Electrolysis Grid Flicker Assessment Using a Fictitious Grid Model
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Solution Overview
Problem
Existing methods for flicker assessment of large electrolysis systems connected to power grids, such as those using the IEC 61000-4-15 standard, fail to accurately determine individual contributions to overall flicker at the point of common coupling (PCC) due to limitations in distinguishing between multiple electrolysis systems, making it impossible to assess flicker before new installations, which contradicts transmission system operator requirements.
Innovation Solution
A method involving a simulation-based approach using a fictitious grid circuit to measure and simulate voltage and current time-series values, applying them to a flickermeter to determine short-term flicker emissions, and normalizing these values with flicker coefficients and factors to characterize flicker independently of the connected network, allowing for pre-connection assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If IEC 61000-4-15 standard is used for flicker assessment at PCC, then flicker measurement can be performed, but individual contributions of each electrolysis system cannot be distinguished
Solution Approach 1:
The patent divides the overall flicker assessment into individual system contributions by introducing system-specific identification mechanisms. Each electrolysis system is assigned unique parameters (e.g., system ID, operating characteristics) that allow their individual flicker signatures to be segmented and distinguished from the aggregate PCC measurement, enabling separate evaluation of each system's contribution.
Solution Approach 2:
The patent introduces an intermediary assessment layer between the PCC measurement and individual system evaluation. This intermediary mechanism uses measured PCC voltage fluctuations combined with system-specific operating data to calculate and attribute flicker contributions to individual electrolysis systems, acting as a mediator that translates aggregate measurements into system-specific assessments.
2Measurement precision
If actual voltage measurements at PCC are required during operation, then flicker assessment can be performed, but assessment cannot be done before new installations are connected
Solution Approach 1:
The patent enables preliminary flicker assessment by allowing calculations to be performed using system parameters and simulated or projected operating conditions before actual connection. The assessment methodology is designed to accept input parameters that can be estimated or specified in advance, enabling pre-connection evaluation without requiring the system to be physically connected and operating.
Solution Approach 2:
The patent creates a virtual representation or model of the electrolysis system's electrical characteristics and operating behavior. This copy or simulation model allows flicker assessment to be performed on projected performance based on system specifications and typical operating conditions, eliminating the need for actual physical operation and connection to conduct the assessment.
3Power
If multiple electrolysis systems are connected to common PCC, then overall plant capacity increases, but recalculation of flicker severity for all systems becomes impossible or very complicated
Solution Approach 1:
The patent segments the flicker assessment process into independent system-level evaluations rather than requiring aggregate recalculation. Each electrolysis system's flicker contribution is assessed separately using its own operating parameters and characteristics, allowing individual system evaluation without complex interactions between multiple systems at the PCC level.
Solution Approach 2:
The patent enables each electrolysis system to perform its own flicker assessment using its internal operating data and parameters. The assessment methodology is designed to be self-contained at the system level, where each system can independently evaluate its flicker contribution based on its own voltage and current measurements, eliminating the need for centralized recalculation involving all systems.
Data Source
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AI summary
A method (100) of flicker assessment for an electrolysis system, wherein the electrolysis system is connected to an AC power grid via a point-of-connection, comprises operating the electrolysis system in a continuous operation mode (104) and in a switching operation mode (105) and measuring (106, 107), at the point-of-connection, voltage time-series values and current time-series values; determining (108, 109) simulated instantaneous voltage time-series values from a fictitious grid circuit that comprises an ideal phase-to-neutral voltage source, a fictitious grid impedance and a current sink representing the electrolysis system, wherein said measured voltage time-series values and current time-series values correspond to input currents and input voltages of the current sink; and applying (110, 111) said simulated instantaneous voltage time-series values to a flickermeter for determining at least corresponding short-term flicker emission values from each simulated instantaneous voltage time-series.