Partial Discharge Detection Technology Research Articles

Detection technology of partial discharge in transformer based on optical signal

The detection of partial discharge (PD) in transformers is of great significance for preventing insulation defects from developing into insulation failures. Transformer partial discharge detection technology includes pulse current method, radio frequency measurement method, UHF method, ultrasonic detection method, gas chromatography, and optical detection method. Among them, the optical detection method has the characteristics of strong anti-electromagnetic interference ability, and the signal can be transmitted and received without loss. The optical detection method has unique advantages. In this paper, an optical signal measuring device for partial discharge inside the transformer is designed and fabricated, the typical insulation defect inside the transformer is simulated, and the optical signal characteristics of typical partial discharge are obtained. Compared with the pulse current method, it is found that the magnitude of partial discharge can be characterized by the integral of the optical signal. The characteristic of the optical signal phase resolved partial discharge (PRPD) spectrum of typical insulation defects is obtained. The PRPD spectrum of the optical signals of different defects is obviously different. It is feasible to draw the PRPD spectrum and identify the defect types according to the optical signal, which can be further applied to the identification of internal faults in transformers.

Elucidation of impedance frequency characteristics of cast resin transformer and application to partial discharge diagnostic method

AbstractIt is desired to establish an insulation diagnosis method for cast resin transformers (CRTrs), which is often used in distribution systems. Partial discharge (PD) detection is considered to be an effective method, but its phenomenon has not yet been clarified. This paper presents investigation on the frequency characteristics of PD generated inside CRTrs to improve PD detection technology. It is clarified that dominant frequency of PD signal detected by a high frequency current transformer (CT) depends on the frequency characteristics of the impedance between the primary and secondary windings. It is suggested that the dominant frequency could be predicted in advance by analysis using a high‐frequency equivalent circuit model of CRTrs. PD diagnostic technology that utilizes the frequency characteristics of the CRTrs impedance has also been proposed. It is found that a PD generated external to CRTrs does not have resonance at the dominant frequency of the CRTrs itself, even though it passes through the CRTrs. In conclusion, it is suggested that the frequency analysis of CRTrs impedance could identify degraded CRTrs and external noise.

A Pulse Interference Suppression Method Based on Double-Sensor Detection for PD Measurement in Frequency-Tuned Resonant Tests

In the previous study, we proposed an adaptive pulse separation algorithm to separate the pulse-shaped interferences in frequency-tuned resonant (ACRF) tests. However, the interference separation effect of this algorithm was limited in the long test cable and low interference amplitude condition. In this study, a double-sensor detection method is proposed to suppress pulse-shaped interference generated by ACRF systems, to realize the partial discharge (PD) measurement for long cable equipment. First, the transmission characteristics of pulse interference in the ACRF system are analyzed. Then, the principle of the double-sensor-based PD detection technology is introduced; this entails simultaneous using an antenna to acquire the interference of the variable-frequency source and a high-frequency current transformer to collect the PD signals and interference at the test object, then realizing the interference suppression by calculating the intersection of the time series of the two sets of pulse signals. Finally, the effectiveness of the proposed method is validated by performing ACRF tests on a 400-m cable. The experimental results show that this method can effectively realize the suppression of pulse-shaped interference in long-cable ACRF tests. The proposed method provides a feasible way for noise suppression in intense pulse-shaped interference environments.

Analysis of Partial Discharge Spectrum Based on Ultra-High Frequency Detection Method

Oil immersed power transformer is the most widely used large power transformer in power system and its insulation structure is mainly composed of oil, paper and other solid insulation materials. Partial discharge monitoring is an effective means to find dielectric faults of transformer in an early stage of development. Ultra-high frequency(UHF) partial discharge detection technology has high detection frequency and strong anti-interference ability, which is suitable for transformer online detection. In this paper, five typical transformer discharge models are built, and the discharge spectra of each model are measured by a UHF sensor. The test results show that the surface discharge and wedge discharge most occurs near the voltage peak, the discharge phase distribution of floating part discharge is very wide, the internal air gas discharge mostly occurs in the area where the absolute value of voltage increases, and the point-to-plane discharge has a typical polarity effect.

Multi-Physical Tracking and Sensing Technology of Switchgear Partial Discharge Based on Edge Computing and Smart Gateway

In view of the high bottleneck of current partial discharge detection technology, strong professionalism and heavy detection tasks, the partial discharge process is greatly affected by the equipment operating environment and condition factors. The paper proposes a switching device partial discharge multiphysics based on edge computing. Research on perception and state tracking technology. The article aims at the edge computing technology of multi-physical partial discharge signal feature extraction, the construction of multi-physical tracking over-limit early warning model, and the development and trial production of intelligent gateway technology. The research found that the edge computing algorithm proposed in the paper can effectively reduce the cost and power consumption under the premise of ensuring the performance of the detection system.

Method of GIL partial discharge localization based on natural neighbour interpolation and ECOC‐MLP‐SVM using optical simulation technology

Partial discharge (PD) is one of the main causes rendering the deterioration of the insulation state in gas-insulated transmission line (GIL). Accurate and timely localization of the PD source is essential to ensure the safe and stable operation of the GIL. At present, optical PD detection technology shows advantages in terms of high sensitivity and strong anti-interference performance. Therefore, an optical PD localization method based on optical simulation fingerprint database is proposed. The introduction of simulation conquers the difficulty of obtaining a PD fingerprint database in field experiments. This method constructs a simulation fingerprint database by performing PD simulation in a GIL simulation model of the same size as the actual GIL. The natural neighbour interpolation algorithm is applied to expand the simulation fingerprint database to cover all locations in the GIL. The two-level localization method proposed is to match the PD fingerprint to be tested with the expanded fingerprint database, which can reduce the amount of calculation while maintaining the localization accuracy. The experimental results show that the average localization error of this method is only 9.7 mm, and the localization time is reduced by about 11 times compared with the normal one-level localization method.

Distributed Partial Discharge Detection Technology for High Voltage Cable Based on Ac Withstand Voltage

with the Development of Urbanization, It is More and More Urgent to Improve the Reliability and Stability of Power Supply. Due to the Consideration of Municipal Planning, Environment, Personal Safety and Other Factors, the Utilization Rate of Power Cables in Urban High-Voltage Transmission Channels Has Increased Dramatically. Accidents Such as Fire, Large-Area Power Failure and So on, Which Are Caused by Internal Insulation Defects of Cables, Defects in Joint Position Fabrication and Installation Process, Occur from Time to Time. This Paper Studies the Detection Method of Potential Insulation Defects in the Cable Interior and Joint Position Based on the Ac Withstand Voltage Partial Discharge Detection Technology, and Designs a Set of Distributed Partial Discharge Test System Based on the High Frequency Pulse Method to Detect the Interior, Middle Indirect Head and Terminal Head of the Cable. in the Field, the Distributed Pd Detection Technology Based on Ac Withstand Voltage Designed in This Paper Can Effectively Detect the Internal and Joint Insulation Defects of Power Cables, and Realize Fault Location, Which Has the Value of Practical Application and Promotion.

Analysis and Treatment of the Cause of Heating of Single-core XLPE Cable GIS Terminal

In this paper, the heat generation of 110kV cable GIS terminal discovered by infrared thermal imager is briefly described. The causes of heat generation are discussed by means of sheath current detection and circulation calculation, and further analysed by high frequency partial discharge monitoring system, timely handling of equipment hidden dangers, to avoid the occurrence of vicious accidents. Through the analysis and judgment of this accident, the significance of infrared temperature measurement, sheath current detection technology and high frequency partial discharge detection technology for the discovery of cable defects is proved, which provides a basis and reference for future work.

Case Analysis on Partial Discharge Signal of XLPE Cable T-Joint by Using High-Frequency Pulse Current Method

The cable joint is a vital part of cable lines which cause defects and faults easily and through partial discharge (PD) test internal discharge can be noticed. In this paper, we study a suspected PD signal which was found in the T-joint and intermediate joints nearby during a 110kV XLPE cable partial discharge (PD) test. Through the high-frequency PD detection technology, the discharge signal was positioned from the inside of T-joint. A trace of discharge was found at the air gap of the metal ring and the epoxy sleeve in the front of the T-joint stress cone. It is further verified that high-frequency PD detection technique can be used to locate the position of discharge.

Research on the Optical Properties of Transformers Partial Discharge Based on Different Discharge Models

In this paper, the different types of discharge in transformer were simulated based on the real transformer fault model. The optical partial discharge detection system was established based on optical sensors which were capturing partial discharge accompanied by optical effects. In this research, surface discharge and suspended discharge defect model was pressurized to generate partial discharge signal. The results showed that: Partial discharge optical signals could effectively respond the production and development process of transformer partial discharge. It was able to assess discharge level also. When the discharge phenomenon stabilized, the phase of surface discharge mainly between 60°~150°and 240°~330°, the phase of suspended discharge mainly between 260°~320°. According to the phase characteristic of discharge pattern, the creeping discharge and suspended discharge phenomenon of transformer can be distinguished. It laid the foundation for the application of transformer optical partial discharge detection technology.

Application of Partial Discharge Online Monitoring Technology in ± 660kV Converter Transformer

The partial discharge detection technology (UHF) is specially used in YD-B Phase of ± 660kV converter trans- former pole I system, in connection with overheating failure problems. Through analysis by PRPD map to strengthen the monitoring for partial discharge defective of converter transformer, the continuous tracking for the running state of con- verter transformer can be achieved. Application results show that: the signal of partial discharge characteristics can be ef- fectively found inside the converter transformer through UHF Online Monitoring techniques, which has good sensitivity and Interference capability, providing guarantee for safe and stable running of power equipment.

Onsite Detection Technology and its Application for Electric Cable Partial Discharge

This paper introduces the electric cable partial discharge detection technology and elaborates pulse waveform characteristics of cable partial discharge, PD signal’s detection theory and basic method of cable PD source localization. On this basis, application examples of substation cable-site detection are given.

Research on Spectral Characteristics of GIS Partial Discharge Ultrasonic Signal

The traditional partial discharge detection method is difficult to be use in the scene charged detection because of its low frequency and vulnerable to test interference, need to power outages. Partial discharge detection technology has been international recognized in the application of the technology and research. This paper develop a system which can test the PD and manage the information. This method provide a precise and effective means of detection for charged equipment. Through the simulation of several typical defects, choose the best center frequency of ultrasound.

Partial discharge detection technology based on the fibre Bragg grating

ABSTRACTIn this study, the application conditions and influential factors of fibre Bragg grating sensors used for partial discharge detection are analysed by discussing basic mechanics of fibre Bragg grating sensors. A partial discharge detection system based on a fibre Bragg grating sensor is designed and used for detection of free metal particle discharge and suspended metal electrode discharge in oil. The detection results are compared with that of a system based on a piezoelectric sensor in comparison tests. The comparison includes the detection sensitivity, anti-vibration ability, and ability against strong electromagnetic interference in substations. The test results show that the system based on the fibre Bragg grating sensor can effectively detect typical discharges; its sensitivity is similar to that of the system based on the piezoelectric sensor. The fibre Bragg grating system is more easily interfered by vibrations, but has greater anti-electromagnetic interference ability than the piezoelectric system.

Simulation Analysis Based on Finite-Difference Time-Domain Algorithm for GIS Partial Discharge Detection

Gas insulated switchgear (GIS) has been widely used in global power grids currently. However, there are several disadvantages of GIS which will cause partial discharge (PD) in the insulation and then make GIS shut down. In this paper, the application of the ultra high frequency (UHF)method for partial discharge monitoring is discussed in detail, including the placement of the UHF sensors , detection system and the different characteristics of the different defects in the PD signals diagram are analyzed as well. Finally, some relevant conclusions are drawn based on Finite-Diffrenee Time-Domain algorithm (FDTD) for simulation of the electromagnetic waves by UHF PD detection technology.

Cross-equipment Evaluation of Partial Discharge Measurement and Diagnosis Techniques in Electric Power Apparatus for Transmission and Distribution

Partial discharge (PD) measurement allows detection of insulation defects in various electric power apparatus before an insulation failure occurs. It can also improve the reliability of the insulation performance of apparatus, and support rational and economical design, lifetime prediction, and nondestructive inspection. Historically speaking, PD detection methods have evolved in each category of apparatus and power cables. However, there does not seem to exist what we call universality in PD detection technology that is available to all kinds of power equipment. This article specifically describes features, similarities, and differences of partial discharge measurement and diagnosis technologies for electric power apparatus used in transmission and distribution. The main task of this article lies in not simply reviewing PD measurement and diagnosis techniques but trying a cross-equipment evaluation. First, this article deals with similarities and differences among partial discharge detection techniques for typical power apparatuses including gas insulated switchgear, oil-immersed transformers, and power cables. In particular electrical measurement technology and electromagnetic measurement technology are compared selectively. The second subject is to describe signal-processing technologies, and discuss similarities and differences among equipment in terms of noise removal, location identification, and foreign particle identification. Finally, judgment methods and judgment criteria for equipment diagnoses as a whole are analyzed and described. These discussions are expected to clarify the positioning of the partial discharge measurement technologies for various equipment among all electric power apparatus, and support technological development in the future.

Reliability of GIS EHV epoxy insulators: the need and prospects for more stringent acceptance criteria

Partial discharge (PD) scaling relationships, based on a recently developed theory, that allow prediction of PD magnitude in equivalent defects in different insulators for gas switchgear are presented. To maintain high levels of reliability, PD acceptance criteria of 0.5 to 1.0 pC are proposed for 550 kV insulators to obtain a standard of severity equivalent to that in existence at 138 kV. To achieve this level of testing, a number of techniques, including ultrawideband measurements, are proposed to improve present PD detection technology by at least two orders of magnitude. Sensitivities of better than 0.01 pC at up to 400 kV were routinely achieved in a factory-like environment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>