Effective Demand Side Scheme for PHEVs Operation Considering Voltage Stability of Power Distribution Systems

2017 ◽  
Vol 18 (2) ◽  
Author(s):  
Mamdouh Abdel-Akher ◽  
Ahmad Eid ◽  
Abdelfatah Ali
Keyword(s):  
Control Strategy ◽  
Power Distribution ◽  
Distribution System ◽  
Distribution Systems ◽  
Voltage Stability ◽  
Fuzzy Logic Controller ◽  
Control Method ◽  
Stability Index ◽  
Input Variables ◽  
Network Status

Abstract This paper presents a new technique for a controlled charging/discharging of the PHEV’s battery considering the network status on a real-time basis. A control strategy is developed to secure the operation of power system irrespective of the number of vehicles and their connection place. The proposed control strategy utilizes an improved normalized steady-state voltage stability index that is easy to compute in the distribution management systems. A fuzzy logic controller (FLC) is used for evaluating the battery level of charging/discharging of individual PHEV connected to the distribution network. The controller is a part of the smart charger which uses the battery state of charge and the stability index as input variables. Based on the FLC output, the interface converter of a PHEV decides the desired charging/discharging levels of the battery. The developed controller ensures the secure operation of the distribution system during charging since only empty batteries will have a high priority to charge. A time domain, as well as 24-hour time-series simulations, are used to test the proposed control method. The results show that the developed control method guarantees secure operation, whatever the number and location of PHEVs connected to the studied system.

A Novel Control Strategy for Three-Phase Four-Wire STATCOM

2012 ◽  
Vol 516-517 ◽  
pp. 1722-1727 ◽  
Author(s):  
Wei Jun Yun ◽  
Gang Yao ◽  
Li Dan Zhou ◽  
Chen Chen ◽  
Jun Min Pan
Keyword(s):  
Control Strategy ◽  
Power Distribution ◽  
Distribution System ◽  
Reactive Power ◽  
Control Method ◽  
Loop Control ◽  
Power Distribution System ◽  
Imbalance Problem ◽  
Three Phase ◽  
Close Loop Control

Nowadays Static Synchronous Compensator (STATCOM) has gradually become one of the representative techniques in the field of dynamic reactive power compensation in the power distribution system. This paper analyzed the topology and the voltage imbalance problem of the up and down capacitors on DC side of the three-phase four-wire STATCOM. In allusion to the imbalance problem of neutral point, a novel control strategy based on the control of zero-sequence current was proposed. By the triple close-loop control strategy, the STATCOM can achieve great control accuracy and dynamic performance. Simulation result proves that the proposed control method is effective.

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.

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 Optimal Control Strategy for Distributed Energy Resources in a DC Microgrid for Energy Cost Reduction and Voltage Regulation

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 992
Author(s):  
Phi-Hai Trinh ◽  
Il-Yop Chung
Keyword(s):  
Control Strategy ◽  
Distribution System ◽  
Distribution Systems ◽  
Control Method ◽  
Voltage Regulation ◽  
Energy Resources ◽  
Distributed Energy Resources ◽  
Sensitivity Factor ◽  
Voltage Sensitivity ◽  
Distributed Energy

Distributed energy resources (DERs), including renewable energy resources (RESs) and electric vehicles (EVs), have a significant impact on distribution systems because they can cause bi-directional power flow in the distribution lines. Thus, the voltage regulation and thermal limits of the distribution system to mitigate from the excessive power generation or consumption should be considered. The focus of this study is on a control strategy for DERs in low-voltage DC microgrids to minimize the operating costs and maintain the distribution voltage within the normal range based on intelligent scheduling of the charging and discharging of EVs, and to take advantage of RESs such as photovoltaic (PV) plants. By considering the time-of-use electricity rates, we also propose a 24-h sliding window to mitigate uncertainties in loads and PV plants in which the output is time-varied and the EV arrival cannot be predicted. After obtaining a request from the EV owner, the proposed optimal DER control method satisfies the state-of-charge level for their next journey. We applied the voltage sensitivity factor obtained from a load-flow analysis to effectively maintain voltage profiles for the overall DC distribution system. The performance of the proposed optimal DER control method was evaluated with case studies and by comparison with conventional methods.

scholarly journals Application of Fuzzy Controller for Improvement of Power Quality using UPQC

2020 ◽  
pp. 27-30
Author(s):  
Kundeti Krishna Rao , M Sonia
Keyword(s):  
Power Quality ◽  
Power Distribution ◽  
Distribution System ◽  
Distribution Systems ◽  
Fuzzy Logic Controller ◽  
Fuzzy Controller ◽  
Active Filters ◽  
Voltage Source ◽  
Shunt Active Filter ◽  
Power Distribution System

Generally, one of the custom power device in FACTS called unified power quality conditioner, which is used to compensate the voltage and current-related Power Quality issues in the distribution systems. The proposed UPQC technology have an advantage of reduced dc-link voltage without compromising its compensation capability. This new method also helps to meet the requirement of dc-link voltage for the shunt and series active filters of the UPQC. This type of topology has a capacitor in series with the interfacing inductor across the shunt active filter for filtering purpose, and the system neutral is also considered and directly connected to neutral of distribution system avoid the requirement of the fourth leg in the voltage source inverter. This paper also presents a concept for improving power quality of a power distribution system such as an FUZZY logic controller along with the UPQC control strategy. The simulation results are compared for both conventional PI controller and FUZZY controller.

scholarly journals Voltage Stability of Low-Voltage Distribution Grid with High Penetration of Photovoltaic Power Units

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1960 ◽  
Author(s):  
Majid Ghaffarianfar ◽  
Amin Hajizadeh
Keyword(s):  
Power Distribution ◽  
Distribution System ◽  
Distribution Systems ◽  
Voltage Stability ◽  
Low Voltage ◽  
Distribution Networks ◽  
High Ratio ◽  
Distribution Grid ◽  
Negative Effects ◽  
Loss Analysis

Voltage stability analysis of power distribution systems with high photovoltaic (PV) penetration is a challenging problem due to the stochastic generation of a solar power system. Voltage stability is an important benchmark for defining PV’s penetration level in active distribution networks considering loading capacity. The massive integration of PV power units, the effect of distribution system characteristics, like high ratio of R/X, and the reported collapses in power networks come up in serious studies that investigate their impact and upcoming problems on distribution networks. Therefore, this paper proposes analytical voltage stability and it is implemented on IEEE 34 nodes radial distribution systems with 24.9 kV and 4.16 kV voltage levels. In this regard, in addition to given properties in stability and power loss analysis, a penetration coefficient for PVs is considered. Simulation results prove that the applied method can illustrate the positive and negative effects of PV in distribution networks.

Sign in / Sign up

Export Citation Format

Share Document