Special Issue "Electric Power Systems Research 2018"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "Electrical Power and Energy System".

Deadline for manuscript submissions: closed (31 December 2018).

Special Issue Editor

Prof. Dr. Ying-Yi Hong
E-Mail Website
Guest Editor
Department of Electrical Engineering, Chung Yuan Christian University, Taoyuan City 32023, Taiwan
Interests: smart grid; control and planning for microgrid; intelligent methods applied to power systems
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Ensuring a sustainable power delivery from generation system through transmission and distribution systems to end-users is a main responsibility in a power grid utility. A power grid is a large-scale and nonlinear system, which has a latent scecurity, stablility or reliablility problem. As a consequence, development of advanced technologies and novel methods applied to the modern power system is crucial.  Especially, distributed generation resources, energy storage system, electric vehicle, advanced device, demand response program, power market and power quality are addressed in a modern smart power system.

Electric Power Systems Research is a special issue in Energies for those who would like to publish the original papers about the generation, transmission, distribution and utilization of electrical energy. This special issue aims at presenting important results of work in the electric power systems.  The works can be applied research, development of new algorithms or components, original application of existing knowledge or new facilities applied to power systems. This special issue received much attention in 2016 and 2017 and published many state-of-art works, too

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. Power System Optimization
  5. Intelligent Methods Applied to Power System Studies
  6. Power Market and Demand Response Program
  7. Control of Generation Systems
  8. Operation of Distribution Systems
  9. Control, Operation and Planning of Distributed Generation Resources
  10. Control, Operation and Planning of Energy Storage System and Electric Vehicle
  11. Smart Community with Energy Management Systems
  12. Microgrid and Virtual Power Plant
  13. Active Distribution Network
  14. Harmonics/Voltage Power Quality
Prof. Dr. Ying-Yi Hong
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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 2000 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
  • sustainability
  • security

Published Papers (16 papers)

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Research

Open AccessArticle
An Innovative Calibration Scheme for Interharmonic Analyzers in Power Systems under Asynchronous Sampling
Energies 2019, 12(1), 121; https://doi.org/10.3390/en12010121 - 30 Dec 2018
Cited by 3 | Viewed by 957
Abstract
Power-quality analyzers are commonly used in power systems to estimate waveform distortion, including the parameters of harmonics/interharmonics. In our study, a calibration scheme was developed and verified. This scheme is capable of calibrating the interharmonics specification of power-quality analyzers under asynchronous sampling. In [...] Read more.
Power-quality analyzers are commonly used in power systems to estimate waveform distortion, including the parameters of harmonics/interharmonics. In our study, a calibration scheme was developed and verified. This scheme is capable of calibrating the interharmonics specification of power-quality analyzers under asynchronous sampling. In our scheme, the hardware structure is composed of an interharmonic signal source, a wide-frequency resistive voltage divider, a broadband current shunt, and a data acquisition system. A new algorithm, based on discrete Fourier transform and interpolation, is presented. The procedure is implemented by LabVIEW software to process the sampling data and obtain the final interharmonic parameters. The test results of the amplitudes of the interharmonic current and voltage indicate that the calibration accuracy is 3.0‰ (16 Hz–6 kHz) and 6.8‰ (6 kHz–9 kHz) for the voltage signal, and 3.5‰ (16 Hz–6 kHz) and 6.5‰ (6 kHz–9 kHz) for the current signal. This index is higher than that acquired by the recommended methods in the International Electrotechnical Commission (IEC) standard. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
Robust Load Frequency Control Schemes in Power System Using Optimized PID and Model Predictive Controllers
Energies 2018, 11(11), 3070; https://doi.org/10.3390/en11113070 - 07 Nov 2018
Cited by 8 | Viewed by 1229
Abstract
Robust control methodology for two-area load frequency control model is proposed in this paper. The paper presents a comparative study between the performance of model predictive controller (MPC) and optimized proportional–integral–derivative (PID) controller on different systems. An objective function derived from settling time, [...] Read more.
Robust control methodology for two-area load frequency control model is proposed in this paper. The paper presents a comparative study between the performance of model predictive controller (MPC) and optimized proportional–integral–derivative (PID) controller on different systems. An objective function derived from settling time, percentage overshoot and percentage undershoot is minimized to obtain the gains of the PID controller. Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) are used to tune the parameters of the PID controller through performance optimization of the system. System performance characteristics were compared to another controller designed based on MPC. Detailed comparison was performed between the performances of the MPC and optimized PID. The effectiveness and robustness of the proposed schemes were verified by the numerical simulation in MATLAB environment under different scenarios such as load and parameters variations. Moreover, the pole-zero map of each proposed approach is presented to investigate their stability. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
A Simple Method for Reducing THD and Improving the Efficiency in CSI Topology Based on SiC Power Devices
Energies 2018, 11(10), 2798; https://doi.org/10.3390/en11102798 - 17 Oct 2018
Cited by 10 | Viewed by 1378
Abstract
Silicon carbide (SiC)-based switching devices provide significant performance improvements in many aspects, including lower power dissipation, higher operating temperatures, and faster switching; compared with conventional Si devices, all these features contribute to these devices generating interest in applications for electric traction systems. The [...] Read more.
Silicon carbide (SiC)-based switching devices provide significant performance improvements in many aspects, including lower power dissipation, higher operating temperatures, and faster switching; compared with conventional Si devices, all these features contribute to these devices generating interest in applications for electric traction systems. The topology that is frequently used in these systems is the voltage source inverter (VSI), but the use of SiC devices in the current source inverter topology (CSI), which is considered as an emerging topology, generates interest. This paper presents a method for improving total harmonic distortion (THD) in the currents of output and efficiency in SiC current source inverter for future application in an electric traction system. The method that is proposed consists of improving the coupling of a bidirectional converter topology, voltage current (V-I) and CSI. The V-I converter serves as a current regulator for the CSI, and allows for the recovery of energy. The method involves an effective selection of the switching frequencies and phase angles for the carrier signals that are present in each converter topology. With this method, it is expected to have a reduction of the total harmonic distortion, THD in the output currents. In addition, a comparative analysis between converters with all-SiC technology and converters with hybrid technology is realized, to verify the impact of the SiC devices in the power converters efficiency. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
Transmission Expansion Planning under Uncertainty for Investment Options with Various Lead-Times
Energies 2018, 11(9), 2429; https://doi.org/10.3390/en11092429 - 13 Sep 2018
Cited by 6 | Viewed by 1133
Abstract
Investment options of transmission expansion planning (TEP) involve different lead times according to their length, technology, and environmental and social impacts. TEP planners can utilize the various lead times to deal with the risk of uncertainty. This paper proposes a novel framework for [...] Read more.
Investment options of transmission expansion planning (TEP) involve different lead times according to their length, technology, and environmental and social impacts. TEP planners can utilize the various lead times to deal with the risk of uncertainty. This paper proposes a novel framework for TEP under an uncertain environment, which includes investment options with various lead times. A multi-stage model is developed to reflect the different lead times in the planning method. The level of demand uncertainty is represented using a relative standard deviation. Demand uncertainty in the presented multi-stage model and its influence on the optimal decision are studied. The problem is formulated as a mixed integer linear problem to which stochastic programming is applied, and the proposed framework is illustrated from case studies on a modified Garver’s six-bus system. The case studies verify the effectiveness of the framework for TEP problems with a mathematically tractable model and demonstrates that the proposed method achieves better performance than other methods when the problems involve investment candidates with various lead times under uncertain conditions. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
On Small Signal Frequency Stability under Virtual Inertia and the Role of PLLs
Energies 2018, 11(9), 2372; https://doi.org/10.3390/en11092372 - 08 Sep 2018
Cited by 13 | Viewed by 1507
Abstract
This paper presents a methodology that aims at identifying virtual inertia (VI) gain limitations from virtual synchronous generators (VSGs) while maintaining the frequency stability considering the delay associated with the frequency measurement process. The phase-locked loop (PLL) is typically used for frequency estimation [...] Read more.
This paper presents a methodology that aims at identifying virtual inertia (VI) gain limitations from virtual synchronous generators (VSGs) while maintaining the frequency stability considering the delay associated with the frequency measurement process. The phase-locked loop (PLL) is typically used for frequency estimation that is used to calculate the rate of change of frequency (RoCoF) and it drives the VI loop. The PLL is generally accompanied by a low-pass filter that aims to suppress the impact of harmonics. This filter introduces a delay that when used with the VI control loop causes stability issues for high values of VI gain. A comparison of various PLL approaches suggests that certain variants tend to permit higher value of cut-off frequencies which can be utilized to increase the VI gain limit from VSG. This study presents a method by which the upper limit on VI gain can be quantified and related to the cut-off frequency of the PLL low pass filter that is indirectly representing the delay. It is performed using small signal frequency stability analysis on the frequency domain model of the grid with virtual inertia emulating VSG. The effective maximum VI gain from VSG is explored while satisfying the frequency measurement accuracy specification considering harmonics. The results show that the requirements of reaching a stable operation with sufficient stability margins can still be met with a faster PLL-based system and the potential increases in VI support from VSG can be quantified using the proposed method. The study has been first performed on a single machine single inverter bus (SMSIB) system and is generalized to the multi-machine and multi-inverter system. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
A Distribution Static Compensator Using a CFNN-AMF Controller for Power Quality Improvement and DC-Link Voltage Regulation
Energies 2018, 11(8), 1996; https://doi.org/10.3390/en11081996 - 01 Aug 2018
Cited by 3 | Viewed by 1117
Abstract
A distribution static compensator (DSTATCOM) is proposed in this study to improve the power quality, which includes the total harmonic distortion (THD) of the grid current and power factor (PF), of a mini grid with nonlinear and linear inductive loads. Moreover, the DC-link [...] Read more.
A distribution static compensator (DSTATCOM) is proposed in this study to improve the power quality, which includes the total harmonic distortion (THD) of the grid current and power factor (PF), of a mini grid with nonlinear and linear inductive loads. Moreover, the DC-link voltage regulation control of the DSTATCOM is essential especially under load variation conditions. Therefore, to improve the power quality and keep the DC-link voltage of the DSTATCOM constant under the variation of nonlinear and linear loads effectively, the traditional proportional-integral (PI) controller is substituted with a new online trained compensatory fuzzy neural network with an asymmetric membership function (CFNN-AMF) controller. In the proposed CFNN-AMF, the compensatory parameter to integrate pessimistic and optimistic operations of fuzzy systems is embedded in the CFNN. Furthermore, the dimensions of the Gaussian membership functions are directly extended to AMFs for the optimization of the fuzzy rules and the upgrade of learning ability of the networks. In addition, the network structure and online learning algorithm of the proposed CFNN-AMF are introduced in detail. Finally, the effectiveness and feasibility of the DSTATCOM using the proposed CFNN-AMF controller to improve the power quality and maintain the constant DC-link voltage under the change of nonlinear and linear inductive loads have been demonstrated by some experimental results. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
Assessment of the Impact of Geomagnetic Disturbances on Korean Electric Power Systems
Energies 2018, 11(7), 1920; https://doi.org/10.3390/en11071920 - 23 Jul 2018
Cited by 4 | Viewed by 1591
Abstract
Geomagnetic disturbances have the potential to impact the operation of electric power systems, and thus the assessment of their impacts is required as the first step for secure power system operations. While the effects of the disturbances have been observed primarily at higher [...] Read more.
Geomagnetic disturbances have the potential to impact the operation of electric power systems, and thus the assessment of their impacts is required as the first step for secure power system operations. While the effects of the disturbances have been observed primarily at higher latitudes, geomagnetic problems are also observed at mid and low latitude locations, in particular including neighboring countries to Korea such as China and Japan. This paper deals with the assessment of impact of geomagnetic disturbances on Korean electric power systems. For the assessment, the geoelectric fields induced by the geomagnetic disturbances are calculated using geomagnetic data measured over the past 20 years in order to quantify the strength of geomagnetic events in Korea. Then, the geomagnetic currents on the grid driven by the geoelectric fields are computed. Finally, the increased reactive power absorption in high voltage transformers is analyzed and accordingly the change of system voltage magnitudes is identified to evaluate whether the system maintains the voltage stability. The systematic study concludes that during a strong geomagnetic disturbance, the Korean electric power system satisfies the associated standards in the U.S. and maintains system stability. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
Complex Affine Arithmetic-Based Power Flow Analysis for Zonal Medium Voltage Direct Current Shipboard Power Systems in the Presence of Power Variation
Energies 2018, 11(7), 1697; https://doi.org/10.3390/en11071697 - 01 Jul 2018
Cited by 1 | Viewed by 1141
Abstract
The medium-voltage direct-current (MVDC) ship power system has been extensively investigated and discussed in recent years. This paper presents an alternating current/direct-current (AC/DC) power flow algorithm based on complex affine arithmetic for the zonal MVDC shipboard power system in the presence of power [...] Read more.
The medium-voltage direct-current (MVDC) ship power system has been extensively investigated and discussed in recent years. This paper presents an alternating current/direct-current (AC/DC) power flow algorithm based on complex affine arithmetic for the zonal MVDC shipboard power system in the presence of power variation. The power converter effect is considered, and an affine power converter model is proposed in the power flow model. An affine-analysis-based sequential method is adopted to solve AC/DC power flows. With the proposed algorithm, the bounds of bus voltages can be effectively obtained. A relative influence factor is defined to quantitatively assess the effect of power variation on voltage profile. Four cases are studied in detail to demonstrate the applicability of the proposed algorithm. The proposed algorithm is useful in network architecture design, planning, and online operations of MVDC power systems when such decisions are subject to power variation. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
Fully-distributed Load Frequency Control Strategy in an Islanded Microgrid Considering Plug-In Electric Vehicles
Energies 2018, 11(6), 1613; https://doi.org/10.3390/en11061613 - 20 Jun 2018
Cited by 11 | Viewed by 1720
Abstract
With large-scale integration of electric vehicles, this paper investigates the load frequency control problem in an islanded microgrid with plug-in electric vehicles (PEVs), which can be regarded as mobile battery energy storages to provide a valuable contribution to frequency regulation. A novel fully-distributed [...] Read more.
With large-scale integration of electric vehicles, this paper investigates the load frequency control problem in an islanded microgrid with plug-in electric vehicles (PEVs), which can be regarded as mobile battery energy storages to provide a valuable contribution to frequency regulation. A novel fully-distributed control strategy is proposed to achieve fast frequency regulation of islanded microgrids and effective coordination control of distributed energy sources. Firstly, distributed control based on an improved linear active disturbance rejection algorithm is realized through a multi-agent system, and it greatly enhances the anti-disturbance capability of the microgrid. Then, in order to guarantee the effectiveness of PEVs in frequency regulation, PEVs are controlled following the controllable power rate (CPR) calculated from the consensus-based multi-agent system. Furthermore, the system control construction in this paper is well designed to avoid the negative effects caused by system communication time delay. Finally, numerical simulations under different disturbances are carried out to demonstrate the effectiveness of the proposed control strategy in comparison with other previous control strategies. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
Analysis and Improvement of Adaptive Coefficient Third Harmonic Voltage Differential Stator Grounding Protection
Energies 2018, 11(6), 1430; https://doi.org/10.3390/en11061430 - 03 Jun 2018
Cited by 2 | Viewed by 1420
Abstract
This paper presents a novel third harmonic voltage differential stator grounding protection (THV-DSGP) method combining the adaptive coefficient and fixed coefficient. It can solve the protection sensitivity degradation problem when the insulation resistance of stator winding to ground is slowly declining. This protection [...] Read more.
This paper presents a novel third harmonic voltage differential stator grounding protection (THV-DSGP) method combining the adaptive coefficient and fixed coefficient. It can solve the protection sensitivity degradation problem when the insulation resistance of stator winding to ground is slowly declining. This protection method retains the advantages of the adaptive coefficient, which is to maintain high sensitivity in case of an instantaneous ground fault. Moreover, the fixed coefficient can remember the initial insulation state of the stator winding and prevent relay failure when the stator insulation is slowly declining. In addition, due to zero-sequence voltage disconnection (ZSVD) often leading to malfunctioning of the THV stator ground protection, the existing criterion of the ZSVD was improved according to the electrical characteristics of the generator when ZSVD happens. THV-DSGP with both adaptive coefficient and fixed coefficient was simulated in the Matlab/Simulink. The simulation results show that the proposed protection can be applied to the slow ground fault of the stator winding. Furthermore, the improved criterion of ZSVD can effectively distinguish the stator metal earth fault and the secondary loop break of the zero-sequence voltage. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
Development of Reclosing Method in a Distribution System with Distributed Generation and Battery Energy Storage System
Energies 2018, 11(6), 1407; https://doi.org/10.3390/en11061407 - 31 May 2018
Cited by 3 | Viewed by 1667
Abstract
The connection of distributed generation (DG) and a battery energy storage system (BESS) in distribution systems has recently been increasing. However, little research has been conducted on the reclosing of the distribution system when both the DG and BESS are connected. Therefore, this [...] Read more.
The connection of distributed generation (DG) and a battery energy storage system (BESS) in distribution systems has recently been increasing. However, little research has been conducted on the reclosing of the distribution system when both the DG and BESS are connected. Therefore, this paper proposes a new reclosing method for a distribution system with a DG and BESS. The proposed method also has a circuit breaker (CB) installed in the distribution line. A CB close to the DG and BESS is first reclosed after a fixed dead time and, then, the fault clearance is detected using the current flowing to the fault point. Once the fault is cleared, the reclosing of the CB at the source side is attempted after completing a synchronism check. The proposed method is modeled using an electromagnetic transient program. We perform various simulations according to the capacities of the DG and the fault clearance time, and analyze the simulation results. The simulation results show that steady-state power is supplied to the load from the DG and BESS before reclosing to prevent outage, and that the reclosing is successfully performed. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
Improved Genetic Algorithm-Based Unit Commitment Considering Uncertainty Integration Method
Energies 2018, 11(6), 1387; https://doi.org/10.3390/en11061387 - 29 May 2018
Cited by 14 | Viewed by 1304
Abstract
In light of the dissemination of renewable energy connected to the power grid, it has become necessary to consider the uncertainty in the generation of renewable energy as a unit commitment (UC) problem. A methodology for solving the UC problem is presented by [...] Read more.
In light of the dissemination of renewable energy connected to the power grid, it has become necessary to consider the uncertainty in the generation of renewable energy as a unit commitment (UC) problem. A methodology for solving the UC problem is presented by considering various uncertainties, which are assumed to have a normal distribution, by using a Monte Carlo simulation. Based on the constructed scenarios for load, wind, solar, and generator outages, a combination of scenarios is found that meets the reserve requirement to secure the power balance of the power grid. In those scenarios, the uncertainty integration method (UIM) identifies the best combination by minimizing the additional reserve requirements caused by the uncertainty of power sources. An integration process for uncertainties is formulated for stochastic unit commitment (SUC) problems and optimized by the improved genetic algorithm (IGA). The IGA is composed of five procedures and finds the optimal combination of unit status at the scheduled time, based on the determined source data. According to the number of unit systems, the IGA demonstrates better performance than the other optimization methods by applying reserve repairing and an approximation process. To account for the result of the proposed method, various UC strategies are tested with a modified 24-h UC test system and compared. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
ICT Based Performance Evaluation of Primary Frequency Control Support from Renewable Power Plants in Smart Grids
Energies 2018, 11(6), 1329; https://doi.org/10.3390/en11061329 - 23 May 2018
Cited by 3 | Viewed by 1671
Abstract
The increased penetration of Renewable Energy Generation (ReGen) plants in future power systems poses several challenges to the stability of the entire system. In future green energy rich power systems, the responsibility for providing ancillary services will be shifted from conventional power plants [...] Read more.
The increased penetration of Renewable Energy Generation (ReGen) plants in future power systems poses several challenges to the stability of the entire system. In future green energy rich power systems, the responsibility for providing ancillary services will be shifted from conventional power plants towards ReGen plants, such as wind and photovoltaic power plants. Frequency control support from the Wind Power Plants (WPPs) is one of the crucial ancillary services in order to preserve operational stability in case of grid disturbances. Among other requirements, the ability to provide fast frequency control support from ReGen plants will highly depend on the underlying communication infrastructure that allows an exchange of information between different ReGen plants and the control centers. This paper, therefore, focuses on the evaluation of the impact of communication and the related aspects to provide online frequency control support from ReGen (with special focus on WPP). The performance evaluation is based on an aggregated WPP model that is integrated into a generic power system model. This generic power system model is specifically designed to assess the ancillary services in a relatively simple yet relevant environment. Several case studies with different wind speeds at a particular wind-power penetration level and communication scenarios are considered to evaluate the performance of power system frequency response. The article provides the Transmission System Operator (TSO) and other communication engineers insights into the importance and various aspects of communication infrastructure for general service coordination between WPPs and specifically primary frequency control coordination from WPPs in future power systems. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
Residential Electricity Consumption Level Impact Factor Analysis Based on Wrapper Feature Selection and Multinomial Logistic Regression
Energies 2018, 11(5), 1180; https://doi.org/10.3390/en11051180 - 08 May 2018
Cited by 6 | Viewed by 1490
Abstract
This paper aims to identity the significant impact factors (IFs) of the residential electricity consumption level (RECL) and to better understand the influence mechanism of IFs on RECL. The analysis of influence mechanism is commonly through regression model where feature selection must first [...] Read more.
This paper aims to identity the significant impact factors (IFs) of the residential electricity consumption level (RECL) and to better understand the influence mechanism of IFs on RECL. The analysis of influence mechanism is commonly through regression model where feature selection must first be performed to pick out non-redundant IFs that is highly correlated with RECL. In contrast to the existing studies, this study recognizes the problem that majority feature selection methods (e.g., step regression) are limited to the identification of linear relationships and proposes a novel wrapper feature selection (WFS) method to address this issue. The WFS is based on genetic algorithm (GA) and multinomial logistic regression (MLR). GA is a searching algorithm used to generate different feature subsets (FSs) that consist of several IFs. MLR is a modeling algorithm used to score these FSs. Further, maximal information coefficient (MIC) is utilized to verify the validity of WFS for selecting IFs. Finally, MLR based explanatory model is established to excavate the relationship between selected IFs and RECL. The results of Ireland dataset based case study show that WFS can identify the significant and non-redundant IFs that are linearly or nonlinearly related to RECL. The details about how selected IFs affect RECL are also provided via the explanatory model. Such research can provide useful guidance for a wide range of stakeholders including local governments, electric power companies, and individual households. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
Optimal Design and Real Time Implementation of Autonomous Microgrid Including Active Load
Energies 2018, 11(5), 1109; https://doi.org/10.3390/en11051109 - 01 May 2018
Cited by 7 | Viewed by 1705
Abstract
Controller gains and power-sharing parameters are the main parameters affect the dynamic performance of the microgrid. Considering an active load to the autonomous microgrid, the stability problem will be more involved. In this paper, the active load effect on microgrid dynamic stability is [...] Read more.
Controller gains and power-sharing parameters are the main parameters affect the dynamic performance of the microgrid. Considering an active load to the autonomous microgrid, the stability problem will be more involved. In this paper, the active load effect on microgrid dynamic stability is explored. An autonomous microgrid including three inverter-based distributed generations (DGs) with an active load is modeled and the associated controllers are designed. Controller gains of the inverters and active load as well as Phase Locked Loop (PLL) parameters are optimally tuned to guarantee overall system stability. A weighted objective function is proposed to minimize the error in both measured active power and DC voltage based on time-domain simulations. Different AC and DC disturbances are applied to verify and assess the effectiveness of the proposed control strategy. The results demonstrate the potential of the proposed controller to enhance the microgrid stability and to provide efficient damping characteristics. Additionally, the proposed controller is compared with the literature to demonstrate its superiority. Finally, the microgrid considered has been established and implemented on real time digital simulator (RTDS). The experimental results validate the simulation results and approve the effectiveness of the proposed controllers to enrich the stability of the considered microgrid. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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Open AccessArticle
Wide-Area Measurement—Based Model-Free Approach for Online Power System Transient Stability Assessment
Energies 2018, 11(4), 958; https://doi.org/10.3390/en11040958 - 17 Apr 2018
Cited by 12 | Viewed by 1626
Abstract
Online assessment of transient stability of power systems is critical for avoiding blackout. The increasing installation of phasor measurement units in power systems and the advancement of the wide-area measurement systems make it possible to develop methods for online assessment of power systems [...] Read more.
Online assessment of transient stability of power systems is critical for avoiding blackout. The increasing installation of phasor measurement units in power systems and the advancement of the wide-area measurement systems make it possible to develop methods for online assessment of power systems by using a large amount of real-time synchronous data. In this paper, we propose an approach based on the largest Lyapunov exponent (LLE) for online transient rotor angle stability assessment, using only wide-area measurement systems data. Through establishing a mathematical model that accounts for the LLE value and the rotor speed, as well as analyzing the post-fault phase-plane trajectory, we present a fast stability criterion to determine whether transient instability occurs. The proposed approach is model-free and does not need long-time LLE data to identify the final sign of the LLE. Furthermore, to reduce computational cost and realize online assessment for large-scale power systems, the critical generator pair (CGP) is recognized as the observation for the rotor angle stability assessment, and an effective algorithm for identifying the CGP is presented. Several case studies on the IEEE-39 bus test system and East China power grid are reported to demonstrate the accuracy and effectiveness of the proposed approach. Full article
(This article belongs to the Special Issue Electric Power Systems Research 2018)
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