PV DC Series Boost Grid Power Balancer
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Solution Overview
Problem
Large-scale photovoltaic DC series boost grid-connected systems face issues of overvoltage and curtailment due to mismatches in input power among photovoltaic DC converters, leading to reduced system generating capacity.
Innovation Solution
A large-scale photovoltaic DC series boost grid-connected system with N photovoltaic DC converters and N−1 power balancers, where power balancers are placed between adjacent converters to balance input power, controlling current flow based on voltage differences to maintain equal output voltages and ensure maximum power point tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If photovoltaic DC converters are connected in series to reduce power conversion links and improve system efficiency, then system efficiency and cost are improved, but output overvoltage and curtailment occur due to input power mismatch among converters
Solution Approach 1:
The patent introduces a power balancer as an intermediary device between adjacent photovoltaic DC converters in series connection. The power balancer measures output voltages of connected converters and adjusts current distribution to balance input power among converters, thereby eliminating overvoltage and curtailment issues while maintaining the efficiency benefits of series connection.
2Productivity
If traditional AC grid connection is used for large-scale photovoltaic power stations, then power transmission is achieved, but harmonic resonance, inability to absorb and send power, and large-capacity reactive power compensation are required
Solution Approach 1:
The patent extracts and eliminates the AC conversion links from the traditional AC grid connection system by directly connecting photovoltaic DC converters to the DC grid in series. This removes the need for complex AC-DC conversion equipment, reactive power compensation devices, and eliminates problems associated with AC transmission such as harmonic resonance and limited power absorption capability.
3Productivity
If input power of photovoltaic DC converters is not balanced, then system operation continues, but generating capacity is reduced due to overvoltage and curtailment
Solution Approach 1:
The patent implements a feedback mechanism where the power balancer continuously measures the output voltages of photovoltaic DC converters and uses this information to adjust current distribution. The control unit receives voltage measurements, calculates the difference between converters, and automatically adjusts the power balancer to equalize input power, ensuring maximum generating capacity without manual intervention.
Data Source
AI summary
A large-scale photovoltaic direct current (DC) series boost grid-connected system with a power balancer, including N photovoltaic DC converters and N−1 power balancers, wherein N≥2. The output ends of the photovoltaic DC converters are connected successively in series and then connected to the DC grid, and the input ends of the photovoltaic DC converters are respectively connected to the output ends of the photovoltaic power generation unit. Among the photovoltaic DC converters, which are arranged successively in series, a power balancer is disposed between the input ends of two photovoltaic DC converters adjacent to each other. The N−1 power balancers are arranged corresponding to the set N−1 photovoltaic DC converters respectively to balance the input power of the corresponding photovoltaic DC converter, thereby eliminating a difference between the output voltages of the photovoltaic DC converters.