Power Converter Synchronizer for Grid Phase Alignment
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Solution Overview
Problem
Current synchronization methods for generation units and microgrids in electric power systems are slow and reliant on communication, limiting dynamic adaptation and prone to transients due to slow mechanical dynamics and uncontrolled phase angles, especially in systems with high harmonic and unbalance errors.
Innovation Solution
Implementing a power converter-based synchronizer that actively regulates phase and frequency by injecting or extracting active and reactive power, using phase-locked loop (PLL) techniques to synchronize generators or microgrids with the power system, thereby eliminating the need for long-distance communication and enhancing synchronization speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency and voltage control of generation units is used for synchronization, then synchronization is achieved, but the process is slow due to steady-state design and mechanical dynamics
Solution Approach 1:
The patent replaces the traditional mechanical frequency and voltage control systems with a power electronic converter-based synchronizer. The converter uses electronic control to directly regulate the output frequency and voltage, eliminating the slow mechanical dynamics of traditional generator control systems. This substitution enables rapid adjustment of synchronization parameters without being constrained by mechanical inertia and response times.
Solution Approach 2:
The patent changes the control parameters from steady-state frequency and voltage regulation to dynamic synchronization parameter control. The synchronizer actively adjusts frequency, voltage magnitude, and phase angle in real-time to match the grid parameters, enabling fast synchronization. The system transitions from passive steady-state operation to active dynamic parameter adjustment.
2Reliability
If secondary control is used for microgrid synchronization, then synchronization parameters are regulated, but communication requirement increases device complexity and time is extended to several minutes
Solution Approach 1:
The patent implements a self-service synchronization approach where the converter-based synchronizer autonomously regulates synchronization parameters using only local measurements from the point of common coupling. The system independently adjusts its output to match grid parameters without requiring communication with other generation units or centralized control, eliminating communication infrastructure and reducing system complexity.
Solution Approach 2:
The patent segments the synchronization function from the traditional hierarchical control structure (primary and secondary control). Instead of relying on centralized secondary control that coordinates multiple units through communication, the synchronizer performs synchronization as an independent, localized function at the converter level, separating it from the overall microgrid control architecture.
3Device complexity
If phase angle is left uncontrolled during synchronization, then frequency control can be simplified, but phase matching becomes indirect and synchronization time becomes highly variable
Solution Approach 1:
The patent introduces active feedback control of the phase angle through the converter-based synchronizer. The system continuously monitors the phase difference between its output and the grid voltage, and dynamically adjusts the output phase to minimize this difference. This direct phase control provides deterministic synchronization timing, eliminating the variability associated with indirect phase matching methods.
Solution Approach 2:
The patent performs preliminary phase alignment by actively controlling the phase angle before breaker closure. The synchronizer pre-adjusts the phase of its output voltage to match the grid phase, ensuring that when the breaker closes, the phase difference is already within the acceptable window. This eliminates the need for waiting periods and frequency offset adjustments used in traditional methods.
Data Source
AI summary
A power system including a first grid and a second grid, each grid having power flow parameters. A breaker installed at a point of common coupling between the first grid and second grid. A first sensor and a second sensor, each located on a side of the point of the common coupling for continually determining the power flow parameters of the first grid and second grid. Wherein the power flow parameters for the first and second grid are indicative of a frequency and a phase. A power source for supplying power to either the first grid or second grid. A controller for synchronizing the frequencies and the phases of the first and second grid, by continually adjusting an amount of power supplied, based on continually determining a frequency mismatch and a phase mismatch between the first grid and second grid, until a first predetermined condition is met.