Among the different disturbances affecting the power quality, the voltage sag are considered as a most important power quality problem faced by utilities, industrial consumer & equipment like PLC (Programmable Logic Controller), ASD (Adjustable Speed Drives) which need to be fully investigated. Custom power device are effective means for mitigating the voltage related issues prominently voltage sag, unbalanced load voltage, voltage regulation, sag/ swell etc. by compensating the reactive power with the injection of shunt current. Various DSTATCOM topologies & control scheme are suggested in the literature. In this paper by using three level H-bridge topology & five level cascaded multilevel inverter based DSTATCOM the voltage sag is compensated effectively with reduced total harmonic distortion (THD).
1. Cascaded Multilevel Inverter
3. Power Quality
Fig. 1. Three-phase, 3-level H-bridge inverter based DSTATCOM
Fig. 2. Three-phase, 5-level Cascaded H-bridge inverter based DSTATCOM
Fig. 3. System Block Diagram
EXPECTED SIMULATION RESULTS:
Fig. 4(a) Sag At Bus B3 (b) Injected Current By DSTATCOM (c) Compensated Voltage At Bus B3 (d)Active & Reactive Power At Bus B3 (e) Injected Active & Reactive (f) Compensated Active & Reactive Power at bus B3
Fig. 5 (a) Sag At Bus B3 (b) Injected Current By DSTATCOM (c) Compensated Voltage At Bus B3 (d)Active & Reactive Power At Bus B3 (e) Injected Active & Reactive (f) Compensated Active & Reactive Power at bus B3
Fig. 6(a) Phase voltage & Line voltage for 3-level inverter based DSTATCOM (b) Phase voltage & Line voltage for 5-level inverter based DSTATCOM
The paper presents the principle of operation of cascaded H-bridge converter and simulation studies on cascaded converter based DSTATCOM using Sinusoidal PWM control. It is observed that the DSTATCOM is capable of supplying the reactive power demanded by the load both during steady state and transient operating conditions. The harmonics in cascaded H-bridge five-level inverter current are less compared to three-level inverter operating at same switching frequency.
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