PV Converter Voltage Limiting That Preserves MPPT Power Output
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In photovoltaic power generation systems, the implementation of a voltage-limited output in existing converter control methods can lead to a situation where the power of a photovoltaic string drops to zero, affecting energy yield and system stability due to the fixed voltage limiting method used to prevent overvoltage and inverter failure.
Innovation Solution
A converter control method that simulates an output power-voltage curve with a simulated voltage limiting section and a constant power section, allowing the inverter's existing MPPT control policy to adapt, ensuring stability and increasing energy yield by making the photovoltaic module equivalent to a new module from the inverter's perspective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed voltage limiting method is used to prevent overvoltage and inverter failure, then system reliability is improved, but power output may drop to zero affecting energy yield
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed voltage limiting method to a dynamic voltage limiting method. The voltage limiting point is no longer fixed but dynamically adjusted based on the actual power output characteristics of the photovoltaic module. This allows the system to adapt the voltage limit in real-time, preventing overvoltage while maximizing power output, thus resolving the contradiction between reliability and energy yield.
Solution Approach 2:
The patent changes the parameter of voltage limiting from a fixed value to a variable value that depends on the power-voltage characteristics of the photovoltaic module. By continuously adjusting the voltage limiting point according to the actual power output, the system maintains reliability while avoiding unnecessary power loss, thereby improving energy yield without compromising system safety.
2Adaptability or versatility
If converter performs voltage-limited output to increase photovoltaic module configuration flexibility, then adaptability is improved, but power output may be reduced affecting energy yield
Solution Approach 1:
The patent makes the voltage limiting parameter dynamic rather than fixed, allowing it to adjust according to the photovoltaic module's power-voltage characteristics. This dynamic adjustment maintains configuration flexibility while maximizing power output at each operating condition, thus improving energy yield without sacrificing adaptability.
Solution Approach 2:
The patent implements a feedback mechanism where the voltage limiting point is continuously adjusted based on the actual power output of the photovoltaic module. This feedback loop ensures that the voltage limit adapts to changing operating conditions, maintaining both configuration flexibility and maximum energy yield by preventing excessive voltage while allowing optimal power extraction.
Data Source
AI summary
This application relates to a converter in a photovoltaic power generation system and a converter control method. An input end of the converter is connected to at least one photovoltaic module, and an output end is connected to an inverter. The control method includes: determining an output power-voltage (PV) curve of a converter based on an output PV curve of the photovoltaic module; and controlling a voltage output of the converter based on the output PV curve of the converter. The output PV curve includes at least a simulated voltage limiting section and a constant power section that are connected. In this application, an existing MPPT control policy of the inverter can be adapted when a voltage-limited output is implemented, to avoid a case in which a power of a photovoltaic string drops to zero.