Transformer Protection Control Circuit for DC Blocking and Local Override
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Solution Overview
Problem
Existing power grid protection systems are inadequate in addressing repeated or severe geomagnetic disturbances and electromagnetic pulses, which can cause damage to transformers and disrupt grid stability, and they lack adequate control features to manage such events effectively while maintaining security against cyber threats.
Innovation Solution
A control circuit with a direct current blocking component and a switch assembly is connected in parallel, allowing for programmable operation modes to manage DC currents and voltages, including automatic switching based on detected events, and includes a method for remote operation with local override capabilities to prevent cyber vulnerabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitive circuit is used to block DC currents, then transformer protection is improved, but device complexity increases due to switching requirements
Solution Approach 1:
The protection system is divided into multiple functional components: a capacitive circuit for DC blocking, a switching assembly for mode transitions, and a control circuit for coordination. This segmentation allows each component to perform its specific function efficiently while maintaining overall system reliability.
Solution Approach 2:
The system pre-configures two operational modes (first mode with capacitive blocking, second mode with alternative protection) before any disturbance occurs. The control circuit can switch between these pre-prepared modes based on detected conditions, eliminating the need for complex real-time decision-making during actual disturbances.
2Ease of operation
If remote control capabilities are added to protection systems, then operability is improved, but security risks increase due to cyber threats
Solution Approach 1:
The control circuit acts as an intermediary between remote control interfaces and the critical protection functions. It receives remote commands but validates and filters them before execution, and can override remote commands if safety conditions are not met. This intermediary layer provides remote operability while maintaining security against cyber threats.
3Stability of the object's composition
If the switch assembly operates in normally-closed mode, then grid stability is improved, but vulnerability to DC currents increases during disturbance events
Solution Approach 1:
The switch assembly dynamically transitions between normally-closed and normally-open operational modes based on detected disturbance conditions. During normal operation, it remains closed to maintain grid stability. Upon detecting DC currents or harmonics exceeding thresholds, it automatically switches to normally-open mode to block harmful currents, thus adapting to changing conditions to maintain overall system stability.
Solution Approach 2:
The system applies preliminary anti-action by pre-configuring the ability to switch to normally-open mode that blocks DC currents. When disturbances are detected, the control circuit activates this pre-prepared protective state, preventing DC currents from causing half-cycle saturation and transformer damage before they can severely impact the system.
4Reliability
If protective measures are activated during geomagnetic disturbances, then transformer damage is prevented, but power loss increases due to bypass path removal
Solution Approach 1:
The system applies partial protection by selectively blocking only the harmful DC current components while allowing normal AC power flow to continue through alternative paths. The capacitive circuit blocks DC currents and harmonics but does not completely interrupt power flow, thus providing transformer protection while minimizing power loss during disturbance events.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces DC currents in AC power grids, enhances transformer protection, and provides remote control capabilities while maintaining local security, thereby improving grid stability and resilience against geomagnetic and electromagnetic events.
Implementation Method 1
a direct current blocking component electrically connected between a transformer neutral and a ground
Implementation Method 2
The triggering event is at least one of: a direct current or quasi-direct current between the transformer neutral and the ground, a direct current voltage at the transformer neutral, or a harmonic signal in at least one phase of the transformer
Data Source
AI summary
Methods and systems for controlling a circuit designed to protect electrical equipment, in particular sensitive power grid equipment such as transformers, are disclosed. In particular, methods of local and remote control of operation of protection circuits are provided that allow for remote access to change an operational mode of such protection circuits, while ensuring that power grid equipment is protected locally regardless of any configuration instructions received from a remote or centralized facility. Override levels may be set to ensure power grid transformer protection, regardless of operational mode or remote instruction.