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Special Issue "Electric Power Systems Research"

A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (15 January 2016)

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Guest Editor
Prof. Dr. Ying-Yi Hong

Department of Electrical Engineering, Chung Yuan Christian University, Taoyuan City, Taiwan
Website | E-Mail
Interests: smart grid; control and planning for microgrid; intelligent methods applied to power systems

Special Issue Information

Dear Colleagues,

The Edison Electric Light Company, owned by Thomas Edison, developed the first steam-based electric power station on Pearl Street in New York City in 1882. This power station initially supplied electric power to around 3000 lamps for 59 customers. This may have been the first power system in the world. At present, people request utilities to deliver electric power in a stable, reliable, secure and sustainable manner from a generation system through transmission and distribution systems to end-users. Consequently, the need to develop advanced technologies and novel methods applied to the modern power system is essential. Recently, the concept of smart grids incorporating renewables, power electronics-based facility and information/communication technology receives more and more attention. Research on smart grids must be also addressed.

Electric Power Systems Research is a Special Issue in Energies for those who would like to publish original papers about the generation, transmission, distribution and utilization of electrical energy. This Special Issue aims at presenting important results of work in power systems. Works can be applied research, development of new procedures or components, original application of existing knowledge, or new design approaches.

Papers in the relevant area of Electric Power Systems Research, including, but not limited to, the following, are invited:

  1. power system stability
  2. power system reliability
  3. facts applied to power systems
  4. optimization methods applied to power system studies
  5. architectures and models for smart grid
  6. power market
  7. control, operation and planning of distributed generation resources
  8. smart home with energy management systems
  9. microgrid and active distribution network
  10. virtual power plant and demand response

Prof. Dr. Ying-Yi Hong
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

 

Keywords

  • stability
  • reliability
  • optimization
  • sustainability

Related Special Issue

Published Papers (23 papers)

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Editorial

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Open AccessEditorial Electric Power Systems Research
Energies 2016, 9(10), 824; https://doi.org/10.3390/en9100824
Received: 3 October 2016 / Accepted: 11 October 2016 / Published: 15 October 2016
PDF Full-text (534 KB) | HTML Full-text | XML Full-text
Abstract
This book contains articles [1–22] that were accepted for publication in a Special Issue of Energies on the subject of “Electric Power Systems Research”.[...] Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Research

Jump to: Editorial, Review

Open AccessArticle Dynamic Equivalent Modeling for Small and Medium Hydropower Generator Group Based on Measurements
Energies 2016, 9(5), 362; https://doi.org/10.3390/en9050362
Received: 19 December 2015 / Revised: 26 April 2016 / Accepted: 5 May 2016 / Published: 12 May 2016
Cited by 4 | PDF Full-text (3074 KB) | HTML Full-text | XML Full-text
Abstract
At present, the common practice in the power system of China is to represent the small and medium hydropower generator group as a negative load. This paper presents a method to build a dynamic equivalent model of the hydropower generator group using a [...] Read more.
At present, the common practice in the power system of China is to represent the small and medium hydropower generator group as a negative load. This paper presents a method to build a dynamic equivalent model of the hydropower generator group using a 3rd order generator model and a static characteristic load model. Based on phasor measurements in the tie line which connects to the modeled hydropower generator group, the dynamic multi-swarm particle swarm optimizer (DMS-PSO) algorithm is used to obtain parameters of the equivalent model. The proposed method is verified in the small and medium hydropower generator group of Sichuan power grid with both simulation and actual data. The results show that the dynamic responses and the transient stability are consistent before and after the equivalence. The proposed method can be used for modeling a group of small and medium hydropower generators whose structures and parameters are unknown. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle Anti-Windup Load Frequency Controller Design for Multi-Area Power System with Generation Rate Constraint
Energies 2016, 9(5), 330; https://doi.org/10.3390/en9050330
Received: 25 December 2015 / Revised: 21 April 2016 / Accepted: 21 April 2016 / Published: 29 April 2016
Cited by 7 | PDF Full-text (4067 KB) | HTML Full-text | XML Full-text
Abstract
To deal with the problem of generation rate constraint (GRC) during load frequency control (LFC) design for a multi-area interconnected power system, this paper proposes an anti-windup controller design method. Firstly, an H dynamic controller is designed to obtain robust performance of [...] Read more.
To deal with the problem of generation rate constraint (GRC) during load frequency control (LFC) design for a multi-area interconnected power system, this paper proposes an anti-windup controller design method. Firstly, an H dynamic controller is designed to obtain robust performance of the closed-loop control system in the absence of the GRC. Then, an anti-windup compensator (AWC) is formulated to restrict the magnitude and rate of the control input (namely power increment) in the prescribed ranges so that the operation of generation unit does not exceed the physical constraints. Finally, the anti-windup LFC is tested on the multi-area interconnected power systems, and the simulation results illustrate the effectiveness of the proposed LFC design method with GRC. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle Interaction and Coordination among Nuclear Power Plants, Power Grids and Their Protection Systems
Energies 2016, 9(4), 306; https://doi.org/10.3390/en9040306
Received: 13 January 2016 / Revised: 30 March 2016 / Accepted: 5 April 2016 / Published: 21 April 2016
Cited by 3 | PDF Full-text (5527 KB) | HTML Full-text | XML Full-text
Abstract
Nuclear power plants (NPPs) have recently undergone rapid development in China. To improve the performance of both NPPs and grids during adverse conditions, a precise understanding of the coordination between NPPs and grids is required. Therefore, a new mathematical model with reasonable accuracy [...] Read more.
Nuclear power plants (NPPs) have recently undergone rapid development in China. To improve the performance of both NPPs and grids during adverse conditions, a precise understanding of the coordination between NPPs and grids is required. Therefore, a new mathematical model with reasonable accuracy and reduced computational complexity is developed. This model is applicable to the short, mid, and long-term dynamic simulation of large-scale power systems. The effectiveness of the model is verified by using an actual NPP full-scope simulator as a reference. Based on this model, the interaction and coordination between NPPs and grids under the conditions of over-frequency, under-frequency and under-voltage are analyzed, with special stress applied to the effect of protection systems on the safe operation of both NPPs and power grids. Finally, the coordinated control principles and schemes, together with the recommended protection system values, are proposed for both NPPs and grids. These results show that coordination between the protection systems of NPPs and power networks is a crucial factor in ensuring the safe and stable operation of both NPPs and grids. The results can be used as a reference for coordination between NPPs and grids, as well as for parameter optimization of grid-related generator protection of NPPs. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle A Time-Frequency Analysis Method for Low Frequency Oscillation Signals Using Resonance-Based Sparse Signal Decomposition and a Frequency Slice Wavelet Transform
Energies 2016, 9(3), 151; https://doi.org/10.3390/en9030151
Received: 5 December 2015 / Revised: 23 February 2016 / Accepted: 24 February 2016 / Published: 2 March 2016
Cited by 8 | PDF Full-text (4220 KB) | HTML Full-text | XML Full-text
Abstract
To more completely extract useful features from low frequency oscillation (LFO) signals, a time-frequency analysis method using resonance-based sparse signal decomposition (RSSD) and a frequency slice wavelet transform (FSWT) is proposed. FSWT can cut time-frequency areas freely, so that any band component feature [...] Read more.
To more completely extract useful features from low frequency oscillation (LFO) signals, a time-frequency analysis method using resonance-based sparse signal decomposition (RSSD) and a frequency slice wavelet transform (FSWT) is proposed. FSWT can cut time-frequency areas freely, so that any band component feature can be extracted. It can analyze multiple aspects of the LFO signal, including determination of dominant mode, mode seperation and extraction, and 3D map expression. Combined with the Hilbert transform,the parameters of the LFO mode components can be identified. Furthermore, the noise in the LFO signal could reduce the frequency resolution of FSWT analysis, which may impact the accuracy of oscillation mode identification. Complex signals can be separated by predictable Q-factors using RSSD. The RSSD method can do well in LFO signal denoising. Firstly, the LFO signal is decomposed into a high-resonance component, a low-resonance component and a residual by RSSD. The LFO signal is the output of an underdamped system with high quality factor and high-resonance property at a specific frequency. The high-resonance component is the denoised LFO signal, and the residual contains most of the noise. Secondly, the high-resonance component is decomposed by FSWT and the full band of its time-frequency distribution are obtained. The 3D map expression and dominant mode of the LFO can be obtained. After that, due to its energy distribution, frequency slices are chosen to get accurate analysis of time-frequency features. Through reconstructing signals in characteristic frequency slices, separation and extraction of the LFO mode components is realized. Thirdly, high-accuracy detection for modal parameter identification is achieved by the Hilbert transform. Simulation and application examples prove the effectiveness of the proposed method. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle A Co-Simulation Framework for Power System Analysis
Energies 2016, 9(3), 131; https://doi.org/10.3390/en9030131
Received: 16 November 2015 / Revised: 5 February 2016 / Accepted: 5 February 2016 / Published: 25 February 2016
Cited by 4 | PDF Full-text (5098 KB) | HTML Full-text | XML Full-text
Abstract
Power system electromagnetic transient (EMT) simulation has been used to study the electromagnetic behavior of power system components. It generally comprises detailed models of the study area and an equivalent circuit which represents an external part of the study area. However, a detailed [...] Read more.
Power system electromagnetic transient (EMT) simulation has been used to study the electromagnetic behavior of power system components. It generally comprises detailed models of the study area and an equivalent circuit which represents an external part of the study area. However, a detailed description of an external system that includes transmission or distribution system models is required to study the interaction among power system components because the number of high power converter based devices in a power grid have been increasing. Since detailed models of the system components are necessary to simulate a series of events such as cascading faults the computational burden of power system simulation has increased. Therefore a more effective and practical framework has been sought to handle this computational challenge. This paper proposes a co-simulation framework including a delay compensation algorithm to compensate the time delayed signals due to network segmentation and a fast and flexible simulation environment composed of non-real time power system EMT simulation on a general purpose computer with a multi core central processing unit (CPU), which is currently very popular owing to its performance. The proposed methods are applied to an AC/DC power system model. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle Field Experiments on 10 kV Switching Shunt Capacitor Banks Using Ordinary and Phase-Controlled Vacuum Circuit Breakers
Energies 2016, 9(2), 88; https://doi.org/10.3390/en9020088
Received: 17 December 2015 / Revised: 26 January 2016 / Accepted: 27 January 2016 / Published: 30 January 2016
Cited by 5 | PDF Full-text (5571 KB) | HTML Full-text | XML Full-text
Abstract
During the switching on/off of shunt capacitor banks in substations, vacuum circuit breakers (VCBs) are required to switch off or to switch on the capacitive current. Therefore, the VCBs have to be operated under a harsh condition to ensure the reliability of the [...] Read more.
During the switching on/off of shunt capacitor banks in substations, vacuum circuit breakers (VCBs) are required to switch off or to switch on the capacitive current. Therefore, the VCBs have to be operated under a harsh condition to ensure the reliability of the equipment. This study presents a complete comparison study of ordinary and phase-controlled VCBs on switching 10 kV shunt capacitor banks. An analytical analysis for switching 10 kV shunt capacitor banks is presented on the basis of a reduced circuit with an ungrounded neutral. A phase selection strategy for VCBs to switch 10 kV shunt capacitor banks is proposed. Switching on current waveforms and switching off overvoltage waveforms with, and without, phase selection were measured and discussed by field experiments in a 110 kV substation in Chongqing, China. Results show that the operation of phase-controlled VCBs for 10 kV switching shunt capacitor banks is stable, and phase-controlled VCBs can be used to implement the 10 kV switching on/off shunt capacitor banks to limit the transient overvoltage and overcurrent. The values of overvoltage and inrush current using phase-controlled VCBs are all below those with ordinary VCBs. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle Multi-Objective Demand Response Model Considering the Probabilistic Characteristic of Price Elastic Load
Energies 2016, 9(2), 80; https://doi.org/10.3390/en9020080
Received: 30 November 2015 / Revised: 4 January 2016 / Accepted: 18 January 2016 / Published: 27 January 2016
Cited by 9 | PDF Full-text (1109 KB) | HTML Full-text | XML Full-text
Abstract
Demand response (DR) programs provide an effective approach for dealing with the challenge of wind power output fluctuations. Given that uncertain DR, such as price elastic load (PEL), plays an important role, the uncertainty of demand response behavior must be studied. In this [...] Read more.
Demand response (DR) programs provide an effective approach for dealing with the challenge of wind power output fluctuations. Given that uncertain DR, such as price elastic load (PEL), plays an important role, the uncertainty of demand response behavior must be studied. In this paper, a multi-objective stochastic optimization problem of PEL is proposed on the basis of the analysis of the relationship between price elasticity and probabilistic characteristic, which is about stochastic demand models for consumer loads. The analysis aims to improve the capability of accommodating wind output uncertainty. In our approach, the relationship between the amount of demand response and interaction efficiency is developed by actively participating in power grid interaction. The probabilistic representation and uncertainty range of the PEL demand response amount are formulated differently compared with those of previous research. Based on the aforementioned findings, a stochastic optimization model with the combined uncertainties from the wind power output and the demand response scenario is proposed. The proposed model analyzes the demand response behavior of PEL by maximizing the electricity consumption satisfaction and interaction benefit satisfaction of PEL. Finally, a case simulation on the provincial power grid with a 151-bus system verifies the effectiveness and feasibility of the proposed mechanism and models. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle A Study on Maximum Wind Power Penetration Limit in Island Power System Considering High-Voltage Direct Current Interconnections
Energies 2015, 8(12), 14244-14259; https://doi.org/10.3390/en81212425
Received: 7 September 2015 / Revised: 27 November 2015 / Accepted: 7 December 2015 / Published: 17 December 2015
Cited by 10 | PDF Full-text (2313 KB) | HTML Full-text | XML Full-text
Abstract
The variability and uncontrollability of wind power increases the difficulty for a power system operator to implement a wind power system with a high penetration rate. These are more serious factors to consider in small and isolated power systems since the system has [...] Read more.
The variability and uncontrollability of wind power increases the difficulty for a power system operator to implement a wind power system with a high penetration rate. These are more serious factors to consider in small and isolated power systems since the system has small operating reserves and inertia to secure frequency and voltage. Typically, this difficulty can be reduced by interconnection with another robust power system using a controllable transmission system such as a high-voltage direct current (HVDC) system. However, the reliability and stability constraints of a power system has to be performed according to the HVDC system implementation. In this paper, the method for calculation of maximum wind power penetration in an island supplied by a HVDC power system is presented, and the operational strategy of a HVDC system is proposed to secure the power system reliability and stability. The case study is performed for the Jeju Island power system in the Korean smart grid demonstration area. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle Designing an Incentive Contract Menu for Sustaining the Electricity Market
Energies 2015, 8(12), 14197-14218; https://doi.org/10.3390/en81212419
Received: 14 October 2015 / Revised: 4 December 2015 / Accepted: 7 December 2015 / Published: 16 December 2015
Cited by 3 | PDF Full-text (2231 KB) | HTML Full-text | XML Full-text
Abstract
This paper designs an incentive contract menu to achieve long-term stability for electricity prices in a day-ahead electricity market. A bi-level Stackelberg game model is proposed to search for the optimal incentive mechanism under a one-leader and multi-followers gaming framework. A multi-agent simulation [...] Read more.
This paper designs an incentive contract menu to achieve long-term stability for electricity prices in a day-ahead electricity market. A bi-level Stackelberg game model is proposed to search for the optimal incentive mechanism under a one-leader and multi-followers gaming framework. A multi-agent simulation platform was developed to investigate the effectiveness of the incentive mechanism using an independent system operator (ISO) and multiple power generating companies (GenCos). Further, a Q-learning approach was implemented to analyze and assess the response of GenCos to the incentive menu. Numerical examples are provided to demonstrate the effectiveness of the incentive contract. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle Voltage Control Method Using Distributed Generators Based on a Multi-Agent System
Energies 2015, 8(12), 14009-14025; https://doi.org/10.3390/en81212411
Received: 21 September 2015 / Revised: 22 November 2015 / Accepted: 3 December 2015 / Published: 11 December 2015
Cited by 9 | PDF Full-text (879 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a voltage control method using multiple distributed generators (DGs) based on a multi-agent system framework. The output controller of each DG is represented as a DG agent, and each voltage-monitoring device is represented as a monitoring agent. These agents cooperate [...] Read more.
This paper presents a voltage control method using multiple distributed generators (DGs) based on a multi-agent system framework. The output controller of each DG is represented as a DG agent, and each voltage-monitoring device is represented as a monitoring agent. These agents cooperate to accomplish voltage regulation through a coordinating agent or moderator. The moderator uses the reactive power sensitivities and margins to determine the voltage control contributions of each DG. A fuzzy inference system (FIS) is employed by the moderator to manage the decision-making process. An FIS scheme is developed and optimized to enhance the efficiency of the proposed voltage control process using particle swarm optimization. A simple distribution system with four voltage-controllable DGs is modeled, and an FIS moderator is implemented to control the system. Simulated data show that the proposed voltage control process is able to maintain the system within the operating voltage limits. Furthermore, the results were similar to those obtained using optimal power flow calculations, even though little information on the power system was required and no power flow calculations were implemented. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle A Two-stage Optimal Network Reconfiguration Approach for Minimizing Energy Loss of Distribution Networks Using Particle Swarm Optimization Algorithm
Energies 2015, 8(12), 13894-13910; https://doi.org/10.3390/en81212402
Received: 7 October 2015 / Accepted: 1 December 2015 / Published: 5 December 2015
Cited by 5 | PDF Full-text (2794 KB) | HTML Full-text | XML Full-text
Abstract
This study aimed to minimize energy losses in traditional distribution networks and microgrids through a network reconfiguration and phase balancing approach. To address this problem, an algorithm composed of a multi-objective function and operation constraints is proposed. Network connection matrices based on graph [...] Read more.
This study aimed to minimize energy losses in traditional distribution networks and microgrids through a network reconfiguration and phase balancing approach. To address this problem, an algorithm composed of a multi-objective function and operation constraints is proposed. Network connection matrices based on graph theory and the backward/forward sweep method are used to analyze power flow. A minimizing energy loss approach is developed for network reconfiguration and phase balancing, and the particle swarm optimization (PSO) algorithm is adopted to solve this optimal combination problem. The proposed approach is tested on the IEEE 37-bus test system and the first outdoor microgrid test bed established by the Institute of Nuclear Energy Research (INER) in Taiwan. Simulation results demonstrate that the proposed two-stage approach can be applied in network reconfiguration to minimize energy loss. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle Comparison between IEEE and CIGRE Thermal Behaviour Standards and Measured Temperature on a 132-kV Overhead Power Line
Energies 2015, 8(12), 13660-13671; https://doi.org/10.3390/en81212391
Received: 6 July 2015 / Revised: 19 November 2015 / Accepted: 19 November 2015 / Published: 2 December 2015
Cited by 20 | PDF Full-text (12389 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the steady and dynamic thermal balances of an overhead power line proposed by CIGRE (Technical Brochure 601, 2014) and IEEE (Std.738, 2012) standards. The estimated temperatures calculated by the standards are compared with the averaged conductor temperature obtained every 8 [...] Read more.
This paper presents the steady and dynamic thermal balances of an overhead power line proposed by CIGRE (Technical Brochure 601, 2014) and IEEE (Std.738, 2012) standards. The estimated temperatures calculated by the standards are compared with the averaged conductor temperature obtained every 8 min during a year. The conductor is a LA 280 Hawk type, used in a 132-kV overhead line. The steady and dynamic state comparison shows that the number of cases with deviations to conductor temperatures higher than 5 ∘ C decreases from around 20% to 15% when the dynamic analysis is used. As some of the most critical variables are magnitude and direction of the wind speed, ambient temperature and solar radiation, their influence on the conductor temperature is studied. Both standards give similar results with slight differences due to the different way to calculate the solar radiation and convection. Considering the wind, both standards provide better results for the estimated conductor temperature as the wind speed increases and the angle with the line is closer to 90 ∘ . In addition, if the theoretical radiation is replaced by that measured with the pyranometer, the number of samples with deviations higher than 5 ∘ C is reduced from around 15% to 5%. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle Response Based Emergency Control System for Power System Transient Stability
Energies 2015, 8(12), 13508-13520; https://doi.org/10.3390/en81212381
Received: 8 August 2015 / Revised: 11 November 2015 / Accepted: 13 November 2015 / Published: 30 November 2015
Cited by 5 | PDF Full-text (1834 KB) | HTML Full-text | XML Full-text
Abstract
A transient stability control system for the electric power system composed of a prediction method and a control method is proposed based on trajectory information. This system, which is independent of system parameters and models, can detect the transient stability of the electric [...] Read more.
A transient stability control system for the electric power system composed of a prediction method and a control method is proposed based on trajectory information. This system, which is independent of system parameters and models, can detect the transient stability of the electric power system quickly and provide the control law when the system is unstable. Firstly, system instability is detected by the characteristic concave or convex shape of the trajectory. Secondly, the control method is proposed based on the analysis of the slope of the state plane trajectory when the power system is unstable. Two control objectives are provided according to the methods of acquiring the far end point: one is the minimal cost to restore the system to a stable state; the other one is the minimal cost to limit the maximum swing angle. The simulation indicates that the mentioned transient stability control system is efficient. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle General Dynamic Equivalent Modeling of Microgrid Based on Physical Background
Energies 2015, 8(11), 12929-12948; https://doi.org/10.3390/en81112354
Received: 17 September 2015 / Revised: 14 October 2015 / Accepted: 9 November 2015 / Published: 17 November 2015
Cited by 8 | PDF Full-text (3407 KB) | HTML Full-text | XML Full-text
Abstract
Microgrid is a new power system concept consisting of small-scale distributed energy resources; storage devices and loads. It is necessary to employ a simplified model of microgrid in the simulation of a distribution network integrating large-scale microgrids. Based on the detailed model of [...] Read more.
Microgrid is a new power system concept consisting of small-scale distributed energy resources; storage devices and loads. It is necessary to employ a simplified model of microgrid in the simulation of a distribution network integrating large-scale microgrids. Based on the detailed model of the components, an equivalent model of microgrid is proposed in this paper. The equivalent model comprises two parts: namely, equivalent machine component and equivalent static component. Equivalent machine component describes the dynamics of synchronous generator, asynchronous wind turbine and induction motor, equivalent static component describes the dynamics of photovoltaic, storage and static load. The trajectory sensitivities of the equivalent model parameters with respect to the output variables are analyzed. The key parameters that play important roles in the dynamics of the output variables of the equivalent model are identified and included in further parameter estimation. Particle Swarm Optimization (PSO) is improved for the parameter estimation of the equivalent model. Simulations are performed in different microgrid operation conditions to evaluate the effectiveness of the equivalent model of microgrid. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle An Analysis of Decentralized Demand Response as Frequency Control Support under CriticalWind Power Oscillations
Energies 2015, 8(11), 12881-12897; https://doi.org/10.3390/en81112349
Received: 4 September 2015 / Revised: 28 October 2015 / Accepted: 4 November 2015 / Published: 13 November 2015
Cited by 4 | PDF Full-text (1671 KB) | HTML Full-text | XML Full-text
Abstract
In power systems with high wind energy penetration, the conjunction of wind power fluctuations and power system inertia reduction can lead to large frequency excursions, where the operating reserves of conventional power generation may be insufficient to restore the power balance. With the [...] Read more.
In power systems with high wind energy penetration, the conjunction of wind power fluctuations and power system inertia reduction can lead to large frequency excursions, where the operating reserves of conventional power generation may be insufficient to restore the power balance. With the aim of evaluating the demand-side contribution to frequency control, a complete process to determine critical wind oscillations in power systems with high wind penetration is discussed and described in this paper. This process implies thousands of wind power series simulations, which have been carried out through a validated offshore wind farm model. A large number of different conditions have been taken into account, such as frequency dead bands, the percentages of controllable demand and seasonal factor influence on controllable loads. Relevant results and statistics are also included in the paper. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle Modeling and Optimization of the Medium-Term Units Commitment of Thermal Power
Energies 2015, 8(11), 12848-12864; https://doi.org/10.3390/en81112345
Received: 25 September 2015 / Revised: 30 October 2015 / Accepted: 4 November 2015 / Published: 12 November 2015
Cited by 6 | PDF Full-text (2302 KB) | HTML Full-text | XML Full-text
Abstract
Coal-fired thermal power plants, which represent the largest proportion of China’s electric power system, are very sluggish in responding to power system load demands. Thus, a reasonable and feasible scheme for the medium-term optimal commitment of thermal units (MOCTU) can ensure that the [...] Read more.
Coal-fired thermal power plants, which represent the largest proportion of China’s electric power system, are very sluggish in responding to power system load demands. Thus, a reasonable and feasible scheme for the medium-term optimal commitment of thermal units (MOCTU) can ensure that the generation process runs smoothly and minimizes the start-up and shut-down times of thermal units. In this paper, based on the real-world and practical demands of power dispatch centers in China, a flexible mathematical model for MOCTU that uses equal utilization hours for the installed capacity of all thermal power plants as the optimization goal and that considers the award hours for MOCTU is developed. MOCTU is a unit commitment (UC) problem with characteristics of large-scale, high dimensions and nonlinearity. For optimization, an improved progressive optimality algorithm (IPOA) offering the advantages of POA is adopted to overcome the drawback of POA of easily falling into the local optima. In the optimization process, strategies of system operating capacity equalization and single station operating peak combination are introduced to move the target solution from the boundary constraints along the target isopleths into the feasible solution’s interior to guarantee the global optima. The results of a case study consisting of nine thermal power plants with 27 units show that the presented algorithm can obtain an optimal solution and is competent in solving the MOCTU with high efficiency and accuracy as well as that the developed simulation model can be applied to practical engineering needs. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle Optimal Subinterval Selection Approach for Power System Transient Stability Simulation
Energies 2015, 8(10), 11871-11882; https://doi.org/10.3390/en81011871
Received: 2 September 2015 / Revised: 14 October 2015 / Accepted: 16 October 2015 / Published: 21 October 2015
Cited by 2 | PDF Full-text (333 KB) | HTML Full-text | XML Full-text
Abstract
Power system transient stability analysis requires an appropriate integration time step to avoid numerical instability as well as to reduce computational demands. For fast system dynamics, which vary more rapidly than what the time step covers, a fraction of the time step, called [...] Read more.
Power system transient stability analysis requires an appropriate integration time step to avoid numerical instability as well as to reduce computational demands. For fast system dynamics, which vary more rapidly than what the time step covers, a fraction of the time step, called a subinterval, is used. However, the optimal value of this subinterval is not easily determined because the analysis of the system dynamics might be required. This selection is usually made from engineering experiences, and perhaps trial and error. This paper proposes an optimal subinterval selection approach for power system transient stability analysis, which is based on modal analysis using a single machine infinite bus (SMIB) system. Fast system dynamics are identified with the modal analysis and the SMIB system is used focusing on fast local modes. An appropriate subinterval time step from the proposed approach can reduce computational burden and achieve accurate simulation responses as well. The performance of the proposed method is demonstrated with the GSO 37-bus system. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle Designing a Profit-Maximizing Critical Peak Pricing Scheme Considering the Payback Phenomenon
Energies 2015, 8(10), 11363-11379; https://doi.org/10.3390/en81011363
Received: 15 July 2015 / Revised: 4 October 2015 / Accepted: 8 October 2015 / Published: 13 October 2015
Cited by 7 | PDF Full-text (443 KB) | HTML Full-text | XML Full-text
Abstract
Critical peak pricing (CPP) is a demand response program that can be used to maximize profits for a load serving entity in a deregulated market environment. Like other such programs, however, CPP is not free from the payback phenomenon: a rise in consumption [...] Read more.
Critical peak pricing (CPP) is a demand response program that can be used to maximize profits for a load serving entity in a deregulated market environment. Like other such programs, however, CPP is not free from the payback phenomenon: a rise in consumption after a critical event. This payback has a negative effect on profits and thus must be appropriately considered when designing a CPP scheme. However, few studies have examined CPP scheme design considering payback. This study thus characterizes payback using three parameters (duration, amount, and pattern) and examines payback effects on the optimal schedule of critical events and on the optimal peak rate for two specific payback patterns. This analysis is verified through numerical simulations. The results demonstrate the need to properly consider payback parameters when designing a profit-maximizing CPP scheme. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle Active Participation of Air Conditioners in Power System Frequency Control Considering Users’ Thermal Comfort
Energies 2015, 8(10), 10818-10841; https://doi.org/10.3390/en81010818
Received: 21 August 2015 / Revised: 20 September 2015 / Accepted: 21 September 2015 / Published: 28 September 2015
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Abstract
Air conditioners have great potential to participate in power system frequency control. This paper proposes a control strategy to facilitate the active participation of air conditioners. For each air conditioner, a decentralized control law is designed to adjust its temperature set point in [...] Read more.
Air conditioners have great potential to participate in power system frequency control. This paper proposes a control strategy to facilitate the active participation of air conditioners. For each air conditioner, a decentralized control law is designed to adjust its temperature set point in response to the system frequency deviation. The decentralized control law accounts for the user’s thermal comfort that is evaluated by a fuzzy algorithm. The aggregation of air conditioners’ response is conducted by using the Monte Carlo simulation method. A structure preserving model is applied to the multi-bus power system, in which air conditioners are aggregated at certain load buses. An inner-outer iteration scheme is adopted to solve power system dynamics. An experiment is conducted on a test air conditioner to examine the performance of the proposed decentralized control law. Simulation results on a test power system verify the effectiveness of the proposed strategy for air conditioners participating in frequency control. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle A Two-Stage Algorithm to Estimate the Fundamental Frequency of Asynchronously Sampled Signals in Power Systems
Energies 2015, 8(9), 9282-9295; https://doi.org/10.3390/en8099282
Received: 9 July 2015 / Revised: 19 August 2015 / Accepted: 21 August 2015 / Published: 28 August 2015
Cited by 2 | PDF Full-text (499 KB) | HTML Full-text | XML Full-text
Abstract
A two-stage algorithm is proposed for the estimation of the fundamental frequency of asynchronously sampled signals in power systems. In the first stage, time-domain interpolation reconstructs the power system signal at a new sampling time and the reconstructed signal passes through a tuned [...] Read more.
A two-stage algorithm is proposed for the estimation of the fundamental frequency of asynchronously sampled signals in power systems. In the first stage, time-domain interpolation reconstructs the power system signal at a new sampling time and the reconstructed signal passes through a tuned sine filter to eliminate harmonics. In the second stage, the fundamental frequency is estimated using a modified curve fitting, which is robust to noise. The evaluation results confirm the efficiency and validity of the two-stage algorithm for accurate estimation of the fundamental frequency even for asynchronously sampled signals contaminated with noise, harmonics, and an inter-harmonic component. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessArticle Interval Type-II Fuzzy Rule-Based STATCOM for Voltage Regulation in the Power System
Energies 2015, 8(8), 8908-8923; https://doi.org/10.3390/en8088908
Received: 9 July 2015 / Revised: 6 August 2015 / Accepted: 17 August 2015 / Published: 21 August 2015
Cited by 3 | PDF Full-text (455 KB) | HTML Full-text | XML Full-text
Abstract
The static synchronous compensator (STATCOM) has recently received much attention owing to its ability to stabilize power systems and mitigate voltage variations. This paper investigates a novel interval type-II fuzzy rule-based PID (proportional-integral-derivative) controller for the STATCOM to mitigate bus voltage [...] Read more.
The static synchronous compensator (STATCOM) has recently received much attention owing to its ability to stabilize power systems and mitigate voltage variations. This paper investigates a novel interval type-II fuzzy rule-based PID (proportional-integral-derivative) controller for the STATCOM to mitigate bus voltage variations caused by large changes in load and the intermittent generation of photovoltaic (PV) arrays. The proposed interval type-II fuzzy rule base utilizes the output of the PID controller to tune the signal applied to the STATCOM. The rules involve upper and lower membership functions that ensure the stable responses of the controlled system. The proposed method is implemented using the NEPLAN software package and MATLAB/Simulink with co-simulation. A six-bus system is used to show the effectiveness of the proposed method. Comparative studies show that the proposed method is superior to traditional PID and type-I fuzzy rule-based methods. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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Open AccessFeature PaperEditor’s ChoiceReview Smart Distribution Systems
Energies 2016, 9(4), 297; https://doi.org/10.3390/en9040297
Received: 6 March 2016 / Revised: 1 April 2016 / Accepted: 11 April 2016 / Published: 19 April 2016
Cited by 7 | PDF Full-text (1827 KB) | HTML Full-text | XML Full-text
Abstract
The increasing importance of system reliability and resilience is changing the way distribution systems are planned and operated. To achieve a distribution system self-healing against power outages, emerging technologies and devices, such as remote-controlled switches (RCSs) and smart meters, are being deployed. The [...] Read more.
The increasing importance of system reliability and resilience is changing the way distribution systems are planned and operated. To achieve a distribution system self-healing against power outages, emerging technologies and devices, such as remote-controlled switches (RCSs) and smart meters, are being deployed. The higher level of automation is transforming traditional distribution systems into the smart distribution systems (SDSs) of the future. The availability of data and remote control capability in SDSs provides distribution operators with an opportunity to optimize system operation and control. In this paper, the development of SDSs and resulting benefits of enhanced system capabilities are discussed. A comprehensive survey is conducted on the state-of-the-art applications of RCSs and smart meters in SDSs. Specifically, a new method, called Temporal Causal Diagram (TCD), is used to incorporate outage notifications from smart meters for enhanced outage management. To fully utilize the fast operation of RCSs, the spanning tree search algorithm is used to develop service restoration strategies. Optimal placement of RCSs and the resulting enhancement of system reliability are discussed. Distribution system resilience with respect to extreme events is presented. Test cases are used to demonstrate the benefit of SDSs. Active management of distributed generators (DGs) is introduced. Future research in a smart distribution environment is proposed. Full article
(This article belongs to the Special Issue Electric Power Systems Research) Printed Edition available
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