PV Optimizer String Positioning via Active Voltage Difference
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Solution Overview
Problem
In photovoltaic power generation systems with optimizers, the inverter struggles to accurately determine the topological information of optimizers, leading to potential crosstalk issues and incorrect master node determination, which can result in over-voltage damage.
Innovation Solution
An optimizer positioning method is introduced, where the inverter sets output voltage and current limit values for each optimizer, controls them to start, and actively changes the output voltage of optimizers in parallel-connected photovoltaic strings without voltage difference to create a voltage difference, allowing the inverter to determine the photovoltaic strings based on electrical states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the inverter manually enters topological information of optimizers, then the system can identify optimizer positions, but the process is time-consuming and error-prone
Solution Approach 1:
The system enables automatic identification of optimizer topological information through self-service mechanisms. The inverter automatically detects and records the positions of optimizers in parallel-connected photovoltaic strings without requiring manual intervention, thereby eliminating time-consuming manual entry processes while maintaining accurate topological information.
Solution Approach 2:
The system performs preliminary actions by pre-establishing identification markers or unique identifiers for each optimizer before the actual positioning process. This preliminary preparation enables the inverter to automatically recognize and record optimizer positions during system initialization, avoiding the need for manual entry during operation.
2Device complexity
If the inverter does not acquire topological information of optimizers, then the system operation is simplified, but crosstalk problems occur leading to incorrect master node determination
Solution Approach 1:
The system introduces an intermediary identification mechanism that facilitates accurate communication between the inverter and optimizers. This intermediary layer provides unique identifiers or address information that enables the inverter to correctly distinguish between different optimizers in parallel strings, preventing crosstalk issues while maintaining reliable master node determination without excessive system complexity.
3Ease of manufacture
If the inverter only implements correspondence between optimizers and Boost circuits, then the system configuration is simplified, but the inverter cannot determine long strings leading to over-voltage damage
Solution Approach 1:
The system transitions from a one-dimensional correspondence relationship (optimizer to Boost circuit) to a two-dimensional topological mapping that includes string position information. By adding the dimension of string identification and position tracking, the inverter can determine which optimizers belong to long strings versus short strings, enabling proper voltage management without complicating the basic configuration process.
Data Source
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AI summary
Provided in the present application are a photovoltaic system and an optimizer positioning method therefor. The optimizer positioning method comprises: firstly, an inverter setting an output voltage limit value and/or an output current limit value for an optimizer in each photovoltaic string, and controlling each optimizer to start; and then, for a parallel voltage-difference-free photovoltaic string connected to a boost circuit, the inverter controlling one of the optimizers at least once to change an output voltage, actively making an inter-string voltage difference for the parallel voltage-difference-free photovoltaic string, and then constructing a long string and a short string, which are connected in parallel, so as to form a loop. Since a loop may cause the electrical states of optimizers in a long string and a short string to be different, photovoltaic strings to which the optimizers respectively belong can be distinguished according to the electrical states of the optimizers, such that the optimizers between different photovoltaic strings connected to a boost circuit are automatically distinguished, and string level positioning of the optimizers is also realized.