Grid Stability Measurement Using Synchronized Current Impulses
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Solution Overview
Problem
Modern alternating current (a.c.) power grids face instability due to interactions between inverter control loops and load feedback mechanisms, making it difficult to measure stability without disrupting sensitive loads, and existing methods either cause significant voltage variations or require impractical control over generators.
Innovation Solution
A 'thumper' device is used to apply synchronized current impulses to the grid, allowing for precise measurement of stability without disrupting sensitive loads by distinguishing voltage effects from background variations, using a voltage measurement device capable of high resolution and synchronization with absolute time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional impulse stimulation methods are used to measure grid stability, then measurement capability is achieved, but sensitive loads are disrupted due to significant voltage variations
Solution Approach 1:
The patent applies partial action by using a series of small-magnitude current impulses rather than a single large impulse. Each impulse is sufficiently small to avoid disrupting sensitive loads, but the cumulative effect of multiple impulses provides sufficient signal strength for measurement. The measurement system integrates responses from multiple impulses to achieve the necessary measurement precision without exceeding voltage thresholds that would harm sensitive equipment.
2Object-affected harmful factors
If small current impulses are used to avoid disrupting loads, then sensitive loads are protected, but the voltage effects become difficult to distinguish from background variations
Solution Approach 1:
The patent employs feedback mechanisms in two forms: first, the grid's own feedback loops (inverter control loops and load feedback mechanisms) create the stability characteristics being measured; second, the measurement system uses feedback by comparing expected voltage responses with actual measurements to distinguish impulse effects from background variations. The system continuously monitors and adjusts measurements based on observed grid behavior, enabling accurate detection of small voltage effects even in the presence of background noise.
Solution Approach 2:
The patent uses periodic action by applying a series of regularly spaced current impulses to the grid. This periodic stimulation creates a consistent measurement pattern that allows the measurement system to distinguish impulse-induced voltage effects from random background variations through correlation and averaging techniques. The periodic nature of the impulses provides a reference signal that enhances the detectability of small voltage changes while maintaining protection for sensitive loads.
3Stability of the object's composition
If limits are placed on inverter-supplied power to avoid instabilities, then grid stability is maintained, but deployment of useful technologies is restricted
Solution Approach 1:
The patent replaces mechanical/conventional measurement methods with an electronic measurement system that uses synchronized current impulses and high-precision voltage detection. This substitution enables accurate stability measurement without requiring physical modifications to the grid or limitations on inverter power. The electronic measurement approach provides the data needed to safely expand inverter deployment while maintaining grid stability through informed control strategies.
Data Source
AI summary
A system measures the stability of a live a.c. power distribution grid, without disrupting sensitive loads on that grid. The system applies repetitive time-synchronized loads to create current pulses, and resulting voltage instabilities, on the grid. The current pulses are sized to ensure that the resulting voltage instabilities are too small to affect the sensitive loads. Time-synchronized voltage measurement devices record the voltage instabilities. The time synchronization, and the repetitive nature of the current pulses, allow the voltage instabilities caused by the current pulses to be extracted from the larger background voltage variations.