Shahed University

Active Parallel Power Decoupling Circuit for Single Stage AC-PV Modules

Naser Ghasemi | Mehdi Akhbari

Date :  2017/10/23
Publish in :    کنفرانس - سي و دومين کنفرانس بين المللي برق

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Keywords :Parallel, Power, Single, Modules

Abstract :
—AC photovoltaic modules due to several advantages in compare to centralized PV systems and string PV systems are future trend. Microinverters are important component of an ACPV module. Output power at single phase single stage grid connected microinverters is pulsating with twice grid voltage frequency whereas the PV module produced power is constant. In conventional design a power decoupling capacitor handle difference input and output power, this causes the PV current and the power decoupling capacitor voltage be fluctuating. This problem influences the operation of maximum power tracking of PV module and increases output current THD. However a bulky PV side power decoupling capacitor can reduce voltage ripple; but using a big electrolytic capacitor reduces converter lifetime and system reliability and as well as increases microinverter volume and cost. In this paper a novel parallel power decoupling circuit based on flyback topology is proposed to reduce the decoupling capacitor size and voltage ripple. This circuit operates as a controlled current source in parallel with PV module. Proposed circuit controller is independent from main microinverter and utilizes a simple control strategy without any additional sensor. By employing proposed circuit on flyback microinverter, low frequency voltage fluctuating is mitigated without usage of a big capacitor. For verifying proper operation of the proposed circuit, the whole of the flyback microinverter with active decoupling circuit as well as their control circuits are modeled in PowerSim software, the circuit operation is simulated. Proper functioning of the circuit and the expected performances issued from simulation results proved in all conditions.

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