditions ◽  
Load Shedding ◽  
Fine Tuning ◽  
System Stability ◽  
Degree Of Certainty ◽  
Conceptual Shift ◽  
Available Information ◽  
High Degree ◽  
System Frequency

This research represents a conceptual shift in the process of introducing flexibility into power system frequency stability-related protection. The existing underfrequency load shedding (UFLS) solution, although robust and fast, has often proved to be incapable of adjusting to different operating conditions. It triggers upon detection of frequency threshold violations, and functions by interrupting the electricity supply to a certain number of consumers, both of which values are decided upon beforehand. Consequently, it often does not comply with its main purpose, i.e., bringing frequency decay to a halt. Instead, the power imbalance is often reversed, resulting in equally undesirable frequency overshoots. Researchers have sought a solution to this shortcoming either by increasing the amount of available information (by means of wide-area communication) or through complex changes to all involved protection relays. In this research, we retain the existing concept of UFLS that performs so well for fast-occurring frequency events. The flexible rebalancing of power is achieved by a small and specialized group of intelligent electronic devices (IEDs) with machine learning functionalities. These IEDs interrupt consumers only when the need to do so is detected with a high degree of certainty. Their small number assures the fine-tuning of power rebalancing and, at the same time, poses no serious threat to system stability in cases of malfunction.

scholarly journals WAMS-Based Online Disturbance Estimation in Interconnected Power Systems Using Disturbance Observer

2019 ◽  
Vol 9 (5) ◽  
pp. 990 ◽  
Author(s):  
Hassan Haes Alhelou ◽  
Mohamad Hamedani Golshan ◽  
Takawira Njenda ◽  
Pierluigi Siano
Keyword(s):  
Power Systems ◽  
Power System ◽  
Disturbance Observer ◽  
Load Shedding ◽  
System Stability ◽  
Main Stage ◽  
Estimation Errors ◽  
Disturbance Estimation ◽  
System Frequency ◽  
Swing Equation

In the event of a generator loss or disturbance, the power system frequency declines quickly and overall system stability is at risk. During these scenarios, under frequency load shedding is triggered to restore the power system frequency. The main stage of modern adaptive under frequency load shedding techniques is disturbance estimation. However, the swing equation is widely used in disturbance estimation but has some critical estimation errors. In this paper, instead of using the swing equation we proposed the use of a disturbance observer to estimate the curtailed power. By making use of wide area measurements, a system frequency response model, which is a representative of the whole power system, can be realized in real time. Using different power system states of the developed model, a disturbance observer can be designed as well. The main advantage of the disturbance observer is that it can accurately estimate the disturbance magnitude and its location in a very short time. Further investigations show that by using the disturbance observer disturbances, which occur at the same time or at different times in different areas regardless of the magnitude or size, accurate estimations can be made. To ascertain the efficiency of the proposed scheme, simulations are done for a four-area power system using Matlab/Simulink.

scholarly journals Review of under Frequency Load Shedding Program of Kosovo Power System based on ENTSO-E Requirements

2018 ◽  
Vol 8 (2) ◽  
pp. 741
Author(s):  
Gazmend Kabashi ◽  
Skender Kabashi
Keyword(s):  
Power System ◽  
System Performance ◽  
Large Scale ◽  
Load Shedding ◽  
Southeast Europe ◽  
Dynamic Simulations ◽  
Interconnected Power System ◽  
Frequency Behavior ◽  
System Frequency

Under-frequency load shedding (UFLS) is designed to protect the power system when the frequency drops below given thresholds by switching off certain amounts of the load aiming thus to balance generation and load. This paper presents a review of the existing UFLS (Under Frequency Load Shedding) program in compliance with recently revised Police-5 of Operational Handbook of ENTSO-e. The proposed review of the current UFLS program for Kosovo Power System has considered the main standards requirements and guidelines for UFLS set by ENTSO-E. This work examine system performance by conducting dynamic simulations of UFLS schemes subject to different imbalances between load and generation, and includes three power system island mode scenarios with different equivalent inertia of the system, respectively different size of the systems. With aim to define the best program of UFLS, which fits to the Kosovo Power System frequency behavior, two different UFLS programs are analyzed and results are compared. The proposed program is tested using a large scale PSS/E model which represents interconnected power system area of Southeast Europe.

Frequency and inertia response effects, capabilities, and possibilities in renewable energy sources

2021 ◽  
Vol 14 ◽  
Author(s):  
Jishu Mary Gomez ◽  
Prabhakar Karthikeyan Shanmugam
Keyword(s):  
Renewable Energy ◽  
Power System ◽  
Frequency Control ◽  
Renewable Energy Sources ◽  
Energy Systems ◽  
Load Shedding ◽  
System Stability ◽  
Frequency Regulation ◽  
Control Schemes ◽  
Inertia Response

Background & Objectives: The global power system is in a state of continuous evolution, incorporating more and more renewable energy systems. The converter-based systems are void of inherent inertia control behavior and are unable to curb minor frequency deviations. The traditional power system, on the other hand, is made up majorly of synchronous generators that have their inertia and governor response for frequency control. For improved inertial and primary frequency response, the existing frequency control methods need to be modified and an additional power reserve is to be maintained mandatorily for this purpose. Energy self-sufficient renewable distributed generator systems can be made possible through optimum active power control techniques. Also, when major global blackouts were analyzed for causes, solutions, and precautions, load shedding techniques were found to be a useful tool to prevent frequency collapse due to power imbalances. The pre-existing load shedding techniques were designed for traditional power systems and were tuned to eliminate low inertia generators as the first step to system stability restoration. To incorporate emerging energy possibilities, the changes in the mixed power system must be addressed and new frequency control capabilities of these systems must be researched. Discussion: In this paper, the power reserve control schemes that enable frequency regulation in the widely incorporated solar photovoltaic and wind turbine generating systems are discussed. Techniques for Under Frequency Load Shedding (UFLS) that can be effectively implemented in renewable energy enabled micro-grid environment for frequency regulation are also briefly discussed. The paper intends to study frequency control schemes and technologies that promote the development of self- sustaining micro-grids. Conclusion: The area of renewable energy research is fast emerging with immense scope for future developments. The comprehensive literature study confirms the possibilities of frequency and inertia response enhancement through optimum energy conservation and control of distributed energy systems.

scholarly journals Hybrid Fuzzy Load Frequency Controller for a Two Area Interconnected Power System

2012 ◽  
pp. 278-282
Author(s):  
U. Prasad ◽  
P.K. Mohanty ◽  
P.K. Chattopadhyaya ◽  
C.K. Panigrahi
Keyword(s):  
Power System ◽  
Fuzzy Logic Controller ◽  
Fuzzy Controller ◽  
Control Strategies ◽  
Automatic Generation ◽  
Dynamic Responses ◽  
System Stability ◽  
Interconnected Power System ◽  
Stability Issues ◽  
System Frequency

This work addresses the special requirements of Automatic Generation Control in Modern interconnected Power system. In order to track the system frequency and handling the power system stability issues many control strategies has been suggested by the researchers .A new Hybrid fuzzy approach is introduced here .Fuzzy Logic controller with Mamdani interface having five member ship functions is tested with the Thermal Thermal and hydro thermal system Further hybrid Fuzzy controller is also tested with the same system and results are compared for the both The system Which is having Hybrid Fuzzy concept and thereby the response of frequency and tie line power can be improved substantially following a load change in any area. Further dynamic responses for small perturbation have been observed, considering HFLC and integral controller and the results of both have been compared.

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