Sinusoidal AC Voltage Circuit for Photovoltaic PID Mitigation
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Solution Overview
Problem
Photovoltaic power generation systems face efficiency degradation due to the Potential Induced Degradation (PID) effect, which affects the performance and lifespan of solar cells, and existing solutions like pulse voltage compensation can cause environmental pollution and reduce the service life of photovoltaic strings.
Innovation Solution
A power supply circuit incorporating a switch, current-limiting device, capacitor, and CCFL conversion circuit that outputs a sinusoidal AC voltage with a small AU/At change, reducing electromagnetic pollution and prolonging the service life of photovoltaic strings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pulse voltage compensation is used to mitigate PID effects, then the cell performance can be restored, but the voltage waveform AU/At change is large causing electromagnetic pollution and reducing service life
Solution Approach 1:
The patent changes the voltage waveform parameters from traditional pulse voltage to sinusoidal AC voltage with specific frequency (50Hz) and controlled amplitude. This parameter change reduces the AU/At rate of change while maintaining the voltage compensation effect, thereby mitigating electromagnetic pollution and extending photovoltaic string service life while still restoring cell performance
Solution Approach 2:
The patent employs periodic sinusoidal AC voltage instead of single pulse voltage. The periodic nature of the sinusoidal waveform at 50Hz provides continuous compensation effect while the smooth curvature of the sine wave reduces abrupt voltage changes, thereby reducing electromagnetic radiation and harmful factors while maintaining reliability improvement
2Productivity
If components are connected in series to form higher system voltage, then power generation efficiency is improved, but leakage current accumulates charge causing PID effect and performance degradation
Solution Approach 1:
The patent applies voltage compensation through sinusoidal AC voltage before the PID effect causes severe performance degradation. By proactively compensating for the charge accumulation on cell surfaces, the system maintains component performance and prevents the deterioration of fill factor, short circuit current, and open circuit voltage while keeping the high voltage series connection configuration for efficiency
3Reliability
If negative bias is applied to discharge accumulated charge, then cell performance can be restored, but the circuit complexity increases
Solution Approach 1:
The patent uses a sinusoidal AC voltage source that can serve multiple functions: it provides voltage compensation to restore cell performance, it discharges accumulated charge through its alternating polarity, and it can be integrated with existing power supply infrastructure. This multi-functional approach achieves performance restoration without requiring separate complex discharge circuits
Solution Approach 2:
The sinusoidal AC voltage source automatically alternates between positive and negative cycles, self-regulating the charge discharge process without requiring complex control circuits. The inherent alternating nature of the sine wave provides automatic balance between charging and discharging, simplifying the overall circuit configuration while maintaining performance restoration capability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed power supply circuit effectively mitigates PID effects by providing a sinusoidal AC voltage that reduces environmental radiation and extends the lifespan of photovoltaic strings while being simple, cost-effective, and energy-efficient.
Implementation Method 1
the capacitor C1 is used to provide the operating voltage for the CCFL conversion circuit
Implementation Method 2
a CCFL conversion circuit that outputs a sinusoidal AC voltage
Data Source
AI summary
A power supply circuit and a photovoltaic power generation system comprising same. The power supply circuit utilizes the condition that a voltage output by discharge of a capacitor is a direct-current voltage which decreases with time, a CCFL conversion circuit is connected behind the capacitor, the CCFL conversion circuit converts the input direct-current voltage which decreases which time into a sinusoidal alternating-current for output. Since the CCFL conversion circuit operates in an open-loop mode, a peak-to-peak value of the sinusoidal alternating-current output by the CCFL conversion circuit is in direct proportion to an operating voltage of the CCFL conversion circuit, the voltage decreases with time, that is, the peak-to-peak valve of the sinusoidal alternating-current output by the CCFL conversion circuit decreases with time, thus, an effective value of the sinusoidal alternating-current decreases with time, and an attenuated sinusoidal alternating-current voltage is obtained.