3-Phase 4-leg unified series–parallel active filter system with ultracapacitor energy storage for unbalanced voltage sag mitigation

Author(s):  
Mehmet Ucar ◽  
Sule Ozdemir
2015 ◽  
Vol 2 (4) ◽  
pp. 1-6
Author(s):  
K. Venkateswarlu ◽  
◽  
B. Ashwin Kumar ◽  
N. Srinivas ◽  
V. Mallikarjuna Rao ◽  
...  

2019 ◽  
Vol 9 (3) ◽  
pp. 551
Author(s):  
Seyed Hakimi ◽  
Amin Hajizadeh

This paper develops modeling and describes a control strategy for a modular multilevel converter (MMC) for grid-connected renewable energy systems. The proposed model can be used to simulate MMC activity during normal and faulty situations. Firstly, a dynamic model of a grid-connected MMC (GC-MMC), based upon the symmetrical component of voltages and currents, was designed. Then an adaptive robust control approach was established in order to follow the reference currents of the converter and stabilize the submodule (SM) capacitor voltage. The positive and negative sequences of reference currents that were given from the demanded active and reactive power during grid voltage disturbance and a normal situation were then utilized in control loops. Finally, the numerical results for the performance of the MMC throughout voltage sag conditions and the effect of uncertainties on the filter parameters during changing power demands were evaluated. The results specified that the current control strategy is more potent under voltage sag situations and able to fulfill the stability requirements of the MMC.


Author(s):  
Tamilvanan G. ◽  
Mahendran S.

<p>In the power system the major issue is to maintain the power quality .The term of power quality is to maintain the disturbance less voltage to the power system. The voltage disturbance mainly caused by voltage sag, voltage swell and harmonics presented in the system. If the system voltage is going below to the nominal voltage, then it is called as voltage sag. These power quality (PQ) events typically last for less than one second. If the system voltage is going above the nominal voltage, there it is called as voltage swell. The AC-AC converter based DVR is proposed. It can properly compensate for unlimited time duration, balanced, and as well as unbalanced voltage sag by observing the power from the grid. The pulse width modulation technique is used to triggering the switches. Only by the simple Bidirectional switches were used for generate the compensation voltage.</p>


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