Single Phase Power System Controller Harmonic Reduction
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Solution Overview
Problem
Conventional single-phase grid-connected distributed generation systems face challenges such as slow system response, computational complexity, sensitivity to uncertainties, and harmonic complexities due to the need for ninety-degree phase-shift operations and separate control of active and reactive powers.
Innovation Solution
A single-phase power system controller that generates an error signal from instantaneous power references and modulates it based on the grid voltage phase angle, eliminating the need for phase-shift operations and allowing direct control of instantaneous power, with harmonic compensation loops to reduce grid current harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ninety-degree phase-shift operation is used to generate dq components in single-phase systems, then active and reactive power control can be achieved, but system response speed decreases and stability margins reduce
Solution Approach 1:
The patent extracts and eliminates the ninety-degree phase-shift operation block from the control system. By directly using the single-phase voltage and current signals without synthesizing a quadrature component, the patent removes the source of slow dynamics while preserving the ability to control active and reactive power through modified control algorithms that work directly with the available signals.
Solution Approach 2:
Instead of following the conventional approach of generating dq components through phase-shift operation, the patent inverts the methodology by directly computing power components from the available single-phase signals. The control strategy is reversed to work with the fundamental frequency components directly rather than transforming them through a phase-shifted reference frame.
2Ease of operation
If ninety-degree phase-shift operation is implemented using time-delay or filtering methods, then dq transformation can be performed, but computational complexity increases and stability margins decrease
Solution Approach 1:
The patent removes the complex phase-shift operation blocks (time-delay elements, all-pass filters, Hilbert transforms, SOGI, or EPLL) from the control architecture. By eliminating these computationally intensive components, the patent significantly reduces the computational burden while maintaining the essential power control functionality through direct calculation methods.
3Ease of operation
If separate control of active and reactive powers is implemented in single-phase systems, then power injection can be controlled, but control algorithm sensitivity to system uncertainties increases
Solution Approach 1:
The patent merges the separate active and reactive power control loops into a unified control framework that simultaneously handles both power components. By combining the control strategies and using a unified approach to generate the reference current signal, the patent reduces the cumulative sensitivity to parameter uncertainties that arises from having separate control algorithms.
4Ease of operation
If conventional single-phase control strategies are used, then grid connection can be achieved, but harmonic injection into the grid increases
Solution Approach 1:
The patent employs periodic control action synchronized with the grid frequency to actively compensate for harmonics. By using phase-locked loop synchronization and generating reference signals that are precisely synchronized with the grid voltage, the patent creates periodic control actions that cancel out harmonic components and prevent their injection into the grid.
Data Source
AI summary
Provided herein is a single phase power system controller and a method for controlling a single phase power system. The single phase power system controller comprises an error signal generator that generates an error signal from an instantaneous power reference signal and a measured instantaneous output power signal corresponding to the power delivered to a power distribution grid; and a modulator that modulates the error signal according to a trigonometric function of the grid voltage phase angle and produces a control signal for an inverter controller. In accordance with the circuits and methods provided herein, real and reactive power delivered to the grid are controlled simultaneously based on instantaneous output power feedback.