An example method may include generating an alternating current (AC) output at a power source within a borehole in a subterranean formation. An electrical component may receive a direct current (DC) output from a converter circuit coupled to the power source and the electrical component. One or more measurements corresponding to the power source, the converter circuit, the electrical component, or a protection circuit coupled to the converter circuit may be received. Blocking devices within the protection circuit may be selectively caused to block current flow in the converter circuit based, at least in part, on the one or more received measurements.

An example method may include generating an alternating current (AC) output at a power source within a borehole in a subterranean formation. An electrical component may receive a direct current (DC) output from a converter circuit coupled to the power source and the electrical component. One or more measurements corresponding to the power source, the converter circuit, the electrical component, or a protection circuit coupled to the converter circuit may be received. Blocking devices within the protection circuit may be selectively caused to block current flow in the converter circuit based, at least in part, on the one or more received measurements.

A power conversion apparatus having a converter, an inverter controlled by inverter controller, and an input power source fluctuation detecting and controlling circuit is proposed. The input power source fluctuation detecting and controlling circuit includes an input power source fluctuation detector and a converter failure detector to detect overcurrent and/or overvoltage of the converter. When both of the input power source fluctuation and the converter failure are detected, the converter is gate blocked, and the inverter continues its operation, and when the DC voltage become lower than a threshold voltage during the converter is gate blocking, the input power source fluctuation detecting and controlling circuit outputs an inverter control changeover flag to the inverter controller for switching a contents of inverter control.

The respective proportionality constants of magnetic force by magnetic field producing portion for biasing the plug in the direction of insertion and resilient force by a spring mechanism for biasing the plug in the direction of extraction are adjusted in such a manner that the resilient force is greater than the magnetic force until the plug pin reaches an intermediate insertion position at which the plug pin comes into proximity to or separates from the socket contact, whereas the magnetic force is greater than the resilient force at a position at which the plug pin is inserted into a complete insertion position for a hot-line connection to the socket contact. The plug pin in the vicinity of the intermediate insertion position, at which there is a possibility of occurrence of an arc discharge, is ejected by the resilient force.

The respective proportionality constants of magnetic force by magnetic field producing portion for biasing the plug in the direction of insertion and resilient force by a spring mechanism for biasing the plug in the direction of extraction are adjusted in such a manner that the resilient force is greater than the magnetic force until the plug pin reaches an intermediate insertion position at which the plug pin comes into proximity to or separates from the socket contact, whereas the magnetic force is greater than the resilient force at a position at which the plug pin is inserted into a complete insertion position for a hot-line connection to the socket contact. The plug pin in the vicinity of the intermediate insertion position, at which there is a possibility of occurrence of an arc discharge, is ejected by the resilient force.

An example method may include generating an alternating current (AC) output at a power source within a borehole in a subterranean formation. An electrical component may receive a direct current (DC) output from a converter circuit coupled to the power source and the electrical component. One or more measurements corresponding to the power source, the converter circuit, the electrical component, or a protection circuit coupled to the converter circuit may be received. Blocking devices within the protection circuit may be selectively caused to block current flow in the converter circuit based, at least in part, on the one or more received measurements.

A power conversion apparatus having a converter, an inverter controlled by inverter controller, and an input power source fluctuation detecting and controlling circuit is proposed. The input power source fluctuation detecting and controlling circuit includes an input power source fluctuation detector and a converter failure detector to detect overcurrent and/or overvoltage of the converter. When both of the input power source fluctuation and the converter failure are detected, the converter is gate blocked, and the inverter continues its operation, and when the DC voltage become lower than a threshold voltage during the converter is gate blocking, the input power source fluctuation detecting and controlling circuit outputs an inverter control changeover flag to the inverter controller for switching a contents of inverter control.

The respective proportionality constants of magnetic force by magnetic field producing portion for biasing the plug in the direction of insertion and resilient force by a spring mechanism for biasing the plug in the direction of extraction are adjusted in such a manner that the resilient force is greater than the magnetic force until the plug pin reaches an intermediate insertion position at which the plug pin comes into proximity to or separates from the socket contact, whereas the magnetic force is greater than the resilient force at a position at which the plug pin is inserted into a complete insertion position for a hot-line connection to the socket contact. The plug pin in the vicinity of the intermediate insertion position, at which there is a possibility of occurrence of an arc discharge, is ejected by the resilient force.

The respective proportionality constants of magnetic force by magnetic field producing portion for biasing the plug in the direction of insertion and resilient force by a spring mechanism for biasing the plug in the direction of extraction are adjusted in such a manner that the resilient force is greater than the magnetic force until the plug pin reaches an intermediate insertion position at which the plug pin comes into proximity to or separates from the socket contact, whereas the magnetic force is greater than the resilient force at a position at which the plug pin is inserted into a complete insertion position for a hot-line connection to the socket contact. The plug pin in the vicinity of the intermediate insertion position, at which there is a possibility of occurrence of an arc discharge, is ejected by the resilient force.

The present invention discloses a direct-current power transmission protection device, including a resistor unit and a bidirectional circulation current switch unit, and the resistor unit and the bidirectional circulation current switch unit being connected in parallel to form the protection device, where at least one resistor is cascaded to form the resistor unit, and at least one bidirectional circulation current switch is cascaded to form the bidirectional circulation current switch unit. In addition, the present invention also provides a converter including the protection device, and at least one protection device is connected in series in each phase unit. The present invention provides the protection device, the converter and a protection method for flexible direct-current power transmission, which can rapidly and effectively suppress direct-current short circuit current and damp current oscillation, and not only can better protect equipment safety, but also can greatly shorten fault current attenuation time, thus shortening direct-current shutdown time and further decreasing economic loss and system destabilization risk caused by shutdown to the max. Moreover, the protection device is structurally simple and low in cost, and has good implementability and economic efficiency.