Today, electricity is not only the main power of industry but also the main energy source indispensable for the people’s lives, and the demand is in a steady rise. Therefore, it is important for the power industry to reliably ensure the operation of power systems in a scientific and technological way.
The trend of global power system development is to establish and operate a flexible AC transmission system (FACTS) that can rapidly control the main characteristics of power system like voltage, frequency, active and reactive power, etc.
One of the important issues in establishing and operating such FACTS is to reduce the total harmonic distortion rate in power system equipment including reactive power compensators, for power quality.
Ri Tong Chol, a researcher at the Faculty of Electrical Engineering, has established a fuzzy logic controller for controlling the DC bus voltage of the converter to improve the response in a distribution grid static synchronous compensator (DSTATCOM) which is widely used in FACTS and to ensure normal operations of the compensator under asymmetric conditions and grid voltage variations, and verified its effectiveness through computer simulation tests.
For effective operation of DSTATCOM, the DC-side capacitor voltage of the voltage-type converter should be kept constant, and for this purpose, a fuzzy PI controller was used.
The simulation model of DSTATCOM was designed in a three-phase distribution system using SIMULINK tool in MATLAB environment and the performance of DSTATCOM with fuzzy logic control algorithms was simulated and analyzed under distorted PCC voltage due to unbalanced nonlinear load.
The harmonic distortion factors (THD) of the power supply current, load current and PCC voltage on A were measured to be 3.6%, 26.0% and 4.4%, respectively, using the proposed fuzzy logic controller of DSTATCOM.
The results confirmed that the controller performance improved with a power supply current of 3.6%, while the THD of PCC voltage was 4.4%.
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