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The Static Synchronous Compensator (STATCOM) is increasingly popular in power quality application. The Voltage Source Inverter (VSI) based STATCOM is used for eliminating current harmonics and compensating reactive power. This VSI draw or supply a compensating current from the utility such that it cancels current harmonics on the AC side. STATCOM generates a current wave such that it compensate by...
Assuming that STATCOM has no active power losses, the current and voltage analytical expressions of the three-level and dual three-point STATCOMs under the fundamental frequency modulation (FFM) control are presented by means of the theoretical analysis method. Meanwhile, the current and voltage waveforms of two STATCOMs are simulated with the help of Matlab/Simulink. The good agreement between theoretical...
This paper proposes a new half-bridge inverter based active power quality compensator (APQC) for electrified railways with a three-leg inverter. The first-leg is connected to α-phase, and the second-leg is connected to β-phase. The midpoint of two capacitors on the dc side is connected to the ground line. These two half-bridge inverters exchange the active power on the each feeder each other through...
In recent years, voltage and current harmonic problems by the remarkable development of static power converters with nonlinear characteristics have been one of the significant subjects. The authors propose the three phase power quality compensator with five leg circuit by indirect power conversion method. This system can compensate the line voltage harmonics by the series inverter and the load current...
Three-phase currents of STATCOM with conventional control strategy will be unbalanced and distorted when the STATCOM operates at the condition of non-ideal grid voltages. Special attention was paid to the influence of grid voltage quality on STATCOM current and a new control strategy was presented to counteract the influence in this paper. The unbalance and non-sine distortion of grid voltage causes...
7 level cascaded voltage source inverter structure is presented as Static Synchronous Compensator (STATCOM). Selective harmonic elimination method, synchronous reference frame instantaneous reactive power theory method is applied. DC link capacitors voltage control algorithm is also used. Performance of STATCOM is examined in instantaneous load change from capacitive to inductive and vice versa. Rapid...
The power quality in distribution systems is affected by the pollution introduced by the customers. One way to improve the power quality is using a DSTATCOM to compensate reactive power and harmonics. The use of multilevel inverters in medium voltage applications is a good solution. In particular, the cascaded asymmetric multilevel converter (CAMC) appears as a very attractive alternative among the...
This paper presents the STATCOM using gradationally controlled voltage inverter. It consists of three inverter units connected in series, and each inverter unit generates a different output voltage such as Vc, 2 Vc, 4 Vc. This inverter can output 15 levels of voltage waveform by combinational output voltage of inverter units. The inverter units of output voltage 2 Vc, 4 Vc supply reactive power by...
This paper analyzes digital sensorless control systems used to regulate and to suppress harmonics on the output voltages of a self-excited squirrel-cage induction generator in isolated systems under nonlinear loads. A normalized discrete model of the inverter operated as static VAr compensator and active power filter are presented considering its implementation in a DSP TMS320F2812. Furthermore, the...
The static synchronous compensator (STATCOM) is a flexible ac transmission system(FACTS) device which can be used to generate reactive power in long distance ac power transmission. Cascade multilevel STATCOM is a so strongly coupled and nonlinear system that conventional linear control cannot assure a satisfactory behavior. In order to achieve high dynamic performance and robustness of control system,...
In distribution power system, the unbalanced operating state, harmonics, negative sequence components, which are caused by the nonlinear or unbalanced loads, not only increase the power transmission losses, but also are harmful to the electric devices. In this situation, the Active Power Filter (APF) and the Static Var Generator (SVG) would be required. However as proved in this paper, the existing...
Industrial plants are faced with stringent requirements enforced by the utility to meet power factor and power quality requirements. These plants, in order to avoid very costly penalties, have traditionally utilized switchable shunt capacitor banks with detuning reactors for power factor correction, along with a separate active harmonic filter in cases where harmonic currents are an issue as well...
Power systems use STATCOM for compensating purposes that is subjected to the high switching frequencies. Various PWM techniques make selective harmonic elimination possible, which effectively control the harmonic content of voltage source inverters. On the other hand, distribution systems have to supply unbalanced nonlinear loads, transferring oscillations to the DC-side of the converter in a realistic...
In this paper, a novel principle of a power quality conditioner based on controllable impedance is proposed for high voltage AC power distribution systems application. A linear transformer is employed to act as controllable impedance under the control of power electronic inverter. On the one hand, the transformer can always exhibit nearly zero impedance to harmonic current. Thus, the harmonic current...
The widespread use of non-linear loads and power electronics converters has increased the generation of non-sinusoidal and non-periodic currents and voltages in power systems. Reactive power compensation or control is an important part of a power system to minimize power transmission losses. Given a modulation index, the switch times can be chosen to achieve the fundamental while eliminating specific...
This paper deals with special active power line conditioner (APLC), which is based, the same as UPQC, on integration of series and shunt power converters sharing a common DC link. In this paper the main purpose of the shunt inverter is to compensate the reactive power and current harmonics caused by nonlinear load. In addition, a simple structure feed forward neural network is presented for the separate...
This paper presents the system analysis and circuit implementation of single-phase shunt-series compensator to improve voltage and current quality at the load side. The series compensator is adopted to compensate the voltage disturbance including voltage sag, swell, flicker and harmonics. The shunt compensator is used to supply the necessary active current to main the constant dc-link voltage of the...
The paper deals with the sliding mode control of inverter and its applications to custom power devices. Sliding mode control is used to control the voltage source inverter in voltage and current control mode. The sliding mode control strategies provide robustness to custom power device modeling with external disturbances. The proposed controller design is tested on a single phase dynamic voltage restorer...
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