Self-tuned fuzzy-proportional–integral compensated zero/minimum active power algorithm based dynamic voltage restorer
Voltage sag is the most common and severe power quality problem in the recent times due to its detrimental effects on modern sensitive equipment. Generally, direct-on-line starting of the three-phase induction motor (IM) and various kinds of short circuit fault are directly responsible for this event. This study investigates the impacts of starting and stopping of two three phase IMs on the load voltage profile. To be more critical, two three-phase short circuit faults and one unsymmetrical fault are also simulated in the same network at different instants of time. A simple control algorithm of a real power optimised dynamic voltage restorer (DVR) with a reduced power factor strategy is presented to protect the sensitive load from these types of detrimental events. A novel fuzzy-proportional–integral based self-tuned control methodology is implemented in the proposed work to compensate the loss in the DVR circuit as well as to regulate the load voltage and the direct current link voltage. The results show the effectiveness of the adopted control scheme in DVR application to mitigate the voltage sag.
- Dynamic Voltage Restorer
Fig. 1 Investigated distributed test system with DVR
EXPECTED SIMULATION RESULTS:
Figure 2. Voltage profile of load and DVR (a) Without DVR, (b) DVR voltage, (c) With DVR, (d) DC voltage
Figure 3 Torque profile of IMs (a) Motor 1without DVR, (b) Motor 2 without DVR, (c) Motor 1 with DVR, (d) Motor 2 with DVR
Figure 4. Pertaining to unsymmetrical fault (a) Load voltage without DVR, (b) DVR voltage, (c) Load voltage with DVR
Figure 5. Active DVR power profile pertaining to (a) In-phase compensation, (b) Present technique
This study divulges a simple yet robust reduced power factor controlled energy optimised algorithm in DVR to offer a common solution to mitigate the severe voltage sag. Minimisation of energy delivered may increase the life of the ESU, therefore limits the expenditure indirectly. The self-tuned fuzzy-Proportional-Integral scheme also plays a significant role to regulate the active power through the DVR as well as to compensate the load voltage and DVR losses. The results obtained in this work shows that the proposed DVR solution provides a good and satisfactory level of compensation. The system voltage has been compensated nearly up to its nominal value. The DC voltage is also very fairly regulated. The application of DVR reduces the level of oscillation in the torque profile of the IM. The proposed method is also compared with other strategies surfaced in the existing literature and it is unfold that the proposed strategy offers better harmonic compensation and it also provides better damping in the load voltage. Thus, it may be concluded that the proposed control technique of DVR, operated by adaptive fuzzy control scheme, may be justified for utilizing the same as a common sag mitigating device. Within the context of the present study, the work is ended with simulation only. However, the same may be tested on an experimental bench fuzzy-proportional-integral.
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