Control system for transformer protection system
AssigneeTechHold, LLC
InventorsDavid Anderson, Greg Fuchs
Life of this patent
Estimating the term…
Abstract
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.
Claims34
A control circuit communicatively connected to a transformer protection circuit including a direct current blocking component electrically connected between a transformer neutral and a ground and a switch assembly electrically connected in parallel to the direct current blocking component, the control circuit comprising:
- a programmable circuit configured to execute instructions which cause the control circuit to adjust a default setting for operation of the transformer protection circuit between a first mode and a second mode;
- wherein, in the first mode, a switch assembly of the transformer protection circuit operates in a normally-closed state and the programmable circuit automatically opens the switch assembly to remove a bypass path from between the transformer neutral and the ground based on detection of a triggering event, the bypass path bypassing the direct current blocking component, the triggering event being at least one of:
- a direct current or quasi-direct current between the transformer neutral and the ground;
- a direct current or quasi-direct current in at least one phase of the transformer;
- a direct current voltage at the transformer neutral;
- a harmonic signal in at least one phase of the transformer;
- or
- an electromagnetic event detected in a vicinity of the transformer;
- and
- wherein, in the second mode, the switch assembly operates in a normally-open state and the programmable circuit automatically closes the switch assembly to form the bypass path between the transformer neutral and the ground based on detection of a second triggering event, the second triggering event being at least one of:
- an alternating current at the transformer neutral above a predetermined AC threshold;
- an alternating current between the transformer neutral and the ground exceeding a second predetermined AC threshold over a predetermined amount of time;
- a voltage at the transformer neutral above a predetermined threshold;
- a time-overvoltage at the transformer neutral exceeding a second predetermined threshold;
- or
- actuation of an overvoltage protection device positioned in parallel with the direct current blocking component between the transformer neutral and the ground.
A control circuit communicatively connected to a transformer protection circuit including a direct current blocking component electrically connected between a transformer neutral and a ground and a switch assembly electrically connected in parallel to the direct current blocking component, the control circuit comprising:
- a programmable circuit configured to execute instructions to:
- detect a triggering event at the transformer neutral;
- based on the triggering event occurring, determine whether to automatically actuate the switch assembly to close to form a bypass path between the transformer neutral and the ground;
- based on a hazard condition being present when the triggering event is detected, override the determination of whether to actuate the switch assembly, thereby maintaining the switch assembly in an open position;
- wherein the triggering event comprises at least one of:
- a voltage at the transformer neutral above a predetermined threshold;
- a time-overvoltage at the transformer neutral exceeding a second predetermined threshold;
- actuation of an overvoltage protection device positioned in parallel with the direct current blocking component between the transformer neutral and the ground;
- an alternating current between the transformer neutral and the ground above a predetermined AC threshold;
- or
- an alternating current at the transformer neutral exceeding a second predetermined AC threshold over a predetermined amount of time;
- wherein the hazard condition comprises at least one of:
- a direct current (DC) voltage at the transformer neutral exceeding a predetermined DC voltage threshold;
- an electromagnetic pulse event;
- or
- a geomagnetically induced current having a rise time of less than 25 seconds.
A method of operating a transformer protection circuit, the method comprising:
- monitoring a voltage at a transformer neutral of a transformer positioned within the power grid, the transformer neutral being electrically connected to a direct current blocking component that electrically connects the transformer neutral to a ground;
- based on a direct current voltage at the transformer neutral being below a predetermined threshold, determining whether an electrical condition exists to actuate a switch assembly to close to form a bypass path between the transformer neutral and the ground, the switch assembly being operable in a first mode or a second mode;
- and
- based on the direct current voltage at the transformer neutral being above the predetermined threshold, overriding the determination of whether to actuate the switch assembly, thereby maintaining the switch assembly in an open position and eliminating the bypass path regardless of whether the switch assembly is operating in the first mode or the second mode;
- wherein, in the first mode, the switch assembly operates in a normally-closed state and opens to remove a bypass path from between the transformer neutral and the ground based on detection of a triggering event, the bypass path bypassing the direct current blocking component;
- and
- wherein, in the second mode, the switch assembly operates in a normally-open state and closes to form the bypass path between the transformer neutral and the ground based on detection of a second triggering event.
A control circuit communicatively connected to a transformer protection circuit including a direct current blocking component electrically connected between a transformer neutral and a ground and a switch assembly electrically connected in parallel to the direct current blocking component, the control circuit comprising:
- a programmable circuit;
- a memory storing instructions executable by the programmable circuit, the instructions causing the control circuit to perform a method comprising:
- initiating operation of the control circuit in a selected mode, the selected mode being operator-selectable from between an automatic mode and a manual mode;
- in the automatic mode:
- operating to automatically actuate the switch assembly from an open position to a closed position in response to one or more grounding conditions using grounding code to establish a solid metallic path from a transformer neutral to ground;
- operating to automatically actuate the switch assembly from the closed position to the open position in response to one or more blocking conditions using blocking code to disconnect the solid metallic path between the transformer neutral and ground;
- in the manual mode:
- operating to maintain the switch assembly in a closed position using manual closed code, thereby maintaining the solid metallic path between the transformer neutral and the ground regardless of presence of the one or more blocking conditions;
- and
- operating to maintain the switch assembly in an open position using manual open code, thereby maintaining disconnection of the solid metallic path between the transformer neutral and the ground regardless of presence of the one or more grounding conditions.
Dependencies are inferred from the claim text.