Photovoltaic Constant Power Control via Dynamic Voltage Reference
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Solution Overview
Problem
Existing photovoltaic systems face challenges in maintaining constant output power due to rapid changes in solar irradiance, leading to oscillations and low response rates in voltage step-based constant power generation control methods, which can result in overload phenomena and unstable grid operation.
Innovation Solution
A method and apparatus for real-time constant power point tracking in photovoltaic systems, using a CPG control method that estimates the photovoltaic panel terminal voltage reference close to the constant power point without voltage steps, allowing for rapid convergence and preventing oscillations, thereby maintaining constant output power even under rapid solar irradiance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If voltage step-based CPG control is used to maintain constant output power, then the control method is simple to implement, but oscillations occur around the constant power point and response rate is low when solar irradiance changes rapidly
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the output power of the photovoltaic system and adjusts the operating point accordingly. When the output power deviates from the constant power point due to solar irradiance changes, the controller detects this deviation and modifies the duty cycle of the DC-DC converter to bring the power back to the set point, thereby eliminating oscillations and improving stability.
Solution Approach 2:
The patent transitions from a static voltage step-based control to a dynamic control approach where the operating voltage is continuously adjusted based on real-time power measurements. The controller dynamically modifies the duty cycle in response to changing solar irradiance conditions, enabling the system to adapt quickly to environmental changes while maintaining constant power output without oscillations.
2Device complexity
If voltage step-based CPG control is used, then the control structure is simple, but the response rate is low when solar irradiance changes rapidly
Solution Approach 1:
The controller continuously monitors output power and compares it with the reference constant power value. When solar irradiance changes cause power deviation, the feedback mechanism immediately detects this and adjusts the duty cycle accordingly, enabling rapid response to environmental changes while maintaining a relatively simple control structure based on standard PWM controllers and DC-DC converters.
3Reliability
If limit output power value is strictly enforced to prevent grid overload, then grid stability is improved, but power generation efficiency is reduced during peak solar irradiance periods
Solution Approach 1:
The patent changes the operating parameters (voltage and current) of the photovoltaic system dynamically while maintaining constant power output. By adjusting the duty cycle of the DC-DC converter, the system can operate at different voltage-current combinations that all result in the same constant power output, thereby preventing grid overload while maximizing power generation efficiency during peak solar irradiance periods.
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
This approach enables high-response-rate constant power generation, preventing overload and ensuring stable and economical grid operation by efficiently managing peak power periods and reducing oscillations around the constant power point, thus enhancing the reliability and economic feasibility of photovoltaic systems.
Implementation Method 1
photovoltaic systems are capable of generating eco-friendly power energy from infinite solar energy
Data Source
AI summary
Disclosed is an apparatus including: a photovoltaic panel; a CPG controller configured to receive a limit output power value of a photovoltaic panel, a photovoltaic panel terminal voltage, and a photovoltaic panel output current and output a photovoltaic panel terminal voltage reference; a direct current (DC)-voltage controller configured to receive the photovoltaic panel terminal voltage reference and the photovoltaic panel terminal voltage and output a duty ratio to cause an error between these values to become zero; a pulse width modulation (PWM) control signal generator configured to receive the duty ratio and output a PWM signal to control a DC/DC converter connected to the photovoltaic panel; the DC/DC converter configured to receive the PWM signals and perform CPG control; and a DC/AC inverter connected to the DC/DC converter and configured to convert DC power into AC power and output the AC power to an electrical grid.