Inverter MPP Tracing via Counterweight Power Compensation
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Solution Overview
Problem
Existing power generation networks face challenges in stabilizing the electricity grid by efficiently derating renewable energy sources, as they require frequent determination of the Maximum Power Point (MPP) to adjust power output, leading to high communication overhead and potential instability, especially when inverters are far apart.
Innovation Solution
An inverter system that minimizes communication overhead by allowing inverters to compensate for power deviations during MPP determination through coordinated power profiles, where one inverter traces the characteristic curve and others adjust their output to compensate, reducing the overall power deviation from the derated value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If one inverter traces the characteristic curve to determine MPP, then the MPP power value is determined, but the power deviation from derated power increases
Solution Approach 1:
The patent applies the counterweight principle by having other inverters generate compensating power with opposite sign to offset the power deviation caused by the scanning inverter. When one inverter deviates from derated power to trace the characteristic curve, other inverters adjust their power output in the opposite direction to maintain overall power stability at the derated level.
2Measurement precision
If frequent MPP determination is performed, then the maximum power is accurately known, but communication overhead increases
Solution Approach 1:
The patent merges the MPP determination function into a distributed system where any inverter can perform scanning when triggered by others. Instead of one central controller managing all MPP determinations, the system combines multiple inverters' capabilities, allowing them to share the scanning task and communicate only essential trigger signals and results, reducing overall communication overhead.
3Adaptability or versatility
If inverters are operated far apart in the network, then system redundancy is improved, but communication reliability deteriorates
Solution Approach 1:
The patent implements self-service by enabling inverters to autonomously perform MPP determination when triggered by peer inverters, rather than relying on continuous centralized control. Each inverter can independently scan and determine MPP, and the system uses decentralized trigger mechanisms where inverters autonomously initiate scanning cycles, reducing dependency on reliable long-distance communication for control signals.
Data Source
AI summary
An inverter for converting DC power of a generator into grid-conforming AC power includes an inverter bridge circuit and a scanning circuit configured to trace at least one part of a characteristic curve of the generator to determine an MPP power value (PMPP). The scanning circuit is configured, in the case of a derating to a derated power (Pred), to trigger a tracing of the characteristic curve with provision of a first power profile deviating from the derated power (Pred) if an enable signal is present at the inverter, and to indicate a start and an end of the tracing by outputting a start signal and an end signal, respectively. The scanning circuit is further configured to provide a second power profile as AC power upon receiving a start signal, wherein the first power profile has a deviation from the derated power (Pred) with a sign that is opposite to a sign of a deviation of the second power profile from the derated power (Pred).