Special Issue "HVDC/FACTS for Grid Services in Electric Power Systems"

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 (1 September 2019).

Special Issue Editors

Prof. Dr. Jose Maria Maza Ortega
Website
Guest Editor
Department of electrical engineering, University of Seville, 4 San Fernando Str. Sevilla 41004, Spain
Interests: management of electric energy; efficient management of electric energy; electrical machines; electric energy systems; quality and efficiency of power supply; AC/DC devices and systems
Prof. Dr. Antonio Gomez-Exposito
Website
Guest Editor
Department of Electrical Engineering, University of Seville, 4 San Fernando Str. Sevilla 41004, Spain
Interests: circuit theory; electrical power systems; transient and dynamic analysis of electrical systems; operation and control of electrical systems; electric power systems II; transient and dynamic analysis of electrical systems; AC/DC devices and systems; numerical methods for electrical systems; operation and control of electrical systems

Special Issue Information

Dear Colleagues,

Electric power systems are headed for a true changing of the guard due to the urgent need for decarbonized and sustainable energy delivery. Fortunately, the development of new technologies is driving the transition of power systems towards a carbon-free paradigm, while at the same time maintaining current standards of quality, efficiency and resiliency. The introduction of HVDC and FACTS in the 20th century, taking advantage of dramatic improvements in power electronics and control, gave rise to unprecedented levels of flexibility and speed of response in comparison with traditional electromechanical devices. This flexibility is nowadays more required than ever in order to solve a puzzle with pieces that do not always fit perfectly.

This Special Issue aims to address the role that FACTS and HVDC systems can play in helping electric power systems face the challenges of the near future. The contributions should preferably focus on the grid services that these technologies may bring, rather than on advances in individual devices. The topics of interest include, but are not limited to:

  • HVDC/FACTS providing services for transmission systems in combination with renewable plants and/or storage systems: frequency control, var/voltage regulation, backup reserve, energy imbalance, inertia provision, congestion release, load following, black-start capability, remote automatic generation control, network loss reduction, emergency control action, etc.
  • MVDC/D-FACTS providing services for distribution systems in combination with distributed generation and storage: voltage control, reactive power support, supply restoration, power quality maintenance, congestion management, balancing and reconfiguration, integration of renewable energies, etc.
  • Application of innovative devices or concepts based on HVDC/FACTS technologies for providing grid services: advanced secondary substations involving custom power devices, hybrid AC/DC transmission and distribution systems, advanced charging stations for electric vehicles, etc.
  • Advanced control systems for HVDC/FACTS providing grid services: centralized and distributed approaches, coordinated controllers with minimal communication infrastructure, robust controllers, etc.

Prof. Dr. Jose Maria Maza Ortega
Prof. Dr. Antonio Gomez-Exposito
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

  • HVDC
  • FACTS
  • Ancillary services
  • Decarbonized power systems

Published Papers (13 papers)

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Research

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Open AccessFeature PaperArticle
Ride-Through Control Method for the Continuous Commutation Failures of HVDC Systems Based on DC Emergency Power Control
Energies 2019, 12(21), 4183; https://doi.org/10.3390/en12214183 - 02 Nov 2019
Cited by 1
Abstract
Continuous commutation failures (CFs) are serious malfunctions in line-commutated converter high-voltage direct current (HVDC) systems that cause the continuous and rapid sag of transmitted power and may threaten the stability of AC systems. The conventional emergency control strategies of AC systems exhibit difficulty [...] Read more.
Continuous commutation failures (CFs) are serious malfunctions in line-commutated converter high-voltage direct current (HVDC) systems that cause the continuous and rapid sag of transmitted power and may threaten the stability of AC systems. The conventional emergency control strategies of AC systems exhibit difficulty in responding quickly and accurately. After suffering from continuous CFs, the forced blocking of direct current (DC) converter to prevent AC system instability might also cause other adverse effects. This study proposes a ride-through control method to improve the endurance capability of AC systems against continuous CFs. An active power output model of inverter station under continuous CFs is built, while considering the process and mechanism of CFs. The impact of continuous DC power sag on the stability of sending-end system is analyzed through a four-area AC/DC equivalent model. A rolling calculation model for the power angle and acceleration area variations of the sending-end system during continuous CFs is established on the basis of model predictive control theory. A calculation method for the emergency power control reference is obtained by using the aforementioned models. Lastly, a ride-through control method for continuous CFs is developed by utilizing the emergency control of adjacent HVDC link. Simulation results show that the proposed control method can improve the endurance capability of an AC system to continuous CFs and reduce blocking risk in an HVDC link. Full article
(This article belongs to the Special Issue HVDC/FACTS for Grid Services in Electric Power Systems)
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Open AccessArticle
A Neural Network-Based Model Reference Control Architecture for Oscillation Damping in Interconnected Power System
Energies 2019, 12(19), 3653; https://doi.org/10.3390/en12193653 - 24 Sep 2019
Abstract
In this paper, a model reference controller (MRC) based on a neural network (NN) is proposed for damping oscillations in electric power systems. Variation in reactive load, internal or external perturbation/faults, and asynchronization of the connected machine cause oscillations in power systems. If [...] Read more.
In this paper, a model reference controller (MRC) based on a neural network (NN) is proposed for damping oscillations in electric power systems. Variation in reactive load, internal or external perturbation/faults, and asynchronization of the connected machine cause oscillations in power systems. If the oscillation is not damped properly, it will lead to a complete collapse of the power system. An MRC base unified power flow controller (UPFC) is proposed to mitigate the oscillations in 2-area, 4-machine interconnected power systems. The MRC controller is using the NN for training, as well as for plant identification. The proposed NN-based MRC controller is capable of damping power oscillations; hence, the system acquires a stable condition. The response of the proposed MRC is compared with the traditionally used proportional integral (PI) controller to validate its performance. The key performance indicator integral square error (ISE) and integral absolute error (IAE) of both controllers is calculated for single phase, two phase, and three phase faults. MATLAB/Simulink is used to implement and simulate the 2-area, 4-machine power system. Full article
(This article belongs to the Special Issue HVDC/FACTS for Grid Services in Electric Power Systems)
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Open AccessArticle
Coordinated Control in VSC-HVDC Multi-Terminal Systems to Improve Transient Stability: The Impact of Communication Latency
Energies 2019, 12(19), 3638; https://doi.org/10.3390/en12193638 - 24 Sep 2019
Cited by 1
Abstract
Power transmission is the main purpose of high voltage direct current systems based on voltage source converters (VSC-HVDC). Nevertheless, this type of system can also help to improve transient stability by implementing suitable supplementary controllers. Previous work proposed active- (P) and reactive-power (Q) [...] Read more.
Power transmission is the main purpose of high voltage direct current systems based on voltage source converters (VSC-HVDC). Nevertheless, this type of system can also help to improve transient stability by implementing suitable supplementary controllers. Previous work proposed active- (P) and reactive-power (Q) control strategies in VSC-HVDC multi-terminal systems (VSC-MTDC, for short) to improve transient stability, producing significant improvements. In those strategies, each VSC station of the MTDC system compares its frequency measurement with the average of the frequencies measured by all converter stations of the MTDC system (weighted-average frequency, WAF) in order to modulate its own P and Q injections. Hence, a communication system is required. This paper presents a detailed analysis of the impact of communication latency on the performance of those control strategies. The communication delays have been modelled using a Padé’s approximation and their impact on the performance of the control strategies have been assessed by means of time-domain simulation in PSS/E. The effect of the control strategies on transient stability has been quantified with the critical clearing time (CCT) of a set of faults. Results show that the control strategies analysed present good results for realistic values of communication delays. Full article
(This article belongs to the Special Issue HVDC/FACTS for Grid Services in Electric Power Systems)
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Open AccessArticle
Modeling and Control of a Novel Hybrid Power Quality Compensation System for 25-kV Electrified Railway
Energies 2019, 12(17), 3303; https://doi.org/10.3390/en12173303 - 27 Aug 2019
Cited by 3
Abstract
The severe power quality problems aroused by the single-phase 25-kV traction power supply system (TPSS), especially for the voltage unbalance (VU) and high-frequency harmonic resonance, have attracted increasing attention nowadays. In this paper, a novel hybrid power quality compensation system, including a power [...] Read more.
The severe power quality problems aroused by the single-phase 25-kV traction power supply system (TPSS), especially for the voltage unbalance (VU) and high-frequency harmonic resonance, have attracted increasing attention nowadays. In this paper, a novel hybrid power quality compensation system, including a power flow controller (PFC) and thyristor-controlled L and C-type filter (TCL-CTF), is proposed. The PFC can be used for VU compensation, and the TCL-CTF can be designed to filter out harmonics as well as compensate reactive power. Furthermore, an optimized compensation strategy is proposed, and the power quality of the TPSS can meet the requirements of the technology standard. Compared with the conventional scheme, the compensation capacity of the PFC can be reduced by 12%, as well as the cost. Finally, the effectiveness of the proposed system is verified by the simulation and experimental results. Full article
(This article belongs to the Special Issue HVDC/FACTS for Grid Services in Electric Power Systems)
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Open AccessArticle
Power Quality Services Provided by Virtually Synchronous FACTS
Energies 2019, 12(17), 3292; https://doi.org/10.3390/en12173292 - 27 Aug 2019
Cited by 1
Abstract
The variable and unpredictable behavior of renewable energies impacts the performance of power systems negatively, threatening their stability and hindering their efficient operation. Flexible ac transmission systems (FACTS) devices are able to emulate the connection of parallel and series impedances in the transmission [...] Read more.
The variable and unpredictable behavior of renewable energies impacts the performance of power systems negatively, threatening their stability and hindering their efficient operation. Flexible ac transmission systems (FACTS) devices are able to emulate the connection of parallel and series impedances in the transmission system, which improves the regulation of power systems with a high share of renewables, avoiding congestions, enhancing their response in front of contingencies and, in summary, increasing their utilization and reliability. Proper control of voltage and current under distorted and unbalanced transient grid conditions is one of the most critical issues in the control of FACTS devices to emulate such apparent impedances. This paper describes how the synchronous power controller (SPC) can be used to implement virtually synchronous FACTS. It presents the SPC functionalities, emphasizing in particular the importance of virtual admittance emulation by FACTS devices in order to control transient unbalanced currents during faults and attenuate harmonics. Finally, the results demonstrate the effectiveness of SPC-based FACTS devices in improving power quality of electrical networks. This is a result of their contribution to voltage balancing at point of connection during asymmetrical faults and the improvement of grid voltage quality by controlling harmonics flow. Full article
(This article belongs to the Special Issue HVDC/FACTS for Grid Services in Electric Power Systems)
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Open AccessArticle
Analysis and Mitigation of Subsynchronous Resonance in a Korean Power Network with the First TCSC Installation
Energies 2019, 12(15), 2847; https://doi.org/10.3390/en12152847 - 24 Jul 2019
Abstract
This paper presents a detailed analysis results of the effect of a thyristor-controlled series capacitor (TCSC) on subsynchronous resonance (SSR), which was first applied to a Korean power system. First, the TCSC parameters were calculated, the structure of TCSC with synchronous voltage reversal [...] Read more.
This paper presents a detailed analysis results of the effect of a thyristor-controlled series capacitor (TCSC) on subsynchronous resonance (SSR), which was first applied to a Korean power system. First, the TCSC parameters were calculated, the structure of TCSC with synchronous voltage reversal (SVR) controller was presented, and the torsional characteristics of Hanul nuclear power generator rotor were studied to investigate the natural frequency and mode shape. The test signal method was used to determine the electrical damping in the frequency range of SSR operation through an electromagnetic transient analysis program in various system configurations. The SSR phenomenon was analyzed by comparing the electrical and mechanical damping of a conventional fixed series capacitor (FSC), and the case of a TCSC installed, and the effectiveness of the TCSC without any risk of SSR was demonstrated. As a result, when installing FSC, SSR occurred under sensitive operating conditions, but SSR was prevented in the case of TCSC compensation with SVR. The results obtained in this study can be effectively applied to the installation of TCSC in real power systems. Full article
(This article belongs to the Special Issue HVDC/FACTS for Grid Services in Electric Power Systems)
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Open AccessArticle
A Hybrid DC Circuit Breaker with Fault-Current-Limiting Capability for VSC-HVDC Transmission System
Energies 2019, 12(12), 2388; https://doi.org/10.3390/en12122388 - 21 Jun 2019
Cited by 5
Abstract
The direct current circuit breakers are considered a promising option to protect the transmission line against commonly appearing line-to-ground fault. However, the challenges of losses in the nonoperational stage, escalation of response against fault current, and large fault current handling capability remain the [...] Read more.
The direct current circuit breakers are considered a promising option to protect the transmission line against commonly appearing line-to-ground fault. However, the challenges of losses in the nonoperational stage, escalation of response against fault current, and large fault current handling capability remain the debatable issues for direct current circuit breakers. This paper introduces a novel topology of the hybrid circuit breaker with fault-current-limiting characteristics, which contains three branches: the main branch, fault-current-limiting branch, and energy absorption branch. The main branch includes a mechanical switch, breaker impedance, and bidirectional power electronics switches. In the fault-current-limiting branch, a fault-current-limiting circuit is introduced which contains n numbers of bidirectional switches and current-limiting inductors, which are connected in series to make the design modular in nature. During the normal working stage, the current flows through the main branch of the breaker. Once a fault in the system is confirmed, the fault current is transferred to the fault-current-limiting branch. At this stage, the intensity of the fault current is reduced significantly using the fault-current-limiting circuit, and finally, the residual current is shifted to the energy absorption branch. The working principle, design considerations, and parametric analysis concerning the design of hybrid circuit breakers are incorporated in this paper. The performance of the proposed breaker is evaluated using a three-terminal voltage-source converter-based high-voltage direct current transmission network; for this purpose, a PSCAD/EMTDC simulation tool is used. The performance of the proposed breaker is also compared with other topologies. The comparative analysis shows that the proposed breaker is a good alternative considering high fault current interruption requirements, response time against fault current, and power losses. Full article
(This article belongs to the Special Issue HVDC/FACTS for Grid Services in Electric Power Systems)
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Open AccessArticle
An Operation Strategy of the Hybrid Multi-Terminal HVDC for Contingency
Energies 2019, 12(11), 2042; https://doi.org/10.3390/en12112042 - 28 May 2019
Cited by 2
Abstract
The application of the direct current (DC) transmission is increasing through the interconnection between grids or the renewable energy resource integration. Various types of DC transmission topology are researched, and the hybrid multi-terminal high voltage DC (HVDC), called the “MTDC”, is one of [...] Read more.
The application of the direct current (DC) transmission is increasing through the interconnection between grids or the renewable energy resource integration. Various types of DC transmission topology are researched, and the hybrid multi-terminal high voltage DC (HVDC), called the “MTDC”, is one of the research subjects. The hybrid multi-terminal HVDC is the MTDC system that is composed with the Line Commutated Converter (LCC) and Voltage Source Converter (VSC). Most hybrid MTDC research has been focused on the connection of the renewable energy generation sources, especially offshore wind farms. However, the DC grid built with a hybrid MTDC was recently proposed due to the development of the converter technology. Therefore, the DC grid is expected to be able to substitute some parts of the transmission grid instead of the alternating current (AC) system, and the operation strategies of the DC grid are still being researched. The DC grid has the advantage of being able to control the power flow, which can even improve the stability of the connected AC system. The dynamic model is required to analyze the improvement of the AC system by the operation strategy of the hybrid MTDC, however, there is no generic model for the system. In this paper, an operation strategy of the hybrid MTDC is proposed to improve the stability of the AC power system by increasing the utilization of parallel AC transmission lines under the contingency condition. Furthermore, studies on the modeling method for a hybrid MTDC analysis were performed. The proposed modeling method and operation strategy were verified in simulations for which a modified IEEE 39 bus test system was used. The improvement of transient stability by the proposed hybrid MTDC system was shown in the simulation results. Full article
(This article belongs to the Special Issue HVDC/FACTS for Grid Services in Electric Power Systems)
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Open AccessArticle
Reactive Power Compensation and Imbalance Suppression by Star-Connected Buck-Type D-CAP
Energies 2019, 12(10), 1914; https://doi.org/10.3390/en12101914 - 18 May 2019
Cited by 3
Abstract
Reactive power and negative-sequence current generated by inductive unbalanced load will not only increase line loss, but also cause the malfunction of relay protection devices triggered by a negative-sequence component in the power grid, which threatens the safe operation of the power system, [...] Read more.
Reactive power and negative-sequence current generated by inductive unbalanced load will not only increase line loss, but also cause the malfunction of relay protection devices triggered by a negative-sequence component in the power grid, which threatens the safe operation of the power system, so it is particularly important to compensate reactive power and suppress load imbalance. In this paper, reactive power compensation and imbalance suppression by a three-phase star-connected Buck-type dynamic capacitor (D-CAP) under an inductive unbalanced load are studied. Firstly, the relationship between power factor correction and imbalance suppression in a three-phase three-wire system is discussed, and the principle of D-CAP suppressing load imbalance is analyzed. Next, its compensation ability for negative-sequence currents is determined, which contains theoretical and actual compensation ability. Then an improved control strategy to compensate reactive power and suppress imbalance is proposed. If the load is slightly unbalanced, the D-CAP can completely compensate the reactive power and negative-sequence currents. If the load is heavily unbalanced, the D-CAP can only compensate the positive-sequence reactive power and a part of the negative-sequence currents due to the limit of compensation ability. Finally, a 33 kVar/220 V D-CAP prototype is built and experimental results verify the theoretical analysis and control strategy. Full article
(This article belongs to the Special Issue HVDC/FACTS for Grid Services in Electric Power Systems)
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Open AccessArticle
Active and Reactive Power Compensation Control Strategy for VSC-HVDC Systems under Unbalanced Grid Conditions
Energies 2018, 11(11), 3140; https://doi.org/10.3390/en11113140 - 13 Nov 2018
Cited by 3
Abstract
This paper presents a power compensation strategy to suppress the double frequency power ripples of Voltage source converter high-voltage direct current (VSC-HVDC) systems under unbalanced grid voltage conditions. The mathematical control equations of the double frequency ripple power of VSC under unbalanced operating [...] Read more.
This paper presents a power compensation strategy to suppress the double frequency power ripples of Voltage source converter high-voltage direct current (VSC-HVDC) systems under unbalanced grid voltage conditions. The mathematical control equations of the double frequency ripple power of VSC under unbalanced operating conditions are firstly derived and established, where the dynamic behaviors of the double frequency ripples in active and reactive power are regarded as being driven by current-relevant components and voltage-relevant components, respectively. Based on the equations, a power compensation control strategy of VSC-HVDC is proposed via the passivity-based control with disturbance observer to suppress both the current-relevant and voltage-relevant components in the power ripples. With this control strategy, the double frequency ripples in active and reactive power are suppressed simultaneously and system performance is significantly enhanced with the implementation of the disturbance observer in the passivity-based control. Theoretical stability analysis and simulation cases show the effectiveness and superiority of the proposed strategy. Full article
(This article belongs to the Special Issue HVDC/FACTS for Grid Services in Electric Power Systems)
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Review

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Open AccessReview
Ancillary Services in Hybrid AC/DC Low Voltage Distribution Networks
Energies 2019, 12(19), 3591; https://doi.org/10.3390/en12193591 - 20 Sep 2019
Cited by 2
Abstract
In the last decade, distribution systems are experiencing a drastic transformation with the advent of new technologies. In fact, distribution networks are no longer passive systems, considering the current integration rates of new agents such as distributed generation, electrical vehicles and energy storage, [...] Read more.
In the last decade, distribution systems are experiencing a drastic transformation with the advent of new technologies. In fact, distribution networks are no longer passive systems, considering the current integration rates of new agents such as distributed generation, electrical vehicles and energy storage, which are greatly influencing the way these systems are operated. In addition, the intrinsic DC nature of these components, interfaced to the AC system through power electronics converters, is unlocking the possibility for new distribution topologies based on AC/DC networks. This paper analyzes the evolution of AC distribution systems, the advantages of AC/DC hybrid arrangements and the active role that the new distributed agents may play in the upcoming decarbonized paradigm by providing different ancillary services. Full article
(This article belongs to the Special Issue HVDC/FACTS for Grid Services in Electric Power Systems)
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Open AccessFeature PaperReview
An Overview of Ancillary Services and HVDC Systems in European Context
Energies 2019, 12(18), 3481; https://doi.org/10.3390/en12183481 - 09 Sep 2019
Cited by 2
Abstract
Liberalization of electricity markets has brought focus on the optimal use of generation and transmission infrastructure. In such a scenario, where the power transmission systems are being operated closer to their critical limits, Ancillary Services (AS) play an important role in ensuring secure [...] Read more.
Liberalization of electricity markets has brought focus on the optimal use of generation and transmission infrastructure. In such a scenario, where the power transmission systems are being operated closer to their critical limits, Ancillary Services (AS) play an important role in ensuring secure and cost-effective operation of power systems. Emerging converter-based HVDC technologies and integration of renewable energy sources (RES) have changed the power system dynamics which are based on classical power plant operation and synchronous generator dynamics. Transmission system interconnections between different countries and integrated energy markets in Europe have led to a reduction in the use of energy from non-renewable fossil-based sources. This review paper gives an insight into ancillary services definitions and market practices for procurement and activation of these ancillary services in different control areas within the European Network of Transmission System Operators for Electricity (ENTSO-E). The focus lies particularly on ancillary services from HVDC systems. It is foreseen that DC elements will play an important role in the control and management of the future power system and in particular through ancillary services provision. Keeping this in view, the capability of HVDC systems to provide ancillary services is presented. Full article
(This article belongs to the Special Issue HVDC/FACTS for Grid Services in Electric Power Systems)
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Open AccessReview
FACTS Providing Grid Services: Applications and Testing
Energies 2019, 12(13), 2554; https://doi.org/10.3390/en12132554 - 03 Jul 2019
Cited by 8
Abstract
The role of flexible alternating current transmission systems (FACTSs) in the provision of grid services is becoming increasingly important, due to the massive integration of intermittent renewable energy sources, energy storage systems, and the decommissioning of thermal plants. A comprehensive literature review of [...] Read more.
The role of flexible alternating current transmission systems (FACTSs) in the provision of grid services is becoming increasingly important, due to the massive integration of intermittent renewable energy sources, energy storage systems, and the decommissioning of thermal plants. A comprehensive literature review of grid services offered by FACTS is performed, focusing on the different grid services that they can provide, such as power flow control, reactive power control, voltage control, power quality improvement, harmonic mitigation, improvement of transient stability, and damping of inter-area and intra-area oscillations. These grid services need to be realistically and economically validated in suitable testing environments. A review of relevant standards, guides, and the literature is performed, which covers the entire range from functional specification and factory testing up to the field testing of FACTS. Advanced industry practices, such as controller hardware in the loop (CHIL) testing of FACTS controllers by the manufacturer, and recent trends, such as CHIL testing of replica controllers by the owner, are underlined. Limitations of conventional testing and CHIL testing are explained and the use of power hardware in the loop (PHIL) simulation for FACTS testing is discussed. CHIL and scaled-down PHIL tests on a transmission static synchronous compensator (STATCOM) are performed and a comparison of the results is presented. Full article
(This article belongs to the Special Issue HVDC/FACTS for Grid Services in Electric Power Systems)
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