An improved IPT-PLL technology for single-phase grid-connected inverters in complex power grid conditions

Area of Science:

• Electrical Engineering
• Power Systems
• Control Systems

Background:

• Complex power grids face challenges with frequency variations and harmonic distortions.
• Single-phase converters in microgrids require robust phase-locked loop (PLL) technology.

Purpose of the Study:

• To propose an improved inverse Park transform phase locked loop (IPT-PLL) for single-phase converters in microgrids.
• To enhance adaptability to complex power grid conditions and improve tracking performance.

Main Methods:

• Utilizing the α component of Park transformation and a 1/4 fundamental period delay for phase detection.
• Employing Lagrange interpolation polynomials to approximate fractional delays, mitigating frequency change errors.
• Integrating multi-resonant controllers with proportional-integral (PI) regulators to suppress low-order harmonics.

Main Results:

• Demonstrated strong adaptability of the improved IPT-PLL to complex power grids.
• Significantly improved power grid frequency tracking performance.
• Effective suppression of low-order harmonic interference and DC bias, with good dynamic and static performance.

Conclusions:

• The proposed improved IPT-PLL offers superior performance in microgrid applications.
• It effectively addresses frequency variations and harmonic disturbances in complex power grids.
• The technology provides reliable dynamic and static characteristics for enhanced grid stability.