AC Input Voltage Monitoring for Forsmark Effect Detection
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Solution Overview
Problem
Existing methods for monitoring the Forsmark effect in nuclear class electrical equipment are not timely, leading to potential damage from sudden changes in AC input power grid voltage, which can exceed the DC bus voltage's bearable range and affect inverter performance.
Innovation Solution
A method and device that calculate the change ratio of power grid voltage modulus values across multiple monitoring periods, using a sliding window approach to detect Forsmark effects by comparing current and previous periods, triggering protection when the change ratios exceed a set threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bus voltage of the DC bus is monitored to determine whether the Forsmark effect is generated, then the Forsmark effect can be detected, but the monitoring is not timely and cannot prevent device damage
Solution Approach 1:
The patent applies preliminary action by monitoring the AC input voltage before it is converted to DC bus voltage through the rectifier circuit. By detecting voltage changes at the AC input stage, the system can identify Forsmark effects earlier in the process, before they propagate to the DC bus and cause damage to sensitive components like IGBT tubes. This proactive monitoring approach enables timely protective actions.
Solution Approach 2:
The patent introduces an intermediary monitoring mechanism that observes the AC input voltage as an intermediate parameter before the final DC bus voltage is formed. By using the AC input voltage as an early indicator, the system creates a predictive monitoring layer that bridges the gap between external grid disturbances and internal device vulnerability, enabling earlier detection and response.
2Reliability
If the DC bus voltage is monitored, then the Forsmark effect can be detected, but the monitoring accuracy is insufficient to distinguish actual Forsmark effects from normal voltage fluctuations
Solution Approach 1:
The patent applies parameter changes by monitoring the rate of change of AC input voltage (dv/dt) rather than just absolute voltage levels. By detecting the speed and pattern of voltage changes, the system can distinguish between sudden Forsmark effects (characterized by rapid voltage changes) and normal gradual voltage fluctuations. This parameter-based differentiation significantly improves detection accuracy.
Solution Approach 2:
The patent implements feedback by continuously comparing the monitored AC input voltage changes against predetermined thresholds and patterns characteristic of Forsmark effects. When the voltage change rate exceeds the threshold, the system triggers protective feedback actions. This closed-loop approach with threshold-based feedback enables accurate discrimination between actual threats and normal variations.
Data Source
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AI summary
The present application provides a Forsmark effect monitoring method for a nuclear class electrical equipment, the method includes: acquiring a modulus value of a power grid voltage input to the nuclear class electrical equipment according to a preset monitoring period; matching a current monitoring period with a Yth monitoring period before the current monitoring period, and calculating a change ratio of the modulus value of the current monitoring period to the modulus value of a matched monitoring period; and when the change ratio corresponding to the current monitoring period and Y-1 change ratios corresponding to Y-1 monitoring periods before the current monitoring period are all greater than a change protection value, determining that the nuclear class electrical equipment will have the Forsmark effect. The present application can realize the timely detection of sudden changes in power grid voltage, so as to avoid the device damage caused by the Forsmark effect in the circuit of nuclear class electrical equipment, and ensure the normal operation of nuclear class electrical equipment.