A power converter for heat tracing applications is disclosed. The power converter includes a controller configured to control an input switching stage. The power converter also includes an output filter, the output filter electrically coupled to the input switching stage. Further, the power converter includes a passive cooling element, the passive cooling element coupled to the power converter. The controller is configured to select a peak voltage and set a power converter output voltage based on at least one of the peak voltage and a power converter input voltage. The passive cooling element is configured to decrease a temperature of the power converter and to obviate the need for cooling with moving parts, making the system viable for hazardous areas in addition to non-hazardous areas. The input switching stage includes a plurality of transistors. The power converter output voltage and the power converter input voltage are both alternating current.

A transformer arrangement comprising a transformer having a primary side for receiving input voltage and current from a source and a secondary side for providing output voltage and current to a load. The transformer arrangement further comprises an AC-AC PE converter connected to a thyristor used for bypassing the AC-AC PE converter in case of a short-circuit fault in a terminal of the primary side and/or the secondary side. The transformer arrangement further comprises a thyristor-based AC-AC PE converter connected to a thyristor-tapped winding. The AC-AC PE converter is connected with the thyristor-tapped winding via the thyristor-based AC-AC PE converter. The thyristor-based AC-AC PE converter is connected to an impedance to protect the thyristor-tapped winding from short-circuit faults of the thyristor-based AC-AC PE converter.

A transformer arrangement comprising a transformer having a primary side for receiving input voltage and current from a source and a secondary side for providing output voltage and current to a load. The transformer arrangement further comprises an AC-AC PE converter connected to a thyristor used for bypassing the AC-AC PE converter in case of a short-circuit fault in a terminal of the primary side and/or the secondary side. The transformer arrangement further comprises a thyristor-based AC-AC PE converter connected to a thyristor-tapped winding. The AC-AC PE converter is connected with the thyristor-tapped winding via the thyristor-based AC-AC PE converter. The thyristor-based AC-AC PE converter is connected to an impedance to protect the thyristor-tapped winding from short-circuit faults of the thyristor-based AC-AC PE converter.

A load control device for controlling the amount of power delivered from an AC power source to an electrical load is operable to conduct enough current through a thyristor of a connected dimmer switch to exceed rated latching and holding currents of the thyristor. The load control device comprises a controllable-load circuit operable to conduct a controllable-load current through the thyristor of the dimmer switch. The load control device disables the controllable-load circuit when the phase-control voltage received from the dimmer switch is a reverse phase-control waveform. When the phase-control voltage received from the dimmer switch is a forward phase-control waveform, the load control device is operable to decrease the magnitude of the controllable-load current so as to conduct only enough current as is required in order to exceed rated latching and holding currents of the thyristor.

A transformer device and a control method for the transformer device are provided. The transformer device includes a transformer, an uplink cascade connection port, a downlink cascade connection port, and a controller. The controller is enabled when the transformer receives an input electric power, and the controller determines whether the uplink cascade connection port is connected to an uplink transformer device. When the uplink cascade connection port is connected to the uplink transformer device, the controller detects a downlink external transformer device connected to the downlink cascade connection port, reports a detection result to the uplink transformer device, and obtains a control signal from the uplink cascade connection port. The controller converts the input electric power into an output electric power according to the control signal and the transformer.

There is provided a method and apparatus for controlling harmonics. For each device in an array of devices, a level of harmonic control is acquired to apply to an alternating current voltage powering the device. The level of harmonic control defines a period in a cycle of the alternating current voltage in which to drop the alternating current voltage. For each device in an array of devices, the alternating current voltage powering the device is controlled by dropping the alternating current voltage in the period defined by the acquired level of harmonic control.

A Voltage Source Converter control system for active damping of a resonance oscillation in the VSC includes a regular Phase-Locked Loop 2, and a slow PLL 3. The control system is arranged such that an imaginary part of the AD is obtainable from the slow PLL. The slow PLL is configured for having a closed-loop bandwidth which is less than a frequency, in a synchronous dq frame, of the resonance oscillation to be dampened.

A Voltage Source Converter control system for active damping of a resonance oscillation in the VSC includes a regular Phase-Locked Loop 2, and a slow PLL 3. The control system is arranged such that an imaginary part of the AD is obtainable from the slow PLL. The slow PLL is configured for having a closed-loop bandwidth which is less than a frequency, in a synchronous dq frame, of the resonance oscillation to be dampened.

The invention relates to a method and to a device for managing the operation of a lighting device (Lp) having capacitive impedance, the lighting device being supplied by an AC electric power supply network, the management device comprising means (SW1, SW2) for varying the duration of the supply of electric power to the lighting device upon each alternation of the electrical signal supplied by the AC electric power supply network, at least one resistor (R1, R2) for discharging the electric power stored by the lighting device, characterized in that the management device (10) comprises means for allowing the electric power stored in the lighting device to be discharged only when electric power is not supplied to the lighting device.

A load control device for controlling the power delivered from an AC power source to an electrical load includes a thyristor, a gate coupling circuit for conducting a gate current through a gate of the thyristor, and a control circuit for controlling the gate coupling circuit to conduct the gate current through a first current path to render the thyristor conductive at a firing time during a half cycle. The gate coupling circuit is able to conduct the gate current through the first current path again after the firing time, but the gate current is not able to be conducted through the gate from a transition time before the end of the half-cycle until approximately the end of the half-cycle. The load current is able to be conducted through a second current path to the electrical load after the transition time until approximately the end of the half-cycle.