Islanding Detection via Periodic Harmonic Injection in Power Modules
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing islanding detection methods in power conversion systems, such as harmonic-injection, lead to increased total harmonic distortion (THD), causing performance degradations like lower power factor, higher peak currents, and reduced efficiency.
Innovation Solution
A module-based energy system with a master control device that periodically injects harmonic signals to detect islanding conditions by measuring output impedance, reducing THD and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If harmonic-injection islanding detection is used, then islanding detection capability is improved, but total harmonic distortion increases causing performance degradation
Solution Approach 1:
The patent applies periodic action by injecting harmonic signals only during specific detection intervals rather than continuously. The controller periodically switches between detection mode (injecting harmonic signal) and normal operation mode, thereby achieving islanding detection capability while minimizing the time during which THD is elevated, thus resolving the contradiction between detection reliability and harmonic distortion harm.
2Measurement precision
If continuous harmonic injection is used for islanding detection, then detection accuracy is improved, but THD and performance degradation increase
Solution Approach 1:
The system implements periodic detection cycles where harmonic injection is activated only when needed for islanding detection, followed by periods of normal operation without injection. This periodic approach maintains detection accuracy when required while significantly reducing the cumulative energy loss and performance degradation associated with continuous harmonic injection.
Solution Approach 2:
The patent applies partial action by using harmonic injection only to the extent necessary for reliable islanding detection, rather than maintaining continuous injection. The detection is performed in discrete intervals, applying the harmful harmonic signal only partially in time, thus achieving sufficient detection accuracy while minimizing the excessive energy loss and performance degradation that would result from continuous application.
Data Source
AI summary
Systems, devices, and methods for energy systems that include one or more modules are configured to connect to a power grid. Each module outputs a respective voltage waveform and/or a current waveform to a load. A controller is configured to periodically cause at least a portion of the one or more modules to output an increased voltage and/or current level at a specified harmonic frequency. An islanding detector is configured to detect, based on an impedance of the grid, when the one or more modules are in an island condition.