Wind Turbine Negative Sequence Regulation for Grid Stability
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Solution Overview
Problem
Wind energy installations face challenges in managing unbalanced grid faults, leading to torque oscillations and increased risk of failure, as existing negative phase sequence system regulation mechanisms either fail to adequately address unbalances or introduce additional voltage unbalances, requiring synchronous generators for stability.
Innovation Solution
Implementing a phase-specific negative phase sequence system regulation that separates active and reactive components, allowing for optimal utilization of current in wind energy installations to stabilize the grid during unbalanced conditions, reducing the need for synchronous generators and minimizing mechanical loadings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a negative phase sequence system regulation mechanism is implemented to counteract torque oscillations caused by unbalanced grid faults, then torque oscillations are reduced, but larger voltage unbalances occur in the grid
Solution Approach 1:
The patent segments the negative phase sequence current into active and reactive components using a phase control module. The active component is used to counteract torque oscillations while the reactive component is regulated to minimize voltage unbalance. This segmentation allows independent control of each component's effect on the grid.
Solution Approach 2:
The patent changes the parameter control strategy by regulating the reactive component of the negative phase sequence current to a desired value (preferably zero) while allowing the active component to counteract torque oscillations. This parameter separation and independent regulation resolves the contradiction between torque stabilization and voltage balance.
2Reliability
If synchronous generators are provided in the grid to maintain stability during unbalanced faults, then grid stability is improved, but additional outlay is required
Solution Approach 1:
The patent enables wind energy installations to provide their own grid stabilization service through the negative phase sequence system regulation mechanism. The phase control module allows the converter to independently regulate active and reactive components of negative sequence current, eliminating the need for additional synchronous generators and reducing system complexity.
Solution Approach 2:
The patent makes the wind energy installation's converter multi-functional by enabling it to simultaneously perform power conversion and grid stabilization functions. The negative phase sequence regulation mechanism allows the converter to counteract torque oscillations and maintain grid stability without requiring dedicated synchronous generators.
3Power
If current is increased to provide reactive power for grid support, then reactive power capability is improved, but current-carrying components may be overloaded
Solution Approach 1:
The patent segments the current capability into positive phase sequence and negative phase sequence components, and further segments the negative sequence into active and reactive components. This allows the controller to optimize current distribution: using positive sequence for active power and selectively using negative sequence reactive component for grid support without exceeding thermal limits.
Solution Approach 2:
The patent applies partial action by regulating the reactive component of negative phase sequence current to a desired value rather than maximum available current. This provides sufficient reactive power for grid stabilization while maintaining safety margins and preventing overload of current-carrying components.
Data Source
AI summary
A wind energy installation can include a generator which is driven by a rotor and generates electrical power in a multiphase manner for feeding into a network, a converter which is connected to the generator and to the network, and a control system which interacts with the converter and includes a negative sequence system regulation mechanism. The negative sequence system regulation mechanism can include a phase control module configured to determine an electrical variable of the negative sequence system according to the phase. Accordingly, an available current can be provided according to the operating situation for active power or idle power in the negative sequence system regulation mechanism. The negative sequence system regulation mechanism can thus help stabilize the network in the event of asymmetrical network conditions. Also, this relates to a correspondingly equipped wind park and an operating method.