Abstract: Provided are a method and apparatus for evaluating a degree of frequency regulation urgency of a generator set, a power system and a storage medium.

Abstract: A method for calculating the steady-state fault current of a modular multilevel converter (MMC) comprises calculating the dc-side critical resistance values RA/B, RB/C and RC/D of the MMC based on the bridge arm inductance coefficient k and the ac-side reactance Xac of the MMC; Then, determining the operating modes of the MMC based on RA/B, RB/C and RC/D, and calculating the steady-state dc fault current and the conduction overlap angle respectively under various operating modes without considering the ac-side resistance based on the parameters k, Us, Rdc and the dc-side critical resistance values RA/B, RB/C and RC/D; After that the steady-state AC fault current amplitude and phase angle for each operating mode without considering the AC side resistance are calculated based on the DC current and conduction overlap angle for each operating mode, respectively. Finally, the steady-state AC fault current amplitude and phase angle are calculated for various operating modes considering the AC side resistance.

Abstract: The present disclosure relates to a method for protecting DC line impedance phase based on protection and control coordination, and an application scenario of the method for protecting is a three-terminal flexible DC transmission network. The method uses high controllability of a converter after a fault, injects a characteristic signal at a characteristic frequency, and calculates a phase angle of input impedance to determine a fault interval, which effectively improves protection performance, turns passive to active, and is not affected by nonlinearity of the converter. At the same time, compared with a full-bridge MMC, using a half-bridge MMC does not need to perform fault ride-through first when identifying a fault, and does not need to add additional equipment, it creates fault features and can reliably identify an fault interval; improves protection quickness and at the same time also has better economic benefits.

Abstract: A method for calculating the steady-state fault current of a modular multilevel converter (MMC) comprises calculating the dc-side critical resistance values RA/B, RB/C and RC/D of the MMC based on the bridge arm inductance coefficient k and the ac-side reactance Xac of the MMC; Then, determining the operating modes of the MMC based on RA/B, RB/C and RC/D, and calculating the steady-state dc fault current and the conduction overlap angle respectively under various operating modes without considering the ac-side resistance based on the parameters k, Us, Rdc and the dc-side critical resistance values RA/B, RB/C and RC/D; After that the steady-state AC fault current amplitude and phase angle for each operating mode without considering the AC side resistance are calculated based on the DC current and conduction overlap angle for each operating mode, respectively. Finally, the steady-state AC fault current amplitude and phase angle are calculated for various operating modes considering the AC side resistance.

Abstract: Embodiments of the present disclosure provide an opening and closing mechanism and a leakage protection device. The opening and closing mechanism comprises: a stationary contact and a movable contact, which contacts the stationary contact at ON-position and separates from the stationary contact at OFF-position; a first magnetic assembly; and a second magnetic assembly that is integrally rotatable about an axis, the second magnetic assembly comprising: an electric conductor onto which the movable contact is mounted; and a magnetic body comprising at least one magnetic portion configured to rotate about the axis under a magnetic force from the first magnetic assembly, to correspondingly drive the movable contact to rotate between the ON-position and the OFF-position, wherein a distance from each of the at least one magnetic portion to the axis is smaller than a distance from the movable contact to the axis.

Abstract: A full-ocean-depth fidelity enzymological measurement device for microbial extracellular enzyme is provided, comprising a pressure-maintaining sampling bottle, pressure-maintaining transfer equipment, a pressure-maintaining enzymological reactor, and heat preservation equipment and enzyme activity detection equipment. The pressure-maintaining enzymological reactor comprises a barrel body, a plug, polytetrafluoroethylene gaskets, an O-ring, a piston, a high-pressure straight-through valve, and a high-pressure connector. The pressure-maintaining enzymological reactor is in a closed barrel body shape and is internally provided with the piston, and the plug and the valve are arranged at each of two ends of the pressure-maintaining enzymological reactor; and the valve is connected to the pressure-maintaining transfer equipment through the high-pressure connector.

Abstract: It discloses a ring-connected bridge-type multi-port hybrid DC circuit breaker. When the number of ports is n, n is an integer greater than or equal to 2, the ring-connected bridge-type multi-port hybrid DC circuit breaker includes: an upper DC bus bar, a lower DC bus bar, n thyristor arms, n diode arms, a main breaker branch, and n bypass branches; each thyristor arm connects in series with a diode arm, forming a series circuit; a bypass branch is connected between every two adjacent series circuits, a port is provided at the connection point of the thyristor arm and the diode arm in each series circuit, and the port is used to connect the protected components or the DC lines.

Abstract: Disclosed embodiments relate to a socket. A speed-control switch, including: a housing including a top plate provided with a central opening extending in a length direction; a push rod at least partially contained in the housing, and a first end of the push rod protruding out of the housing from the central opening and capable of sliding in the central opening; a plurality of connection terminals provided in pairs in the housing and configured to: selectively engage with a second end of the push rod opposite to the first end to limit a plurality of speed indications of the speed-control switch; and a speed selection assembly with a part thereof set on the top plate and configured to allow a selection for a plurality of speed indications of the speed-control switch as the push rod slides in the central opening. The speed-control switch achieve speed switching with a small force.

Abstract: Disclosed embodiments relate to a socket. A speed-control switch, including: a housing including a top plate provided with a central opening extending in a length direction; a push rod at least partially contained in the housing, and a first end of the push rod protruding out of the housing from the central opening and capable of sliding in the central opening; a plurality of connection terminals provided in pairs in the housing and configured to: selectively engage with a second end of the push rod opposite to the first end to limit a plurality of speed indications of the speed-control switch; and a speed selection assembly with a part thereof set on the top plate and configured to allow a selection for a plurality of speed indications of the speed-control switch as the push rod slides in the central opening. The speed-control switch can achieve speed switching with a small force.

Abstract: It discloses a ring-connected bridge-type multi-port hybrid DC circuit breaker. When the number of ports is n, n is an integer greater than or equal to 2, the ring-connected bridge-type multi-port hybrid DC circuit breaker includes: an upper DC bus bar, a lower DC bus bar, n thyristor arms, n diode arms, a main breaker branch, and n bypass branches; each thyristor arm connects in series with a diode arm, forming a series circuit; a bypass branch is connected between every two adjacent series circuits, a port is provided at the connection point of the thyristor arm and the diode arm in each series circuit, and the port is used to connect the protected components or the DC lines.

Abstract: Embodiments of the present disclosure provide a bracket, a functional module and a mounting method of an electrical device. The bracket described herein includes a body comprising a supporting portion adapted to support a functional component of the electrical device, a first coupling portion and a second coupling portion symmetrically arranged on the body with respect to a longitudinal axis of the supporting portion, and the second coupling portion is adapted to be coupled with the first coupling portion of a further bracket of the same specification to form a bracket set. The bracket described herein can be interlocked together, and the mounting component and the bracket are integrally formed. As a result, the appearance of the electrical device is improved, more mounting screws are saved, the mounting steps of the electrical device are reduced, and the mounting efficiency of the electrical device is improved.