Power Conditioner Control for Neutral Line Offset Compensation
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Solution Overview
Problem
Existing power conditioners suffer from neutral line offset currents due to measurement errors in the current measurement module, leading to voltage deviations in capacitors and potential harm to the AC grid operation.
Innovation Solution
A power conditioner with a compensation computation mechanism in the control module that compensates for current measurement errors by subtracting target and feedback values, using proportional and integral amplifiers to generate a compensated control signal, eliminating offset currents at the neutral point without additional capacitor voltage control circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If independent phase current measurement and control is implemented, then real power and reactive power control of each phase is improved, but neutral line offset current is generated due to measurement errors
Solution Approach 1:
The patent introduces a feedback mechanism where the neutral line current is measured and fed back to the control module. The control module then adjusts the control signals to compensate for measurement errors, creating a closed-loop system that eliminates the accumulation of offset currents while maintaining independent phase control capability
Solution Approach 2:
The patent changes the control parameter by introducing a neutral line current compensation term into the control algorithm. By dynamically adjusting the control signals based on the measured neutral line current, the system compensates for measurement errors and prevents offset current accumulation without sacrificing independent phase control
2Device complexity
If measurement errors are not compensated, then device complexity is reduced, but capacitor voltage deviation occurs over time
Solution Approach 1:
The patent uses feedback of the neutral line current to detect measurement errors and automatically compensates for them in the control algorithm, maintaining capacitor voltage stability without adding complex hardware circuits. The feedback mechanism allows the system to self-correct measurement errors through software-based compensation
3Stability of the object's composition
If additional capacitor voltage control circuits are added, then capacitor voltage stability is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the control module multi-functional by integrating both the independent phase control function and the neutral line offset current compensation function into a single control unit. This eliminates the need for separate capacitor voltage control circuits, as the same control module performs multiple functions through software-based compensation
Solution Approach 2:
The patent replaces potential hardware-based capacitor voltage control circuits with a software-based compensation algorithm implemented in the control module. By using computational methods rather than additional physical circuits, the system achieves voltage stability without increasing device complexity or cost
Data Source
AI summary
A power conditioner with neutral line offset current compensation function, includes a power converter, a measurement unit, a control module, and two coupling capacitors connected through the neutral line to a three-phase AC grid. The power conditioner eliminates the offset current on the neutral line by compensating the inaccuracies in the measurement unit with the control module, thus minimizing the voltage deviation of the coupling capacitors. Compared to traditional control circuits, a feedback path is added to achieve the elimination of the neutral line offset current, suppressing unstable and unpredictable voltage fluctuations on the coupling capacitors without affecting the rated power transmission of the power converter, thus extending the lifespan of the coupling capacitors and enabling the power conditioner to operate more stably.