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

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.

Download Full-text

A Novel Extension Decision-Making Method for Selecting Solar Power Systems

International Journal of Photoenergy ◽

10.1155/2013/108981 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6

Author(s):

Meng-Hui Wang

Keyword(s):

Decision Making ◽

Solar System ◽

Power Systems ◽

Power System ◽

Solar Power ◽

Important Task ◽

Extension Theory ◽

Solar Systems ◽

Load Demand ◽

Generating Capacity

Due to the complex parameters of a solar power system, the designer not only must think about the load demand but also needs to consider the price, weight, and annual power generating capacity (APGC) and maximum power of the solar system. It is an important task to find the optimal solar power system with many parameters. Therefore, this paper presents a novel decision-making method based on the extension theory; we call it extension decision-making method (EDMM). Using the EDMM can make it quick to select the optimal solar power system. The paper proposed this method not only to provide a useful estimated tool for the solar system engineers but also to supply the important reference with the installation of solar systems to the consumer.

Download Full-text

Under Frequency Load Shedding Techniques for Future Smart Power Systems

Handbook of Research on Smart Power System Operation and Control - Advances in Computer and Electrical Engineering ◽

10.4018/978-1-5225-8030-0.ch007 ◽

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.

Download Full-text

An Underfrequency Load Shedding Scheme with Minimal Knowledge of System Parameters

International Journal of Emerging Electric Power Systems ◽

10.1515/ijeeps-2014-0108 ◽

2015 ◽

Vol 16 (1) ◽

pp. 33-46 ◽

Cited By ~ 2

Author(s):

Athbel Joe ◽

S. Krishna

Keyword(s):

Power Systems ◽

Power System ◽

New England ◽

Load Shedding ◽

Spinning Reserve ◽

Generator System ◽

Pass Filter ◽

Low Pass Filter ◽

System Parameters ◽

Frequency Measurements

Abstract Underfrequency load shedding (UFLS) is a common practice to protect a power system during large generation deficit. The adaptive UFLS schemes proposed in the literature have the drawbacks such as requirement of transmission of local frequency measurements to a central location and knowledge of system parameters, such as inertia constant H and load damping constant D. In this paper, a UFLS scheme that uses only the local frequency measurements is proposed. The proposed method does not require prior knowledge of H and D. The scheme is developed for power systems with and without spinning reserve. The proposed scheme requires frequency measurements free from the oscillations at the swing mode frequencies. Use of an elliptic low pass filter to remove these oscillations is proposed. The scheme is tested on a 2 generator system and the 10 generator New England system. Performance of the scheme with power system stabilizer is also studied.

Download Full-text

A Load Shedding Scheme for Long Term Voltage Stability Enhancement by Multi-Stage Model Predictive Control

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.383-390.4735 ◽

2011 ◽

Vol 383-390 ◽

pp. 4735-4741

Author(s):

Yu He ◽

Jing Zhang ◽

Zhi Wei Peng ◽

Zhao Yang Dong

Keyword(s):

Model Predictive Control ◽

Power System ◽

New England ◽

Predictive Control ◽

Voltage Stability ◽

Control Method ◽

Load Shedding ◽

Stage Model ◽

Multi Stage

Power system load shedding has been used as an emergency control method to prevent possible power system instability problems. In this paper, a new multi-stage model predictive control based load shedding scheme is proposed to enhance long term voltage stability of a power system. The main advantage of this new method is the capability of the scheme to handle multi-stage control actions, which may also be disturbances to a power system at a critical status toward instability. A new cost function is defined for the model predictive control scheme. The proposed scheme is tested on the New England 39-bus system to validate its efficiency and effectiveness in preventing system long term voltage stability problems.

Download Full-text

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

Applied Sciences ◽

10.3390/app9050990 ◽

2019 ◽

Vol 9 (5) ◽

pp. 990 ◽

Cited By ~ 27

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.

Download Full-text

Slow flow solutions and stability analysis of single machine to infinite bus power systems

International Journal of Emerging Electric Power Systems ◽

10.1515/ijeeps-2020-0176 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

M. G. Suresh Kumar ◽

C. A. Babu

Keyword(s):

Power Systems ◽

Power System ◽

Single Machine ◽

Multiple Scales ◽

Operating Conditions ◽

Phase Portraits ◽

Slow Flow ◽

Approximate Analytical Expression ◽

Flow Equations ◽

Load Angle

Abstract Nonlinearity is a major constraint in analysing and controlling power systems. The behaviour of the nonlinear systems will vary drastically with changing operating conditions. Hence a detailed study of the response of the power system with nonlinearities is necessary especially at frequencies closer to natural resonant frequencies of machines where the system may jump into the chaos. This paper attempt such a study of a single machine to infinite bus power system by modelling it as a Duffing equation with softening spring. Using the method of multiple scales, an approximate analytical expression which describes the variation of load angle is derived. The phase portraits generated from the slow flow equations, closer to the jump, display two stable equilibria (centers) and an unstable fixed point (saddle). From the analysis, it is observed that even for a combination of parameters for which the system exhibits jump resonance, the system will remain stable if the variation of load angle is within a bounded region.

Download Full-text

Effect of Hybrid Power Station Installation in the Operation of Insular Power Systems

Inventions ◽

10.3390/inventions4030038 ◽

2019 ◽

Vol 4 (3) ◽

pp. 38 ◽

Cited By ~ 3

Author(s):

Bouzounierakis ◽

Katsigiannis ◽

Fiorentzis ◽

Karapidakis

Keyword(s):

Energy Storage ◽

Power Systems ◽

Power System ◽

Large Scale ◽

Storage System ◽

Power Station ◽

Hybrid Power ◽

Load Demand ◽

Test Operation ◽

Hourly Data

Greece has a large number of islands that are isolated from the main interconnected Greek power system; however, a majority of them are to be interconnected in the mainland grid over the next decade. A large number of these islands present a significant amount of wind and solar potential. The nature of load demand and renewable production is stochastic; thus, the operation of such isolated power systems can be improved significantly by the installation of a large-scale energy storage system. The role of storage is to compensate for the long and short-term imbalances between power generation and load demand. Pumped hydro storage (PHS) systems represent one of the most mature technologies for large-scale energy storage. However, their advantages have not been proven in practice for cases of medium and small-sized isolated insular systems. Regarding Greece, which contains a large number of isolated insular systems, a PHS system in the island of Ikaria started its test operation in 2019, whereas in Europe only one PHS system operates in El Hierro (Canary Islands). This paper studies the effect of installing a wind-PHS hybrid power station in the operation of the insular power system of Samos, Greece, according to the latest regulatory framework. The implemented analysis uses real hourly data for a whole year, and examines the effects of such an installation considering investors’ and power system operators’ viewpoints. More specifically, the economic viability of this project under different billing scenarios is compared, and its impact on the insular power system operation for various PHS sizes is examined.

Download Full-text