Abstract: The present disclosure relates to a method for preventing a maloperation of differential protection of an optical fiber caused by saturation of a single Current Transformer (CT) of 3/2 connection. By applying a combination of the differential judgment and the sub-CT current judgment, reliable identification of internal and external faults is ensured, and the problem of misjudging of the internal fault as the external fault can be prevented as well.

Abstract: The present disclosure relates to a method for quickly identifying disconnection of a Current Transformer (CT) in protection of a 3/2 connection mode based bus. The present disclosure can quickly and accurately identify the disconnection of the CT, thereby avoiding the problem of a maloperation in protection of a bus caused by the disconnection of the CT.

Abstract: The present invention relates to a prevention method of abnormal action protection of UHV regulating compensation transformer with no-load input, the prevention method includes: first determining a value of differential current of regulating compensation transformer, if the value of differential current is smaller than a pre-setting threshold, then, identifying whether an uninterruptible point of differential current waveform meets an pre-setting regulation according to original value of differential current or sampling value of differential difference current, and determining comprehensively whether the regulating compensation transformer is in no-load input or in fault directly with a value of second harmonic content of logic differential current together; if a value of differential current before pre-setting period is larger than the pre-setting threshold, the regulating compensation transformer is diagnosed to have external CT saturation, determining comprehensively whether the regulating compensation tra

Abstract: Sampling implementation method and device based on conventional sampling GOOSE trip mode. CPU of master NPI plug-in, after receiving a second pulse, transmits sampling pulse generation time and a transmission enable bit to FPGA of the master NPI plug-in at a fixed interval; after detecting the transmission enable bit, the FPGA of the master NPI plug-in judges whether time of its internal timer is greater than/equal to the sampling pulse generation time, if yes, generates a sampling pulse to FPGA of collection plug-in; after receiving sampling pulse, the collection plug-in carries out A/D sampling, and transmits sampled data to the master NPI plug-in; when detecting that all A/D samplings are completed, the master NPI plug-in transmits data packets to protection CPU plug-in. The device includes an MMI plug-in, a protection CPU plug-in, a master NPI plug-in and a collection plug-in. Protection maloperation is thereby reduced.

Abstract: The present disclosure relates to a method for quickly identifying disconnection of a Current Transformer (CT) in protection of a 3/2 connection mode based bus. The present disclosure can quickly and accurately identify the disconnection of the CT, thereby avoiding the problem of a maloperation in protection of a bus caused by the disconnection of the CT.

Abstract: The present disclosure relates to a method for preventing a maloperation of differential protection of an optical fiber caused by saturation of a single Current Transformer (CT) of 3/2 connection. By applying a combination of the differential judgment and the sub-CT current judgment, reliable identification of internal and external faults is ensured, and the problem of misjudging of the internal fault as the external fault can be prevented as well.

Abstract: Sampling implementation method and device based on conventional sampling GOOSE trip mode. CPU of master NPI plug-in, after receiving a second pulse, transmits sampling pulse generation time and a transmission enable bit to FPGA of the master NPI plug-in at a fixed interval; after detecting the transmission enable bit, the FPGA of the master NPI plug-in judges whether time of its internal timer is greater than/equal to the sampling pulse generation time, if yes, generates a sampling pulse to FPGA of collection plug-in; after receiving sampling pulse, the collection plug-in carries out A/D sampling, and transmits sampled data to the master NPI plug-in; when detecting that all A/D samplings are completed, the master NPI plug-in transmits data packets to protection CPU plug-in. The device includes an MMI plug-in, a protection CPU plug-in, a master NPI plug-in and a collection plug-in. Protection maloperation is thereby reduced.

Abstract: The present invention relates to a prevention method of abnormal action protection of UHV regulating compensation transformer with no-load input, the prevention method includes: first determining a value of differential current of regulating compensation transformer, if the value of differential current is smaller than a pre-setting threshold, then, identifying whether an uninterruptible point of differential current waveform meets an pre-setting regulation according to original value of differential current or sampling value of differential difference current, and determining comprehensively whether the regulating compensation transformer is in no-load input or in fault directly with a value of second harmonic content of logic differential current together; if a value of differential current before pre-setting period is larger than the pre-setting threshold, the regulating compensation transformer is diagnosed to have external CT saturation, determining comprehensively whether the regulating compensation tra

Abstract: The invention relates to a frequency measuring method and measuring device. The method comprises: firstly sampling the current signal to be measured, and discretizing the sampled signals; secondly obtaining sampling matrixes [In] and [In,] of the current signal to be measured at time n and time n?1 from the discrete sampled signals, setting a reference frequency fref, constructing a reference voltage signal u(t) from fref, and discretizing u(t) to gain reference matrix; finally, attaining phase values of time n and time n?1 from the eigenvalues of matrixes [In]+[U] and [In?1]+[U], and determining a calculation frequency fcomp. The invention uses sampled matrixes constructed from the reference signals and the signals to be measured.