Transformer AC-AC Converter Control for Fast Grid Frequency Response
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High penetration of non-synchronous generation (NSG) in power grids leads to challenges in frequency stability, voltage stability, short-circuit power levels, and harmonic stability, requiring rapid control of load to maintain grid frequency, which existing technologies like on-load tap changers cannot efficiently address due to their slow response time.
Innovation Solution
A method using a power electronics converter with a fractional rating connected to either side of a transformer, which measures and adjusts the output voltage based on grid frequency deviations to provide rapid demand response and frequency control, allowing for faster regulation of active power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If on-load tap changers are used to control output voltage, then voltage stability is maintained, but response time is slow and cannot address rapid frequency deviations
Solution Approach 1:
The patent replaces the mechanical on-load tap changer system with a power electronics converter system that uses electronic switching devices (such as IGBTs or IGCTs) to control output voltage. This electronic substitution eliminates the mechanical movement and contact wear inherent in tap changers, enabling response times in the order of milliseconds rather than seconds, thus resolving the contradiction between voltage stability and fast response time.
2Speed
If power electronics converters with full rating are used, then rapid frequency control is achieved, but device complexity and cost increase
Solution Approach 1:
The patent applies partial action by using a power electronics converter with a rating that is only a fraction (e.g., 10-30%) of the transformer's total power rating. The converter intervenes only when frequency deviations occur, providing rapid control during critical events while allowing the transformer to handle the bulk of power transmission. This partial intervention approach achieves fast frequency control without requiring a fully-rated converter, thus reducing device complexity and cost.
3Quantity of substance
If non-synchronous generation is integrated to increase renewable energy penetration, then clean energy production increases, but grid frequency stability deteriorates due to reduced rotating inertia
Solution Approach 1:
The patent implements a feedback control mechanism where the power electronics converter continuously monitors grid frequency and automatically adjusts its output to counteract frequency deviations. The converter measures the frequency error signal and modulates the transformer's output voltage accordingly, creating a closed-loop system that actively compensates for the lack of rotating inertia. This feedback control enables high renewable energy penetration while maintaining frequency stability through rapid electronic regulation.
Data Source
AI summary
A method for controlling an output voltage of at least one transformer in a power grid comprises providing the one transformer(s) with a power electronics converter and an output voltage controller, determining a grid frequency, comparing the grid frequency with a reference value, producing an error signal, applying the error signal as feedback to the controller, and generating a control action to cause the controller to change the output voltage of the transformer comprising a power electronics converter. The power electronics converter is an AC-AC converter, and the method comprises connecting the AC-AC converter to either a primary side or a secondary side of the transformer. The AC-AC converter has a first AC side and a second AC side and the method comprises connecting two terminals on the first AC side to a winding of the transformer, and connecting the second AC side to an external circuit line.