An anti-power environment suppression circuit includes: a power input terminal configured to receive an alternating current input from an external power source; a power output terminal configured to output the alternating current that has undergone anti-interference processing; a live wire, a neutral wire and a ground wire that are coupled in parallel between the power input terminal and the power output terminal; and a common-mode suppression sub-circuit coupled in the ground wire. The common-mode suppression sub-circuit is further coupled to the live wire and the neutral wire, and the common-mode suppression sub-circuit is configured to suppress common-mode interference between the ground wire and the live wire, and suppress common-mode interference between the ground wire and the neutral wire, so as to perform the anti-interference processing on the input alternating current.

An anti-power environment suppression circuit includes: a power input terminal configured to receive an alternating current input from an external power source; a power output terminal configured to output the alternating current that has undergone anti-interference processing; a live wire, a neutral wire and a ground wire that are coupled in parallel between the power input terminal and the power output terminal; and a common-mode suppression sub-circuit coupled in the ground wire. The common-mode suppression sub-circuit is further coupled to the live wire and the neutral wire, and the common-mode suppression sub-circuit is configured to suppress common-mode interference between the ground wire and the live wire, and suppress common-mode interference between the ground wire and the neutral wire, so as to perform the anti-interference processing on the input alternating current.

The present application provides a wind turbine and a converter filter capacitor switching control method, device and system therefor. The method includes: acquiring a contactor delay influence factor of the converter and an approximate zero voltage period of the power grid connected to the wind turbine, wherein an absolute value of a voltage of the power grid in the approximate zero voltage period is less than an approximate zero voltage threshold; obtaining a contactor delay duration according to the contactor delay influence factor, wherein the contactor delay duration is a duration from when the contactor receives a switching instruction to when the contactor is switched on or off; determining a switching time point of the filter capacitor based on the approximate zero voltage period and the contactor delay duration; transmitting the switching instruction to the contactor when the switching time point is reached.

A converter apparatus includes a string of electrically interconnected modules that includes a first group of modules comprising a first module and a second group of modules comprising a second module. A first screen is connected to a first defined electric potential and is located adjacent the first group of modules and a second screen is connected to a second defined electric potential and is located adjacent the second group of modules. During operation of the converter apparatus a resonance loop is created from the first module via the first and second screens and the second module back to the first module. A damping unit is located in the resonance loop and is set to dampen electromagnetic noise.

A converter apparatus includes a string of electrically interconnected modules that includes a first group of modules comprising a first module and a second group of modules comprising a second module. A first screen is connected to a first defined electric potential and is located adjacent the first group of modules and a second screen is connected to a second defined electric potential and is located adjacent the second group of modules. During operation of the converter apparatus a resonance loop is created from the first module via the first and second screens and the second module back to the first module. A damping unit is located in the resonance loop and is set to dampen electromagnetic noise.

Embodiments of present disclosure relate to an apparatus and a method for controlling a delta-connected cascaded multilevel converter. The apparatus (100) for controlling a delta-connected cascaded multilevel converter (110) comprises: a converter controller (102) configured to: receive current signals indicating phase currents flowing through respective phase arms of the converter (110); determine a harmonic current signal indicating a circulating current of the converter (110) from the current signals; and generate, based on the determined harmonic current signal and a reference current signal, a harmonic voltage signal to cause an amplitude of the circulating current flowing through the phase arms of the converter (110) to be a predetermined amplitude.

Embodiments of present disclosure relate to an apparatus and a method for controlling a delta-connected cascaded multilevel converter. The apparatus (100) for controlling a delta-connected cascaded multilevel converter (110) comprises: a converter controller (102) configured to: receive current signals indicating phase currents flowing through respective phase arms of the converter (110); determine a harmonic current signal indicating a circulating current of the converter (110) from the current signals; and generate, based on the determined harmonic current signal and a reference current signal, a harmonic voltage signal to cause an amplitude of the circulating current flowing through the phase arms of the converter (110) to be a predetermined amplitude.

A method for stabilizing a DC link voltage of an electrical converter, the method including: determining a DC link voltage signal for the DC link voltage of the electrical converter; determining a fluctuation signal of the DC link voltage by applying a high pass filter to the DC link voltage signal; determining a torque offset by multiplying the fluctuation signal with a gain value; and modifying a reference torque with the torque offset for controlling the electrical converter. The gain value is adjusted by: determining a DC link voltage ripple from the DC link voltage signal; and comparing the DC link voltage ripple with a threshold and, when the DC link voltage ripple is higher than the threshold, increasing the gain value.

A method for stabilizing a DC link voltage of an electrical converter, the method including: determining a DC link voltage signal for the DC link voltage of the electrical converter; determining a fluctuation signal of the DC link voltage by applying a high pass filter to the DC link voltage signal; determining a torque offset by multiplying the fluctuation signal with a gain value; and modifying a reference torque with the torque offset for controlling the electrical converter. The gain value is adjusted by: determining a DC link voltage ripple from the DC link voltage signal; and comparing the DC link voltage ripple with a threshold and, when the DC link voltage ripple is higher than the threshold, increasing the gain value.

A microgrid with a high voltage direct current (HVDC) source for efficiently and safely distributing power to decentralized loads includes: at least a main HVDC power supply connectable in input to an AC grid and in output to a main DC distribution network and loads system in output, the main HVDC power supply having energy reserve means and a main switch-based fault isolator or main FI, the main DC distribution network and loads system including: a maintrunk bus, and subtrunks buses and/or front end local loads cells connected in parallel to the maintrunk bus, and at each branching of a subtrunk bus and a load or of a subtrunk bus of rank n−1 and a subtrunk bus of rank n, a local switch-based fault isolator or local FI, n being an integer comprised in the range [1, N]. A smart main controller including microcontrollers for smart operation is also included.