Local Feed Unit Reactive Power Rate Limiting for Grid Voltage Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wind power installations face challenges in reducing power feed into the electrical supply grid quickly without causing undesirable voltage changes, particularly at transformers, due to the fast control response of existing systems, leading to yield losses and voltage spikes.
Innovation Solution
Implementing a method that limits the change in reactive power over time when adjusting real power feed, allowing for immediate reduction or increase of real power without preplanned ramps, and temporarily activating voltage control to dynamically correct voltage levels, thereby avoiding voltage spikes and maintaining stable grid operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the local feed unit reduces real power quickly using fast control response, then the control capability for the electrical supply grid is improved, but voltage spikes occur at the transformer due to rapid reactive power changes
Solution Approach 1:
The control unit limits the rate of change of reactive power before the actual power reduction occurs. By pre-establishing a maximum reactive power change rate (dQ/dt < max), the system prepares the reactive power level to change gradually, preventing voltage spikes that would occur with abrupt reactive power changes during fast real power reduction.
Solution Approach 2:
The system dynamically adjusts the reactive power output based on the rate of real power change. The control unit continuously monitors the real power reduction rate and correspondingly limits the reactive power change rate, creating a dynamic relationship where reactive power control adapts to the speed of real power changes to maintain voltage stability.
2Stability of the object's composition
If the local feed unit reduces power with preplanned ramps to avoid voltage changes, then voltage stability is improved, but yield losses increase due to early power reduction
Solution Approach 1:
The system changes the control parameter from a fixed preplanned ramp approach to a dynamic rate-limiting approach. Instead of reducing power early with a predetermined ramp, the control unit allows immediate real power reduction while dynamically adjusting the reactive power change rate parameter to prevent voltage instability, thereby eliminating unnecessary yield losses.
3Stability of the object's composition
If the variable ratio transformer adjusts the winding ratio to compensate for voltage changes, then voltage compensation is improved, but the transformer cannot respond fast enough to rapid voltage changes
Solution Approach 1:
The control unit pre-limits the reactive power change rate before voltage changes occur, preventing the need for fast transformer response. By controlling dQ/dt in advance, the system avoids rapid voltage fluctuations that would require the variable ratio transformer to respond quickly, allowing the transformer to operate within its slower mechanical adjustment capabilities.
Data Source
AI summary
A method for feeding electric power into an electrical supply grid by means of a local feed unit. The feed unit is connected to a grid link point connected to a transformer point directly or via a supply connection. The transformer point is connected to a grid section via a transformer. The method includes feeding electrical real power into the electrical supply grid at the grid link point, feeding electrical reactive power into the electrical supply grid at the grid link point, detecting a change to be made in the real power to be fed in, and changing the fed-in real power in accordance with the detected change to be made. The method includes limiting a change in the fed-in reactive power over time when changing the fed-in real power and/or immediately thereafter or temporarily activating voltage control on the basis of the change in the fed-in real power.