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Compensation in Power System
Published in Amitava Sil, Saikat Maity, Industrial Power Systems, 2022
Static Synchronous Compensator (STATCOM) – A STATCOM generally consists of a voltage source converter that is used to convert the DC input voltage to an AC output voltage, a DC capacitor for supply of constant DC voltage of the voltage source converter, an inductive reactance which is a transformer connected between the output of voltage source converter and power system and a harmonic filter, which has operating principle, similar to those of rotating synchronous compensators (i.e. generators), but with relatively faster operation. Since in the STATCOM, the voltage source is created from a DC capacitor, STATCOM has very little active power capability. For dynamic compensation that facilitates enhanced voltage stability by providing reactive power support to the power system, STATCOM is preferred over SVCs in view of faster response and requirement of less space. The reactive power compensation provided by STATCOM is more than SVCs because at a low voltage limit, the reactive power drops off as the square of the voltage for the SVCs, but drops off linearly with the STATCOM. STATCOM at reduced voltage can still maximum current, whereas SVC current capability reduces in proportion to voltage. As a result, STATCOM has superior dynamic response, and for comparison, STATCOM may be rated for 75% of SVC rating for same performance in response to line fault. Active voltage control is possible with a STATCOM. This could further help with system stability control. The schematic diagram of STATCOM is shown in Figure 19.4 using voltage source convertor.
Microgrids—A Future Perspective
Published in Baseem Khan, Sanjeevikumar Padmanaban, Hassan Haes Alhelou, Om Prakash Mahela, S. Rajkumar, Artificial Intelligence-Based Energy Management Systems for Smart Microgrids, 2022
Akhil Gupta, Kamal Kant Sharma, Gagandeep Kaur
STATCOM is a static compensator that comprises invertors and a transformer with an ability of controlling dynamic stability. Its operation can be relatively compared with dynamic compensator as it is synchronous in nature and has a feature of generating reactive power in a sufficient way in the case of non-availability of moving parts. It has been seen that its usage is more dominant in renewable energy sources, especially solar power plants in which reactive power is required for active power to flow and controlled due to the absence of moving parts and output deliverable in constant power supply. Active and reactive power control can easily be addressed between two different voltage ends as it also gives a difference in critical angle stability and also stabilizes frequency variations in a system [31]. Reactive power can be controlled by changing the voltage profile or having a sufficient voltage difference but active power operation in a steady state is zero to keep inverter losses at a minimum and neglected in a operation where the condition is being maintained by other equipment of a device [32–34].
Frequency and Voltage Control
Published in Antonio Gómez-Expósito, Antonio J. Conejo, Claudio A. Cañizares, Electric Energy Systems, 2018
Claudio A. Cañizares, Carlos Álvarez Bel, Göran Andersson
In comparison with the SVC, the STATCOM offers two advantages. First, the STATCOM's output reactive current is not limited at low- or high-voltage conditions; rather, the output current is only limited by the converter ratings and is not dependent on the system voltage. This means that the reactive support during extreme voltage situations is much better with respect to the SVC, as shown in Figure 9.37. Second, the control response is much faster, since it is limited by the switching frequency of the VSC (usually around 1 kHz). The STATCOM can hence be used to reduce flicker and other fast voltage variations effectively.
Conformable Fractional Order Controller Design and Implementation for Per-Phase Voltage Regulation of Three-Phase SEIG Under Unbalanced Load
Published in Electric Power Components and Systems, 2022
In order to regulate the output voltage of SEIG, researchers employed different type of Flexible AC Transmission System (FACTS) such as synchronous condenser, Static VAr Compansator (SVC) and Static Synchronous Compensator (STATCOM). Despite the advantages of fast response and low harmonics generation, STATCOM has high investment costs. On the contrary, fixed-capacitor thyristor-controlled reactor (FC-TCR) which is a type of SVC has low investment costs and simple controllable structure. Moreover, it reduces power fluctuations. Taking the rural area conditions into account, FC-TCR can be preferred to regulate the SEIG’s output voltage because of its aforementioned advantages compared to the synchronous condenser and STATCOM [6]. Chermiti proposed a SEIG frequency regulator based on TCR circuit to compensate the reactive power [7]. They proposed a method for determining the appropriate excitation capacitor values required for various load conditions. Ahmed et al presented a study includes Static Volt Ampere Reactive Compensator (SVC) based SEIG voltage regulator [8]. A PI controller is used in this study to adjust the capacitance value of the SVC. The results prove the SVC's success in regulation of the output voltage of the SEIG in simulation and experiments.
A Capacitor Voltage Balancing Scheme for a Single-Phase Cascaded H-Bridge STATCOM
Published in Electric Power Components and Systems, 2018
Yarlagadda Srinivasa Rao, Mukesh Kumar Pathak
The static synchronous compensator (STATCOM) is used in the transmission lines to regulate the line voltages and to increase the active power flow. The voltage source converter (VSC) suitable for STATCOM is realized by (i) Two level converter and a line frequency transformer, (ii) multi-pulse converters, and (iii) multi-level converters. The line frequency transformer is costly, bulky, and lossy, so this type of converter is not preferred for medium voltages. The multi-pulse static converter can be used for shunt compensation [1] but due to the requirements of the complex phase shifting transformer, the multi-pulse converter is also less preferred. Owing to the disadvantages of transformers, the multi-level converters [2–28] are preferred for the medium voltage and high power applications. The basic topologies in multi-level converters are diode-clamped converters, flying capacitors converters, and cascaded H-bridge (CHB) converters. In realizing the shunt compensators, generally CHB multi-level converters are used [2–28]. The major advantage of cascaded multi-level converter is its modular structure, which is easy for both maintenance as well as future extension.
Determination of Maximum Loadability by a Mixed Complementarity Formulation of the Adjusted Power Flow Problem
Published in Electric Power Components and Systems, 2018
Sunil S. Damodhar, Krishna Suryanarayan
The STATCOM is a voltage source converter-based FACTS controller which can supply variable reactive power and control the voltage of the bus to which it is connected. The steady-state characteristic of a STATCOM is shown in Figure 5(b) [22]. The limits on the STATCOM current Ist are (capacitive) and (inductive). The additional set of relations due to the presence of STATCOM is exactly one of the following: where is the STATCOM voltage when Ist = 0 and Vst is the voltage of the bus to which the STATCOM is connected. The slope of the control range is Xs. The STATCOM can be included in the power flow problem by treating Ist as a variable and solving (6) along with (1). The reactive power injected by the STATCOM, equal to − VstIst, has to be included in (1b).