PV Optimizer Voltage Control for Inverter Startup
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Solution Overview
Problem
Photovoltaic power generation systems with optimizers face challenges in rapid shutdown during emergencies and start-up issues due to communication interference and reliance on traditional communication methods, leading to potential damage and economic losses.
Innovation Solution
A photovoltaic power generation system comprising a string of optimizing modules with a control unit and an auxiliary detection module that allows for autonomous control of output voltage and current, enabling safe start-up and rapid shutdown without traditional communication with the inverter, using power resistors or a controllable current source to manage voltage and current conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional communication methods (modem circuit) are added to achieve rapid shutdown, then shutdown capability is improved, but system cost increases and communication reliability deteriorates due to interference
Solution Approach 1:
The patent extracts the communication function from the traditional modem-based system and replaces it with direct electrical signal transmission through the existing power lines. The inverter directly detects voltage changes from the optimizing modules without needing separate communication circuits, eliminating the modem component and its associated interference problems while maintaining rapid shutdown capability
Solution Approach 2:
The patent uses the power line itself as an intermediary carrier for both power transmission and control signaling. The voltage signals generated by the optimizing modules serve as both the control command and the communication medium, eliminating the need for separate communication infrastructure and reducing system complexity
2Reliability
If optimizers wait for inverter start-up before operating, then system stability is improved, but startup time increases and power generation is lost during cloud/shadow periods
Solution Approach 1:
The patent enables optimizing modules to perform preliminary actions by generating voltage signals before the inverter is fully operational. The modules can detect inverter status through voltage detection and adjust their output accordingly, allowing them to prepare and start generating power as soon as conditions permit, rather than waiting for complete system initialization
Solution Approach 2:
The optimizing modules possess self-service capability through integrated voltage detection and control functions. Each module can independently detect system conditions and adjust its own output voltage to match inverter requirements, enabling autonomous operation without requiring centralized control or waiting for explicit start-up commands
3Productivity
If optimizers output voltage immediately during startup, then power generation starts earlier, but inverter damage may occur due to excessive voltage
Solution Approach 1:
The patent implements feedback control where the inverter detects the voltage output from optimizing modules and provides feedback signals back to the modules. The optimizing modules continuously monitor system voltage conditions and adjust their output voltage in real-time based on feedback, ensuring voltage remains within safe ranges while enabling early power generation
Solution Approach 2:
The patent employs dynamic voltage adjustment where the optimizing modules continuously adapt their output voltage based on real-time system conditions. The voltage output is not fixed but dynamically adjusted according to inverter startup stage and system requirements, allowing early operation while preventing damage through continuous adaptation
Data Source
AI summary
The invention discloses a photovoltaic power generation system and a method for controlling the same. The photovoltaic power generation system comprises: an string of optimizing modules and an inverter, the string of optimizing modules comprises a plurality of optimizing modules each having an input port coupled to at least one photovoltaic module, output ports of the plurality of optimizing modules are connected in series, each of the optimizing modules comprises a control unit, an input port of the inverter is coupled to an output port of the string of optimizing modules, and the inverter comprises an auxiliary detection module for auxiliary detecting an output current of the string of optimizing modules, and the control unit controls an output voltage of the string of optimizing modules based on the output current of the string of optimizing modules, such that the output voltage satisfies a start-up condition of the inverter.