Power Flow Control Device for Wind Farm Grid Stability
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Solution Overview
Problem
The increasing integration of converter-fed generating units like wind and photovoltaic installations into the electrical power supply grid poses challenges for stable operation, requiring complex and costly closed-loop control methods in each wind power installation, which can be impractical and expensive, especially when conventional transformers only manage voltage amplitude and not frequency.
Innovation Solution
A power flow unit with a DC link, electrical energy storage, and an inverter, capable of setting both voltage and frequency, acts as a virtual synchronous machine to connect the wind farm grid to the power supply grid, allowing for centralized control and reducing the need for individual wind farm installations to manage frequency, thereby simplifying the connection and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional transformers are used to connect wind farm grid to power supply grid, then voltage amplitude can be set, but frequency cannot be controlled and complex closed-loop control is required in each wind power installation
Solution Approach 1:
The patent introduces a power flow unit as an intermediary device between the wind farm grid and the power supply grid. This unit includes a converter and energy storage system that can centrally control both voltage and frequency, eliminating the need for complex individual control systems in each wind power installation while maintaining grid stability requirements.
2Reliability
If complex closed-loop control methods are implemented in each wind power installation, then grid stability requirements can be met, but implementation costs increase significantly
Solution Approach 1:
The patent merges the control functions of multiple wind power installations into a single centralized power flow unit. By combining the converter and energy storage system in one location, the system achieves grid stability control for the entire wind farm without requiring expensive individual control systems in each installation, thereby reducing overall implementation costs while maintaining reliability.
3Adaptability or versatility
If existing wind power installations are upgraded with modern control methods, then operational requirements can be fulfilled, but technical implementation becomes impractical
Solution Approach 1:
The power flow unit serves as an intermediary that enables existing wind power installations to meet modern operational requirements without requiring complex upgrades to each individual installation. The centralized converter and energy storage system handle all adaptive control functions, making the upgrade process practical and feasible for existing infrastructure.
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 solution enables stable operation of wind farms by emulating a synchronous generator, reducing the complexity and cost of implementing control methods, enhancing grid stability, and allowing for black start capabilities, while eliminating the need for reactive power control within individual wind installations and conventional transformers.
Implementation Method 1
The electrical energy store may be, for example, an electrical battery
Implementation Method 2
the power flow unit also has an inverter, which is connected to the DC link and is designed to inject at least the electrical power generated by the plurality of wind power installations into the electrical power supply grid
Implementation Method 3
the power flow unit further has a rectifier, which is connected to the electrical wind farm grid and to the DC link and is designed to conduct at least the electrical power generated by the plurality of wind power installations
Data Source
AI summary
A wind farm for supplying electrical power into a supply grid. The farm includes wind power installations, a farm grid connecting the installations, and a power flow control device. The power flow control device is configured to connect the farm grid and the supply grid such that an electrical power generated by the installations can be supplied into the supply grid. The power flow control device has at least: a DC link configured to conduct at least the electrical power generated by the installations, an electrical energy store connected to the DC link, an inverter connected to the DC link and configured to inject at least the electrical power generated by the installations into the supply grid, and a controller configured to drive the inverter in such a way that the farm, at the supply grid, in the steady state appears to be dynamic like an electromechanical synchronous machine.