Power Control System for Unbalanced Grid Synchronization
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Solution Overview
Problem
Existing power grid synchronization systems, such as phase lock loops (PLLs), are ineffective in maintaining synchronization with unbalanced power sources, leading to inefficiencies in power transmission and distribution.
Innovation Solution
A power control system that decomposes three-phase power into positive-sequence components using a tracking filter and phase locked loop (PLL), generating balanced quadrature signals and tracking rotational frequency or speed to synchronize power signals, even in the presence of unbalanced power sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional phase lock loops (PLLs) are used for synchronization, then synchronization is achieved under balanced conditions, but synchronization fails under unbalanced power source conditions
Solution Approach 1:
The patent segments the three-phase power signals into positive-sequence and negative-sequence components using a decomposition network. This segmentation allows the PLL to specifically track the positive-sequence components which represent the balanced portion of the unbalanced power source, thereby achieving reliable synchronization even when the overall power source is unbalanced.
Solution Approach 2:
The patent introduces a decomposition network as an intermediary between the power source and the PLL. This intermediary separates the useful positive-sequence components from the harmful negative-sequence components, allowing the PLL to synchronize only with the balanced portion of the power source while ignoring the unbalanced portion.
2Speed
If PLLs respond to both frequency and phase of input signals, then frequency matching is achieved, but dynamic fluctuations increase under unbalanced conditions
Solution Approach 1:
The patent extracts only the positive-sequence components from the three-phase power signals using a decomposition network. By taking out only the balanced portion of the power source for PLL processing, the system achieves rapid frequency matching while eliminating the destabilizing influence of negative-sequence components, thus maintaining synchronization stability under unbalanced conditions.
3Productivity
If synchronized AC power transmission is implemented, then power transmission efficiency is improved, but synchronization is disturbed by unbalanced power sources
Solution Approach 1:
The patent implements a feedback mechanism where the decomposition network continuously analyzes the three-phase power signals and separates positive-sequence components, which are then fed to the PLL for synchronization. The PLL uses this feedback to continuously adjust and maintain synchronization with the balanced portion of the power source, ensuring reliable power transmission even under unbalanced conditions.
Data Source
AI summary
A system and method for controlling an electrical device is provided. The method comprises receiving three phase power from a source, decomposing signals representative of power in each phase of the three phase power to provide a positive-sequence component of each phase and tracking the positive-sequence component of each phase via a phase locked loop and a tracking filter.