Takaaki Sakakibara

Simulation of Propagating Electromagnetic Wave Due to Partial Discharge in GIS Using FDTD

It takes a lot of trouble to measure and calibrate the sensitivity of ultra-high-frequency couplers which are set in various gas-insulated switchgears (GIS). This paper is related to the approach of calculating the attenuation of the electromagnetic (EM) wave due to the partial discharge propagating through insulators constituting a GIS. The use of a simulator based on the finite-difference time-domain method for analyzing the three-dimensional transient EM fields shows the degree of precision of the modeling descriptions employed and their ability to confirm experimental results.

On-site measurement for the development of on-line partial discharge monitoring system in GIS

This paper deals with the results of field tests carried out to develop an online sensor for monitoring partial discharges generated in the GIS. It covers noise distribution in the GIS tank, the propagation of partial discharge pulses, and its mechanisms, while presenting applications of partial discharge online monitoring sensors. >

Study of propagation phenomena of partial discharge pulses in gas insulated substation

This paper describes the results of tests and discussions carried out to develop a system for monitoring partial discharges generated in gas-insulated substations (GIS). They include the propagation characteristics and the mechanisms of partial discharge pulses in the GIS, the results of computer simulation, and the results of comparisons with previous tests to verify the partial discharge locating method.

PD Signal Propagation Characteristics in GIS and Its Location System by Frequency Components Comparison

Propagation characteristics of partial discharge (PD) signal in gas-insulated switchgear (GIS) were investigated in a laboratory and at a 300 kV underground substation. The laboratory test indicates that signal damping can be attributed to two major mechanisms: reflection due to irregularity of characteristic impedance such as spacers and the mode shift from TEM to TE or TM. Tests at the substation show that the signal damping phenomena are independent of propagation direction and the mode shift gives rise to a large signal damping. The major higher mode seems to be TE11. Amplitudes of observed waveforms using narrow-band filters that agree well with the corresponding frequency components observed with a spectrum analyzer show irregular or random behavior depending upon their observation point. This indicates that narrow-band filters do not seem to be suitable for a PD location system by a frequency component comparison, and the reliability of the system using broadband filters instead is discussed.

Application of gas pressure sensor for fault location system in gas insulated substation

This paper reports on increasing the sensitivity of a gas-insulated substation (GIS) fault location system using gas pressure sensors. It describes the results of studies on engineering problems arising where methods and sensors for this purpose are actually applied, while presenting the results of performance proof tests carried out with actual equipment, together with some results of their analysis. >

Distribution of Induced Grounding Current in Large-Capacity Gis Using Multipoint Grounding System

This paper deals with the distribution of induced grounding current in a large-capacity full GIS using a multipoint grounding system, while referrring to main points in applying a multipoint grounding system in large-capacity GISs.

Simulation of propagating electromagnetic wave due to partial discharge in GIS using FDTD

It takes a lot of trouble to measure and calibrate the sensitivity of ultra-high-frequency couplers which are set in various gas-insulated switchgears (GIS). This paper is related to the approach of calculating the attenuation of the electromagnetic (EM) wave due to the partial discharge propagating through insulators constituting a GIS. The use of a simulator based on the finite-difference time-domain method for analyzing the three-dimensional transient EM fields shows the degree of precision of the modeling descriptions employed and their ability to confirm experimental results.

Sensitivity of UHF coupler and loop electrode with UHF method and their comparison for detecting partial discharge in GIS

We introduce in this paper the sensitivity of two UHF couplers, disc-type measuring electrode and loop-type measuring electrode embedded in an epoxy insulator, for detecting partial discharge (PD) and diagnosing GIS. Each of the couplers has sufficient performance for detecting the electromagnetic waves up to 8 GHz. The attenuation characteristic of electromagnetic waves is changed depending upon the location of defects, such as a particle on an enclosure or on a conductor.

Development of coaxial-to-waveguide antenna attached outer GIS for detecting partial discharge

We have developed a coaxial-to-waveguide antenna that is capable of being attached to outer insulators in GIS. We firstly obtained the sensitivity line between output of the antenna (mV) and magnitude of partial discharge (pC) that is obtained based on IEC 60270. We also compared spectra measured by the coaxial-to-waveguide antenna from those measured by both spiral antenna and disc coupler so as to clarify frequency response and attenuation characteristics of the coaxial-to-waveguide antenna.

Development of GIS fault location system using pressure wave sensors

This paper describes a series of development tests carried out when developing a GIS (gas insulated substation) fault location system using pressure wave sensors for a GIS with a main bus in which each gas section per bay is connected by gas piping. This paper also refers to the basic construction of the software of the fault location system actually applied to a GIS with a rated voltage of less than 168 kV.