An Optimal Load Shedding Methodology for Radial Power Distribution Systems to Improve Static Voltage Stability Margin using Gravity Search Algorithm

2014 ◽  
Vol 68 (3) ◽  
Author(s):  
Aziah Khamis ◽  
H. Shareef ◽  
A. Mohamed ◽  
Erdal Bizkevelci
Keyword(s):  
Power Distribution ◽  
Distribution System ◽  
Distribution Systems ◽  
Voltage Stability ◽  
Search Algorithm ◽  
Gravitational Search Algorithm ◽  
Stability Margin ◽  
Maximum Amount ◽  
Load Shedding ◽  
Voltage Stability Margin

Voltage stability is one of the major concerns in operational and planning of modern power system. Many strategies have been implemented to avoid voltage collapse, which the load shedding considered as the last option. However, optimization is needed to estimate the minimum amount to shed so as to prevent voltage instability. In this paper, an effective method is presented for estimating the optimal amount of load to be shed in a distribution system based on the gravitational search algorithm (GSA). The voltage stability margin (VSM) of the system has been considered in the objective function. The optimization problem is formulated to maximize the VSM of the system and at the same time satisfying the operation and security constraints. The optimum solution depends on the predefined constraints such as the number of load buses available to shed and the maximum amount of load permitted to shed. Simulation result conducted on the IEEE 33 bus radial distribution system shows that the system voltage stability can be improved by optimally shedding the loads at critical system buses. The results also indicate that the numbers of load buses available for load shedding does not have a significant impact on voltage stability margin, but it is highly dependent on the maximum amount of load permitted to shed. 

scholarly journals Probabilistic Hosting Capacity Enhancement in Non-Sinusoidal Power Distribution Systems Using a Hybrid PSOGSA Optimization Algorithm

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1018 ◽  
Author(s):  
Sherif Ismael ◽  
Shady Abdel Aleem ◽  
Almoataz Abdelaziz ◽  
Ahmed Zobaa
Keyword(s):  
Optimization Algorithm ◽  
Power Distribution ◽  
Distribution System ◽  
Distribution Systems ◽  
Search Algorithm ◽  
Gravitational Search Algorithm ◽  
Harmonic Distortion ◽  
Power Distribution System ◽  
Hybrid Particle Swarm Optimization ◽  
High Penetration

The high penetration of distributed generation (DG) units with their power-electronic interfaces may lead to various power quality problems, such as excessive harmonic distortions and increased non-sinusoidal power losses. In this paper, the probabilistic hosting capacity (PHC) due to the high penetration of photovoltaic units in a non-sinusoidal power distribution system is investigated. A C-type harmonic filter is proposed, to maximize the harmonic-constrained PHC. An optimization problem is formulated by using a Monte Carlo simulation, taking into account various uncertain parameters, such as the intermittent output power of the DGs, background voltage harmonics, load alteration, and the filter parameters’ variations. In addition, different operational constraints have been considered, such as the bus voltage, line thermal capacity, power factor, and individual and total harmonic distortion limits. A swarm-based, meta-heuristic optimization algorithm known as the hybrid particle swarm optimization and gravitational search algorithm (PSOGSA) has been examined for the optimal design of the proposed filter. Besides, other optimization algorithms were examined for validation of the solution. The PHC results obtained are compared with the conventional deterministic HC (DHC) results, and it is found that the PHC levels are higher than those obtained by conservative HC procedures, practical rules of thumb, and the DHC approaches.

scholarly journals Flexibility Enhancement in an Islanded Distribution Power System by Online Demand-Side Management

2019 ◽  
Vol 217 ◽  
pp. 01020 ◽  
Author(s):  
Margarita Chulyukova ◽  
Nikolai Voropai
Keyword(s):  
Power System ◽  
Power Distribution ◽  
Distribution System ◽  
Distribution Systems ◽  
Load Shedding ◽  
Load Management ◽  
Daily Maximum ◽  
Power Distribution Systems ◽  
Power Distribution System ◽  
Islanded Operation

The paper considers the possibilities of increasing the flexibility of power distribution systems by real-time load management. The principles of the implementation of special automatic systems for this purpose are proposed. These systems enable some loads of specific consumers of the power distribution system switched to islanded operation to “shift” from the daily maximum to the minimum, which makes some generators available to connect certain essential consumers disconnected earlier by under-frequency load shedding system to the power system. The approach under consideration is illustrated by a power system with distributed generation.

scholarly journals A Mixed Integer Linear Programming Based Load Shedding Technique for Improving the Sustainability of Islanded Distribution Systems

2020 ◽  
Vol 12 (15) ◽  
pp. 6234 ◽  
Author(s):  
Sohail Sarwar ◽  
Hazlie Mokhlis ◽  
Mohamadariff Othman ◽  
Munir Azam Muhammad ◽  
J. A. Laghari ◽  
...  
Keyword(s):  
Linear Programming ◽  
Integer Linear Programming ◽  
Distribution System ◽  
Mixed Integer Linear Programming ◽  
Distribution Systems ◽  
Voltage Stability ◽  
Stability Index ◽  
Load Shedding ◽  
Mixed Integer ◽  
System Frequency

In recent years significant changes in climate have pivoted the distribution system towards renewable energy, particularly through distributed generators (DGs). Although DGs offer many benefits to the distribution system, their integration affects the stability of the system, which could lead to blackout when the grid is disconnected. The system frequency will drop drastically if DG generation capacity is less than the total load demand in the network. In order to sustain the system stability, under-frequency load shedding (UFLS) is inevitable. The common approach of load shedding sheds random loads until the system’s frequency is recovered. Random and sequential selection results in excessive load shedding, which in turn causes frequency overshoot. In this regard, this paper proposes an efficient load shedding technique for islanded distribution systems. This technique utilizes a voltage stability index to rank the unstable loads for load shedding. In the proposed method, the power imbalance is computed using the swing equation incorporating frequency value. Mixed integer linear programming (MILP) optimization produces optimal load shedding strategy based on the priority of the loads (i.e., non-critical, semi-critical, and critical) and the load ranking from the voltage stability index of loads. The effectiveness of the proposed scheme is tested on two test systems, i.e., a 28-bus system that is a part of the Malaysian distribution network and the IEEE 69-bus system, using PSCAD/EMTDC. Results obtained prove the effectiveness of the proposed technique in quickly stabilizing the system’s frequency without frequency overshoot by disconnecting unstable non-critical loads on priority. Furthermore, results show that the proposed technique is superior to other adaptive techniques because it increases the sustainability by reducing the load shed amount and avoiding overshoot in system frequency.

scholarly journals Robust Stability Control for Electric Vehicles Connected to DC Distribution Systems

2021 ◽  
Vol 9 ◽  
Author(s):  
Wei Teng ◽  
Yuejiao Wang ◽  
Shumin Sun ◽  
Yan Cheng ◽  
Peng Yu ◽  
...  
Keyword(s):  
Electric Vehicles ◽  
Power Distribution ◽  
Distribution System ◽  
Distribution Systems ◽  
Voltage Stability ◽  
Stability Control ◽  
Power Distribution Systems ◽  
Power Distribution System ◽  
Dc Power ◽  
Dc Distribution

DC power distribution systems will play an important role in the future urban power distribution system, while the charging and discharging requirements of electric vehicles have a great impact on the voltage stability of the DC power distribution systems. A robust control method based on H∞ loop shaping method is proposed to suppress the effect of uncertain integration on voltage stability of DC distribution system. The results of frequency domain analysis and time domain simulation show that the proposed robust controller can effectively suppress the DC bus voltage oscillation caused by the uncertain integration of electric vehicle, and the robustness is strong.

scholarly journals Decentralized Load Shedding Method Based on Voltage Stability Margin Index Using Synchrophasor Measurement Technology

Electronics ◽  
2018 ◽  
Vol 7 (11) ◽  
pp. 277 ◽  
Author(s):  
Yunhwan Lee ◽  
Hwachang Song
Keyword(s):  
Power Systems ◽  
Voltage Stability ◽  
Stability Margin ◽  
Load Shedding ◽  
Measurement Technology ◽  
Dynamic Simulations ◽  
Stability Margins ◽  
Voltage Instability ◽  
Voltage Stability Margin ◽  
Simulation Results

This study develops an analytical method for assessing the voltage stability margins of a decentralized load shedding scheme; it then examines the challenges related to the existing load shedding scheme. It also presents a practical application for implementing the proposed method, based on the synchrophasor measurement technology in modern power grid operations. By applying the concept of a continuously-computed voltage stability margin index to the configuration of the Thévenin equivalent system, the maximum transfer power could be used as an index to monitor the voltage instability phenomenon and thus determine the required load shedding amount. Thus, the calculated voltage stability margin might be a useful index for system operators in the critical decision-making process of load shedding. Dynamic simulations are performed on real Korean power systems as case studies. Simulation results, when comparing the existing and proposed methods, showed that there was a considerable reduction in the amount of load shedding in the voltage instability scenario. This indicates that the synchrophasor measurement technology has a considerable effect on the proposed load shedding method. The simulation results have validated the performance of the proposed method.

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