Wind Farm Control for Low Short-Circuit Current Stability
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Solution Overview
Problem
Wind farms connected to the grid face stability issues due to low short-circuit current ratios, leading to potential voltage and angle stability problems, which can result in grid instability and even shutdowns, as seen in past events like in the USA and Italy, where existing solutions fail to maintain stability with SCR < 4, limiting power output and requiring grid expansion.
Innovation Solution
A method for controlling wind farms using voltage-controlled inverters to manage active and reactive power feed into the grid, with a central control unit adjusting target values for individual wind turbines to maintain stability, allowing operation with SCR > 1.5, by continuously monitoring and adapting to grid conditions, preventing voltage regulation instabilities and loss of stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If wind farms are connected to the grid with low short-circuit current ratios (SCR < 4), then power output can be increased, but voltage and angle stability problems occur leading to grid instability
Solution Approach 1:
The patent changes the control parameters of wind turbines by implementing a centralized control system that adjusts active and reactive power setpoints based on grid conditions. The control system modifies operating parameters such as power factor, voltage regulation settings, and power output levels to maintain stability when SCR is low, thereby resolving the contradiction between high power output and grid stability
Solution Approach 2:
The patent implements a feedback mechanism where the centralized control system continuously monitors grid voltage, frequency, and power flow, then adjusts wind turbine operating parameters in response. This closed-loop control allows the system to detect stability issues and correct them by modifying power output and reactive power compensation, enabling stable operation at low SCR values while maintaining high power output
2Reliability
If existing control solutions are used to manage power feed-in, then some grid support is provided, but they fail to maintain stability with SCR < 4 and limit power output
Solution Approach 1:
The patent creates a universal control system that performs multiple functions: active power control, reactive power compensation, voltage regulation, and stability monitoring. This multi-functional centralized control system can operate effectively across a wide range of SCR values, providing both stability maintenance and high power output capability that single-function existing solutions cannot achieve
Solution Approach 2:
The patent implements dynamic control where the system continuously adapts its operating characteristics based on real-time grid conditions. The control system adjusts power output limits, reactive power compensation levels, and voltage regulation parameters dynamically, allowing the wind farm to maintain stability while maximizing power output under varying grid conditions, unlike static existing solutions
Data Source
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AI summary
Method for controlling a wind farm (200) comprising several wind turbines (202) for feeding electrical power into an AC electrical network (206) at a grid connection point (PCC) (204), comprising the steps of: injecting a three-phase current at the PCC (204), detecting a grid voltage (UN) at the PCC, comparing the PCC detected at the PCC (204) with at least one predetermined setpoint, determining setpoints for the wind turbines (202) depending on the comparison performed to comply with a stability criterion at the PCC (204), transmitting the determined setpoints to plant control units (212) of the individual wind turbines (202), and generating electrical current at each of the wind turbines (202) depending on the predetermined setpoints for joint injection at the PCC (204).where network sensitivities are recorded and stored through a previously performed network analysis, and current network sensitivities are recorded at a current operating point, and control is carried out depending on a comparison of the current network sensitivities with the previously recorded network sensitivities.