A method for determining a function of a capacitor of a passive filter circuit, which partially reduces line-conducted interference of an electrical device electrically coupled to a power supply system via the passive filter circuit. The passive filter circuit comprises the capacitor having a predefined capacitance value and a choke having a predefined inductance value. An electric capacitor voltage on the capacitor is detected. A connection voltage of the electrical device is detected. Spectral components are determined for the capacitor voltage and the connection voltage. The function of the capacitor is determined by analysing the spectral components in consideration of the inductance value of the choke by a statistical processing operation.

The present invention discloses a method for quickly eliminating ferromagnetic resonance of a voltage transformer. The method includes: first sampling a three-phase voltage and an open-delta voltage of a voltage transformer; calculating a flux linkage corresponding to a zero-sequence voltage by means of an integral algorithm; and when detecting that ferromagnetic resonance occurs in the mutual inductor, further checking whether the absolute value of the flux linkage corresponding to the zero-sequence voltage or the absolute value of the open-delta voltage respectively falls within a set range, and if yes, starting a secondary resonance elimination loop for resonance elimination. The present invention also discloses a corresponding device for quickly eliminating ferromagnetic resonance of a voltage transformer. The present method and device accurately analyze and control resonance elimination trigger time based on a conventional secondary resonance elimination principle, and can effectively eliminate the impact of the core saturation of a voltage transformer on a resonance elimination process, thereby greatly improving the success probability of single resonance elimination.

A protective device protects an LC filter in a vehicle. The vehicle includes a first vehicle-mounted electric device and a second vehicle-mounted electric device. The first vehicle-mounted electric device includes a first power converter. The second vehicle-mounted electric device includes a second power converter and shares a power supply with the first vehicle-mounted electric device. The LC filter is arranged between the first power converter and the power supply. The LC filter is configured such that the resonance frequency band of the LC filter can be changed. The resonance frequency band of the LC filter is changed based on a ripple amount in a current flowing in the LC filter.

The present invention discloses a parameter tuning approach for bypass damping filter to suppress subsynchronous resonance in power systems, namely determining the parameters of capacitor, inductor and damping resistor in BDF. Using this approach, the parameters of capacitor and inductor in BDF can be adjusted, so that the frequency where the negative electrical damping of generator reaches minimum can be away from the frequency range of low frequency oscillation mode and typical frequencies of each torsional mode; the parameter of damping resistor in BDF can be further adjusted so that the minimum value of negative electrical damping is in reasonable range. The application of BDF with parameters tuned by the present invention contributes to the suppression of both the torsional interaction effect and the transient torque amplification effect.

The present disclosure pertains to systems and methods for monitoring a capacitance-coupled voltage transformer (CCVT) in electrical communication with the electric power delivery system, the CCVT comprising a stack of capacitors and an electrical contact to a first ground connection. A first current transformer is disposed between the stack of capacitors and the first ground connection. The current transformer provides an electrical signal corresponding to a current associated with the CCVT. A second current transformer is disposed between a primary winding of a step-down transformer associated with the CCVT and a second ground connection. An intelligent electronic device (IED) in electrical communication with the current measurement devices monitors a ratio of magnitudes from the current transformers at a single frequency. The ratio is compared against an acceptable range. When the ratio exceeds the acceptable range, an alarm is generated.

The present disclosure relates to the technical field of potential transformer (PT) ferromagnetic resonance elimination, in particular to a PT ferromagnetic resonance elimination method implemented by actively inputting resistance through an electronic load, including the following steps: setting up a PT, and determining a mapping relationship; constructing a resonance elimination control system; and designing the electronic load as an active resonance elimination device. The present disclosure overcomes a contradiction between a magnitude of resonance elimination resistance and winding overload in a PT open delta during single-phase-to-earth fault and fault clearance, and effectively avoids the technical problems of difficult distinguishing between single-phase-to-earth fault characteristics and power frequency resonance characteristics and causing resonance in a single-phase-to-earth fault process. Compared with previous disclosure designs, the present disclosure directly measures parameters, and is simple in algorithm, low in computational complexity, rapid in arithmetic speed, high in precision and less in error.

A method for determining a function of a capacitor of a passive filter circuit, which partially reduces line-conducted interference of an electrical device electrically coupled to a power supply system via the passive filter circuit. The passive filter circuit comprises the capacitor having a predefined capacitance value and a choke having a predefined inductance value. An electric capacitor voltage on the capacitor is detected. A connection voltage of the electrical device is detected. Spectral components are determined for the capacitor voltage and the connection voltage. The function of the capacitor is determined by analysing the spectral components in consideration of the inductance value of the choke by a statistical processing operation.

The present disclosure pertains to systems and methods for monitoring a capacitance-coupled voltage transformer (CCVT) in electrical communication with the electric power delivery system, the CCVT comprising a stack of capacitors and an electrical contact to a first ground connection. A first current transformer is disposed between the stack of capacitors and the first ground connection. The current transformer provides an electrical signal corresponding to a current associated with the CCVT. A second current transformer is disposed between a primary winding of a step-down transformer associated with the CCVT and a second ground connection. An intelligent electronic device (IED) in electrical communication with the current measurement devices monitors a ratio of magnitudes from the current transformers at a single frequency. The ratio is compared against an acceptable range. When the ratio exceeds the acceptable range, an alarm is generated.

A device for generating electrical energy, in particular a wind turbine, having at least one generator is disclosed. The generator provides electrical energy by means of multi-phase, machine-side connection means and is connected to at least one converter having a DC link via the multi-phase, machine-side connection means. A method for operating a device for generating electrical energy, in particular a wind turbine, is also disclosed. The object of providing a device for generating electrical energy, in particular a wind turbine, which reliably avoids the development of surges despite parasitic inductances and capacitances by means of the machine-side multi-phase connection means is achieved in that means for attenuating at least one series resonance in the zero sequence of the machine-side connection means are provided between generator and converter.

An electromagnetic interference (EMI) suppression circuit is interposed between an AC source and a DC power conversion system. The EMI suppression circuit includes a pi-type filter network having first and second filter input terminals and having first and second filter output terminals. The pi-type filter network includes a common mode choke and a differential mode choke between the input terminals and the output terminals. The pi-type filter network includes a first X-type capacitor across the first and second filter input terminals and includes a second X-type capacitor across the first and second filter output terminals. A first Y-type emission reduction capacitor is connected between the first filter input terminal and earth ground. At least a second Y-type emission reduction capacitor and a damping resistor are connected in series to form a series resistor-capacitor combination between the first filter output terminal and earth ground.