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A constant worldwide growing load stress over a power system compelled the practice of a reactive power injection to ensure an efficient power network. For this purpose, multiple technologies exist in the knowledge market out of which this paper emphasizes the usage of the flexible alternating current transmission system (FACTS) and presents a comparative study of the static var compensator (SVC) with the static synchronous compensator (STATCOM), inducted in a real electric substation. The aim is to improve the power factor (PF) and power quality and to encounter reliably extreme conditions. A 220 kV electric substation was opted for the analysis, and both the static and dynamic conditions were observed with the help of a power system analysis tool termed PowerFactory-DIgSILENT. Multiple aspects were investigated via software simulations to assess the performance of the aforementioned FACTS devices, such as the voltage profile evaluation via the load flow analysis method (LFA), the harmonic response via the power quality and harmonic analysis tool, and the short-circuit response via the RMS simulation tool. The outcomes were verified and compared with permissible values included in the universal standards, such as IEC and IEEE. The superiority of the STATCOM over the SVC was proven in light of the simulative results. [ABSTRACT FROM AUTHOR]

This study presents a novel interfacing setup for testing and validating wide‐area monitoring and control (WAMC) techniques used in smart grids. The main purpose of this study is to provide a realistic approach for conducting WAMC studies. In here, a wide‐area controller (WAC) for a flexible AC transmission system (FACTS) device is implemented. The measurements for the WAC are collected using phasor measurements units (PMUs). Three main segments are being interfaced in this study. First, the real‐power grid, the local area controller of the actual FACTS device, and the PMUs are simulated using real‐time digital simulator. This simulation represents the central simulation and is interfaced with the WAC, which is realised using a MATLAB‐based program. This interface represents a novel software‐in‐the‐loop (SIL) scheme. On the other hand, an actual FACTS device is designed and interfaced to the central simulation via hardware‐in‐the‐loop (HIL) scheme. This SIL and HIL combination makes the experimental testbed more realistic and closer to the industrial standard. Various tests are conducted to examine the performance of the developed testbed. [ABSTRACT FROM AUTHOR]

Static synchronous compensator (STATCOM), a shunt type flexible AC transmission system device, is used to control the voltage at different locations within a power system by absorbing/injecting reactive power. The dynamic control action associated with the operation of STATCOM in both capacitive and inductive modes is the reason for varying system condition and failure of different relaying schemes. Directional relaying is affected by the reactive current contributed by STATCOM in wide range of inductive to capacitive mode of operation. Further, single pole tripping (SPT) condition during STATCOM operation leads to mal‐function of the directional element due to phase change in sequence components of voltage and current. In this study, directional relaying is addressed for different types of faults in the presence of STATCOM connected at different locations during single phase auto reclosing period. Proposed directional relaying technique is based on the phase angle between positive sequence fault and pre‐fault apparent powers. Performance of the proposed scheme has been investigated for different types of faults for single and double circuit lines during SPT using simulated data of different power networks using PSCAD/EMTDC software. A comparative study is also carried out to verify the performance of the proposed scheme for different STATCOM operating conditions. [ABSTRACT FROM AUTHOR]

This study investigates the impact of different flexible AC transmission system (FACTS) devices on critical power quality (PQ) phenomena including voltage sags, harmonics and unbalance from the perspective of both mitigation effect and potential negative impact. The FACTS devices, including static VAR compensator, static compensator (STATCOM) and dynamic voltage restorers, are modelled in commercially available software PowerFactory/DIgSILENT to study their impacts on the critical PQ phenomena. Two control strategies, voltage regulation and reactive power compensation, are considered for STATCOM. For DVR, a PI‐controller is developed for the purpose of voltage sag mitigation. The merit of the proposed controller is presented by the dynamic response of during fault voltage and the capability of post‐fault voltage recovery. The study is carried out on a large‐scale generic distribution network. The impact of various devices on PQ phenomena is assessed using appropriate evaluation methodologies, and the results obtained with and without mitigation are presented and compared using heatmaps. [ABSTRACT FROM AUTHOR]

In order to increase the power transfer and providing the optimum utilisation of the power system capability, application of flexible alternating current transmission system (FACTS) devices technology, such as static synchronous compensator (STATCOM), has been attracted, in recent years. However, the STATCOM changes the voltage and current of the power system that disturb the operation of the impedance‐based synchronous generator loss of excitation (LOE) protection. Then, this study proposes a new flux‐based LOE protection method, in the presence of STATCOM, that is based on the local variation of the flux linkage of the generator available at the location of relay. The mentioned relay is independent of other generator protection relays without any coordination. In order to show the satisfying operation of the proposed method, some simulations have been carried out in the Matlab/Simulink software. A single‐machine infinite bus and a three‐machine infinite bus systems have been used in simulations. The results show that the presence of STATCOM has no important effect on the performance of proposed relay opposite to a negative offset relay with two protective zones (the widely used impedance method) which is affected by STATCOM operation. [ABSTRACT FROM AUTHOR]

Voltage-sourced converter (VSC)-based static synchronous compensators (STATCOMs) are used for voltage regulation in transmission and distribution systems. Unlike PWM-controlled STATCOMs, angle-controlled STATCOMs are switched at line frequency to limit the system losses. In recent years, angle-controlled STATCOMs have been deployed by utilities for the purpose of transmission system voltage regulation, voltage stability improvement, and increasing operational functionality. Despite the superior feature on voltage waveform quality and efficiency, the practical angle-controlled STATCOMs suffer from the over-current (and trips) and possible saturation of the interfacing transformers caused by negative sequence current during unbalanced conditions and faults in the utility. This paper specifically proposes a control structure to improve the angle-controlled STATCOMs performance under unbalanced conditions and faults. The main improvement is a substantial decrease in the negative sequence current and dc-link voltage oscillations under power system faults by the proposed control. This eliminates the need to redesign the STACOM power components to operate under fault current and dc-link voltage oscillations. The proposed control structure is designed based on adding appropriate oscillations to the conventional angle-controller output that is the control angle by which the VSC voltage vector leads/lags the line voltage vector. Since this control structure uses two angles for controlling the VSC output voltage, it is called dual angle control (DAC). PSCAD/EMTDC and experimental results verify the validity of the proposed control structure under unbalanced system conditions and faults. The experiments were conducted on a transient network analyzer, a unique hardware-based flexible ac transmission system simulator which was designed to study system faults and transients for a 2 × 100 MVA STATCOM field installation. [ABSTRACT FROM AUTHOR]

Hydro‐Québec's electrical transmission system is an extensive, international grid located in Québec, Canada with extensions into the northeastern United States of America. For large power systems such as this, one of the major issues is to maintain the steady‐state performance of the network. From this point of view, flexible AC transmission system (FACTS) devices could be effective tools to improve power system security by reducing the power flow on overloaded lines, which in turn would result in an increased loadability of the power system, reduced transmission line losses, improved stability and security and, ultimately, a more energy‐efficient transmission system. Therefore in this study, the authors will present the effects of different types of FACTS devices on the performance of Hydro‐Québec's power system. The optimal locations and rating of these FACTS controllers will be determined with a view to improving network security using an optimisation algorithm based on a genetic algorithm. The effects of six different FACTS devices including static VAR compensator (SVC), thyristor‐controlled series capacitor (TCSC), thyristor‐controlled voltage regulator (TCVR), thyristor‐controlled phase‐shifting transformer (TCPST), unified power flow controller (UPFC) and static synchronous compensator (STATCOM) with energy storage are compared. Using the presented results, the effects of different types of FACTS devices on the Hydro‐Québec network will be analysed and compared with those of a STATCOM equipped with energy storage from the viewpoints of static loadability and losses. [ABSTRACT FROM AUTHOR]

This study presents a secondary voltage control based on an optimisation algorithm to locate the control buses and regulate the voltage. Control buses are the buses where compensators will be installed on these buses to regulate voltage and avoid voltage violations. Firstly, partitioning algorithm using fuzzy C‐means has been implemented on the power network. Partitioning techniques split the power system into regions to avoid the propagation of disturbances between regions by using local controllers. Then, a number of buses are labelled as control buses displaying the critical point for voltage control in each region. The control algorithm is a decentralised controller which tries to eliminate voltage violations in power system resulting from load variations and disturbances. The decentralised controllers are implemented using flexible AC transmission system (FACTS) devices such as static synchronous compensator (STATCOM). The methodology is applied to the IEEE 118‐bus network. The results show the performance and ability of the partitioning algorithm and bus control selection to regulate the voltage and avoid propagation of disturbances between regions. [ABSTRACT FROM AUTHOR]

This paper presents an approach to optimally select and allocate flexible ac transmission (FACTS) devices in a distribution network in order to minimize the number of voltage sags at network buses. The method proposed is based on the optimization of a preselected objective function using simple and niching genetic algorithms (GA). The objective of the optimization is to achieve the improvement in overall system sag performance of the network. Using proposed GA-based optimization, the location, the type and the rating of six (in total) FACTS devices are optimized simultaneously. Three types of FACTS devices are implemented in this study, namely, static var compensator, static compensator, and dynamic voltage restorer. The performance of the proposed algorithm is tested and illustrated on 295-bus generic distribution system. [ABSTRACT FROM PUBLISHER]

Flexible ac transmission system (FACTS) devices or their subderivative custom power devices are efficient and often used and recommended power-electronics-based devices for mitigation of voltage sags in electrical power system. With FACTS devices installed, the overall system (and individual bus) sag performance could significantly change depending on the type of the device used. In order to assess this change in sag performance in realistic large power systems, the classical (essentially static) fault calculation procedure should be amended to incorporate the effects of these devices on bus voltages. This paper presents a new approach of quasistatic sag analysis using a system impedance (Z bus ) matrix that incorporates FACTS devices. Three types of FACTS devices which are most often used in practical applications are considered in this study: static compensator, static var compensator, and the dynamic voltage restorer. The case studies based on the 295-bus generic distribution system are used to illustrate the modeling method and the effectiveness of these devices in sag mitigation. [ABSTRACT FROM PUBLISHER]

STATCOM is a FACTS controller that is used in power systems to regulate the line voltage, enhance the power transmission capacity and extend the transient stability margin. STATCOM is conventionally realized by a voltage-source converter; however, being a current injection device, its performance can be improved when realized by a current-source converter (CSC) that can generate a controllable current directly at its output terminals. In this paper, a STATCOM based on the current-source converter topology is proposed. The nonlinear model of the current-source converter, which is the source of the difficulties in the controller design, has been modified to a linear model through a novel modeling technique. The proposed modeling technique is not based on the linearization of a set of nonlinear equations around an operating point. Instead, the power balance equation and a nonlinear input transformation are used to derive a linear model independent of the operating point. This model acts as the basis for the design of a decoupled state-feedback controller. The proposed STATCOM has been simulated using the PSCAD/EMTDC package. The simulation results show that a CSC-based STATCOM can result in excellent current and voltage waveforms as well as very short response time while operating at a low switching frequency. This makes the proposed scheme suitable for high power applications. [ABSTRACT FROM PUBLISHER]