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Self-synchronized converter for fast synchronization between low voltage microgrid and inverter connection

Amin, Md Ruhul (2017) Self-synchronized converter for fast synchronization between low voltage microgrid and inverter connection. Masters thesis, Universiti Tun Hussein Onn Malaysia.


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In this research, a fast-synchronization between single-phase microgrid and inverter in low voltage, which is based on virtual synchronous converter (VSCon) technique is been developed. This technique does not require any phase locked loop (PLL) circuit as an external control structure for the synchronization of the inverter. As known, PLL is a common technique in order to synchronize the amplitude, phase-angle and frequency between a microgrid and an inverter in distributed generation network. Previous studies show that, the disadvantage of PLLs is where the non-linear characteristic on the signal process will result the inverter control to be non-linear. Therefore, it is difficult and lengthy process to tune the PLL gains to reach suitable performance in order to synchronize the voltage, phase-angle and frequency between microgrid and inverter. As a result, a VSCon is been developed in which it is a selfsynchronized inverter which is based on synchronous generator mathematical model. This controller acts like as synchronous generator operating system in inverter control loop in order to achieve fast voltage, phase and frequency synchronization between inverter-microgrid connection. This technique has been modeled, simulated and tested in Matlab/Simulink software. It is by using a single-phase AC source input system connecting with several load variations during simulation period. This VSCon has been placed in inverter control loop to generate a pulse width modulation (PWM) signal that responds to the grid information for to synchronizing the inverter output voltage with the grid voltage. A single source input at 120V, 50Hz frequency and 240V, 50Hz frequency are used in order to see the self-synchronization response between a microgrid and an inverter. Furthermore, it also been tested when the grid frequency has been changed from the rated frequency at 50Hz to 51Hz and the result shows that, VSCon takes nearly 1-cycle to synchronize to this new frequency value. The grid phase angle test also has been conducted. For this test, the voltage grid which has 100 phase delay has been created in the input voltage source at microgrid side. As a result, the VSCon is also able to achieve self-synchronization with this new source input phase delay in just within 1.5 cycles or 30ms after the inverter has been connected to the microgrid. From all the results that have been collected, this technique can be an improved model for inverter to have synchronization between inverter and microgrid which is not require a PLL circuitry model in order to maximize the power transfer from the inverter to the microgrid when it been applied to the distributed generation network.

Item Type: Thesis (Masters)
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK2000-2891 Dynamoelectric machinery and auxiliaries
Depositing User: Mr. Mohammad Shaifulrip Ithnin
Date Deposited: 27 Mar 2018 03:35
Last Modified: 27 Mar 2018 03:35
URI: http://eprints.uthm.edu.my/id/eprint/9912
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