PV Inverter Control for Fast Grid Frequency Support
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Solution Overview
Problem
Current photovoltaic devices lack active support capabilities for power grid frequency and voltage, leading to system instability in high-penetration rate, large-scale, and long-distance photovoltaic transmission scenarios, and may result in disconnection during low-frequency or over-frequency events in the power grid.
Innovation Solution
A photovoltaic power generation system and control method that includes a direct current converter, an inverter, and an inverter controller. The controller generates drive signals based on voltage and power parameters to adjust the inverter's operating state, enabling the system to provide fast frequency support by converting direct current into alternating current and outputting it to the power grid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If photovoltaic penetration rate increases in the power grid, then photovoltaic power generation capacity increases, but system stability deteriorates due to lack of active support capability
Solution Approach 1:
The patent changes the operating parameters of the photovoltaic inverter to provide frequency support. Specifically, it adjusts the active power output of the inverter based on grid frequency deviations, enabling the photovoltaic system to actively support grid frequency while maintaining high penetration rates
Solution Approach 2:
The patent implements a feedback control mechanism where the inverter controller continuously monitors grid frequency and adjusts the active power output accordingly. When frequency deviation is detected, the controller modifies the inverter's power output to restore frequency, providing active support capability
2Device complexity
If photovoltaic device lacks active support capability, then device complexity is reduced, but power grid frequency stability deteriorates
Solution Approach 1:
The patent makes the photovoltaic inverter multi-functional by enabling it to perform both power generation and frequency support functions. The same inverter that converts DC to AC also actively supports grid frequency through controlled active power adjustment, eliminating the need for separate support devices
Solution Approach 2:
The photovoltaic system provides its own frequency support capability through the inverter controller that automatically detects frequency deviations and adjusts power output accordingly. The system serves itself by using its own controllable active power to stabilize the grid frequency
3Productivity
If photovoltaic transmission distance increases, then power generation capacity utilization increases, but system stability deteriorates due to long transmission line
Solution Approach 1:
The inverter controller implements real-time feedback control by continuously monitoring grid frequency and adjusting active power output. This feedback mechanism compensates for the instability introduced by long transmission lines, maintaining system stability while enabling distant photovoltaic transmission
4Reliability
If photovoltaic system provides frequency support, then power grid frequency stability improves, but device complexity increases due to control requirements
Solution Approach 1:
The inverter controller is designed to perform multiple functions: normal power conversion control and frequency support control. By integrating these functions into a single controller, the patent avoids adding separate complex control systems while enabling frequency support capability
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
The system effectively implements fast frequency support, enhancing the stability and security of the power grid by actively adjusting active power output in response to changes in power grid frequency, thereby preventing system instability and ensuring continuous operation.
Implementation Method 1
an output end of a photovoltaic module performs voltage conversion on the direct current
Implementation Method 2
a direct current converter, configured to connect an output of a photovoltaic module and perform voltage conversion on a direct current output by the photovoltaic module
Implementation Method 3
the inverter is configured to convert a direct current output by the direct current converter into an alternating current and output the alternating current to a power grid
Data Source
AI summary
A photovoltaic power generation system and a photovoltaic power generation system control method, to implement fast frequency support. The photovoltaic power generation system includes: a direct current converter, configured to connect an output of a photovoltaic module and perform voltage conversion on a direct current output by the photovoltaic module; an inverter, configured to convert a direct current output by the direct current converter into an alternating current and output the alternating current to a power grid; and a first controller, configured to generate a first drive signal based on two of a first voltage of the direct current of the direct current converter, an active power output by the inverter, and an operating parameter of the power grid, and control an operating state of the inverter based on the first drive signal.