Transformer Neutral Protection Circuit for AC/DC Fault Interruption
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing transformer protection systems face challenges in effectively managing high voltage and current induced by solar storms and HEMP events, which can cause damage due to the inability to break both AC and DC currents without relying on zero-crossings.
Innovation Solution
A transformer protection system utilizing a single switching element capable of breaking both AC and DC currents, a DC blocking component, and an overvoltage protection device, with a control system to detect electrical events and actuate the switching element accordingly, without relying on zero-crossings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single DC switch is used to break both AC and DC currents, then the device complexity is reduced, but the reliability decreases because DC switches are not designed or rated to break AC current at power grid voltage and current levels
Solution Approach 1:
The patent applies multi-functionality by enabling a single DC switching element to perform both AC current breaking and DC current breaking functions. The DC switch is designed with enhanced capabilities to handle both types of currents, eliminating the need for separate AC and DC switches while maintaining protection reliability through proper rating and design considerations.
Solution Approach 2:
The patent merges the functions of separate AC and DC switching elements into a single DC switch. By combining these functions, the circuit complexity is reduced while the switch is designed to accommodate both AC and DC breaking requirements through appropriate voltage and current ratings, arc suppression mechanisms, and contact design.
2Strength
If an AC switch is used to break AC current, then the voltage withstand rating is improved, but the ability to break DC current deteriorates because AC switches rely on current zero crossings which do not exist in DC current
Solution Approach 1:
The patent applies parameter changes by modifying the switching element's characteristics to handle both AC and DC currents. The DC switch is designed with specific parameters including higher voltage ratings, enhanced arc suppression capabilities, and contact designs that can interrupt DC current without relying on zero crossings, while still maintaining the ability to break AC current effectively.
3Object-generated harmful factors
If a DC switch is used to break DC current, then the DC current breaking ability is improved, but the voltage withstand rating deteriorates because DC switches have lower voltage ratings compared to AC switches
Solution Approach 1:
The patent applies parameter changes by selecting and designing a DC switch with enhanced voltage rating parameters. The switch is specified with voltage and current ratings that exceed the maximum expected conditions at the transformer neutral, ensuring both adequate DC current breaking capability and sufficient voltage withstand rating for power grid applications.
4Reliability
If the transformer neutral is connected to ground, then the protection against induced DC current is improved, but the damage from high current passing to ground worsens during solar storms and HEMP events
Solution Approach 1:
The patent applies dynamics by implementing a controllable switching element that can dynamically change the grounding state of the transformer neutral. The DC switch can be opened to isolate the neutral from ground during solar storms and HEMP events, preventing high current damage, and closed under normal conditions to provide DC current protection, thereby adaptively responding to different operational conditions.
Solution Approach 2:
The patent applies preliminary action by proactively opening the DC switch before high current damage can occur during solar storms and HEMP events. The control system detects the onset of these events and actuates the switch to open, preventing the harmful high current from passing to ground before damage can occur.
Data Source
AI summary
Circuits and methods of protection of an electrical power distribution system components, such as a power grid transformer, are disclosed. In example aspects, a transformer protection system may include a single switch electrically connected between a transformer neutral and ground that does not rely on zero crossing signals for actuation. In some further example aspects, the transformer protection system may include an overvoltage protection device electrically connected in parallel with a switch assembly and a DC blocking component between a transformer neutral and ground. In such arrangements, a sensor may be included within the transformer protection system to detect current through the overvoltage protection device, for example to detect activation of the overvoltage protection device.