Thyristor-Controlled Terminal Capacitor for Wind Fault Stability
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Solution Overview
Problem
Wind generator systems face transient stability issues during network faults due to reactive power demand, typically requiring auxiliary devices like SVC or STATCOM at the grid side, which increases costs and complexity.
Innovation Solution
A power electronic control-based capacitor at the wind generator terminal, utilizing back-to-back thyristor switching devices, controls reactive power by varying the firing angle of thyristors from 0 to 180 degrees, eliminating the need for auxiliary devices like SVC or STATCOM by functioning effectively at both steady and transient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If auxiliary devices like SVC or STATCOM are used at the grid side to maintain wind generator stability during faults, then transient stability is improved, but device complexity and cost increase
Solution Approach 1:
The invention merges the functions of the fixed capacitor and auxiliary compensators (SVC/STATCOM) into a single controlled capacitor unit. The thyristor-controlled capacitor can operate in both capacitive and inductive modes, eliminating the need for separate auxiliary devices while maintaining transient stability during faults.
Solution Approach 2:
The controlled capacitor serves multiple functions: it provides reactive power compensation during steady state operation and acts as a dynamic compensator during transient fault conditions. This multi-functionality replaces the need for dedicated auxiliary stability devices.
2Reliability
If auxiliary devices like SVC or STATCOM are used at the grid side to maintain wind generator stability during faults, then transient stability is improved, but cost increases
Solution Approach 1:
The invention merges the functions of the fixed capacitor and auxiliary compensators (SVC/STATCOM) into a single controlled capacitor unit. The thyristor-controlled capacitor can operate in both capacitive and inductive modes, eliminating the need for separate auxiliary devices while maintaining transient stability during faults.
Solution Approach 2:
The controlled capacitor serves multiple functions: it provides reactive power compensation during steady state operation and acts as a dynamic compensator during transient fault conditions. This multi-functionality replaces the need for dedicated auxiliary stability devices.
3Ease of operation
If a fixed capacitor is used at the wind generator terminal for reactive power compensation, then steady state operation is maintained, but transient stability during faults deteriorates
Solution Approach 1:
The invention transforms the static fixed capacitor into a dynamic controlled capacitor by introducing thyristor switching devices. The firing angle control allows the capacitor to dynamically adjust its reactive power output, providing high reactive power during faults (firing angle near 0 degrees) and normal operation during steady state (firing angle near 180 degrees).
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 maintains wind generator stability during faults without auxiliary devices, reducing costs and simplifying the system by using only a single reactive power compensator, the fixed capacitor, and eliminating the need for additional components like step-down transformers and voltage source converters.
Implementation Method 1
The invention comprises a power electronic control-based capacitor ("C") to be used at the terminal of a grid-connected wind generator system... The wind generator terminal capacitor is controlled through power electronics... The function of the capacitor depends on the triggering or firing-angle of the thyristor switches
Data Source
AI summary
A power electronic control-based capacitor to be used at the terminal of a grid-connected wind generator system for improving the transient stability of the generator following a fault in the network. This eliminates the need of adding auxiliary control devices at the grid side. The wind generator terminal capacitor is controlled through power electronics in such a way as to function both at the steady state and transient conditions maintaining the stability of the wind generator. A power electronic control-based terminal capacitor (“C”) is connected through two back-to-back thyristor switching devices, T1 and T2. The function of the capacitor depends on the triggering or firing-angle of the thyristor switches, which varies from 0 degrees to 180 degrees.