A system and method for maintaining electrical stability of a high-voltage transmission power system in response to a fault. The method includes detecting the fault, opening a switch to clear the fault, performing a first pulse test for a predetermined duration of time to determine if the fault is still present, preventing a reclosing operation from occurring if the pulse test indicates that the fault is still present, and allowing the reclosing operation to occur if the first pulse test indicates that the fault is not present. One or more subsequent pulse tests can be performed if the first pulse test is inclusive about the persistence of the fault, where the reclosing operation is prevented from occurring if the pulse tests indicate that the fault is still present and the reclosing operation is allowed if the pulse tests indicate that the fault is no longer present.

Gate control of power semiconductor devices using reduced gate drivers is disclosed. A circuit breaker may include a multitude of transistors, such as insulated gate bipolar transistors (IGBTs), connected in series with one another. Each transistor may be connected to a respective gate resistor. Diodes may be connected between various gate resistors. One or more resistor-capacitor (RC) snubber circuits may be provided in parallel with one or more of the transistors. Likewise, one or more metal-oxide varistors (MOVs) may be connected in parallel to one or more of the transistors. A gate driver (e.g., a single gate drive) may be connected to the one or more diodes and an emitter of at least one of transistors.

A method for controlled switching of a circuit breaker is described. The method includes initiating operation of the circuit breaker at an initiation time derivable from an initiation time function by calculating a value of the initiation time function with respect to a command instant. The initiation time function is a sum of the command instant and a command delay time. The initiation time function depends on a first parameter and a second parameter. At least one of: the partial derivative of the initiation time function with respect to the first parameter is dependent on the second parameter or the partial derivative of the initiation time function with respect to the second parameter is dependent on the first parameter. Further, a system for controlled switching according to the method and a circuit breaker including the system are described.

An electrical unit may include a current controller including an electrical regulator, a control circuit connected to a first input of the electrical regulator, a timer connected to a second input of the electrical regulator, and/or a turn-off circuit including a turn-off switch. The current controller may be configured to provide a first output signal in a first mode and a second output signal in a second mode. The current controller may be configured to transition from the first mode to the second mode based on a timer output of the timer. An electrical system may include an electrical unit and or a switch connected to the electrical unit. The switch may include a coil. The electrical unit may be configured to provide the first output signal to the coil in the first mode and provide the second output signal to the coil in the second mode.

A direct current circuit breaker, including: n in number circuit breaker modules connected in series, one energy-absorbing and voltage-limiting module connected in parallel to the n in number circuit breaker modules, and a trigger module. The n in number circuit breaker modules each includes a mechanical switch and a commutation branch circuit which are connected in parallel; each commutation branch circuit includes a charging commutation module and a commutation capacitor which are connected in series; the charging commutation module is configured to charge up the commutation capacitor and produce reverse current to cut off the mechanical switch; the one energy-absorbing and voltage-limiting module is configured to absorb energy stored in inductive elements of power systems after a fault current is cut off, so as to limit voltage and protect the mechanical switch, and n is a positive integer greater than or equal to 1.

A method for determining an operational status of a switching device for switching an electrical unit including a first circuit and a second circuit, each circuit respectively including: a vacuum breaker including a fixed electrode and a mobile electrode; and a control device connected to the mobile electrode via an elastic device. The method including: for each of the first and second circuits, determining a transition instant at which the mobile electrode comes into contact with the fixed electrode; determining a difference between the transition instant of the first vacuum breaker and the transition instant of the second vacuum breaker; determining that the operational status is a first status known as “nominal synchronization” if the difference is less than a threshold; and determining that the operational status is a second status known as “abnormal synchronization” if the difference is greater than the threshold.

This application discloses a photovoltaic direct-current breaking apparatus, including a positive connection terminal and a negative connection terminal for connecting a photovoltaic string and a photovoltaic energy converter, a first diode, a first switch, a convector circuit, and an energy absorption circuit, where the first switch, the convector circuit, and the energy absorption circuit are connected in parallel. The convector circuit can effectively avoid arc discharge and ablation generated when the first switch cuts off a direct-current circuit between the photovoltaic string and the photovoltaic energy converter. The first diode can effectively bypass energy stored by an energy storage device in the photovoltaic energy converter, helping reduce required specifications of a semiconductor device in the convector circuit. The energy absorption circuit can also effectively reduce required specifications of the semiconductor device and a varistor.

A pulse voltage conditioning method of a vacuum interrupter with automatic conditioning energy adjustment based on a trend of a breakdown voltage of the vacuum interrupter during a conditioning process. A current-limiting resistor and a parallel capacitor are automatically adjusted to ensure the conditioning energy reaching a critical value without deconditioning effect. The critical value refers to a maximum conditioning energy without damaging the electrode surfaces, namely an optimal conditioning energy, which can better remove insulation defects on the electrode surface and improve insulation performance of a vacuum gap. The problems of insufficient conditioning and deconditioning effect during conventional voltage conditioning process of the vacuum interrupter can be solved. Therefore, insulation strength of the vacuum interrupter can be raised to a higher level through conditioning.

A pulse voltage conditioning method of a vacuum interrupter with automatic conditioning energy adjustment based on a trend of a breakdown voltage of the vacuum interrupter during a conditioning process. A current-limiting resistor and a parallel capacitor are automatically adjusted to ensure the conditioning energy reaching a critical value without deconditioning effect. The critical value refers to a maximum conditioning energy without damaging the electrode surfaces, namely an optimal conditioning energy, which can better remove insulation defects on the electrode surface and improve insulation performance of a vacuum gap. The problems of insufficient conditioning and deconditioning effect during conventional voltage conditioning process of the vacuum interrupter can be solved. Therefore, insulation strength of the vacuum interrupter can be raised to a higher level through conditioning.

A sensor system for measuring an angle of a gate of an isolating switch of overhead lines, comprising an optical fiber angle sensor, a base, a support plate, a light source fiber, a laser transmitter, an aluminum box, a relay, a step-down power module, a control circuit board, a photoelectric converter, and a receiving optical fiber. The support plate is arranged on an upper part of a pillar insulator; the optical fiber angle sensor is arranged on the base to detect a rotation angle of the gate; the laser transmitter is controlled to emit a laser beam into the light source fiber; the laser beam is received by the receiving optical fiber and transmitted to the photoelectric converter to convert a light intensity into a voltage signal; the converted voltage signal is transmitted to the control circuit board for processing, and the angle of the gate is output.