On-line Partial Discharge Monitoring System Research Articles

On-Line Partial Discharge Monitoring System for Switchgears Based on the Detection of UHF Signals

Aiming at the phenomenon of partial discharge caused by the insulation fault of switchgears, an ultra-high frequency (UHF) partial discharge online monitoring system based on the Internet of Thing (IoT) is designed. The hardware of the system mainly consists of UHF sensors, signal conditioning circuits, and data acquisition circuits to realize the monitoring of the discharge signal. The monitoring data is uploaded to the cloud platform through the 4G DTU module, and the host computer software based on B/S architecture is designed on the server side, which can monitor the operation status of the switchgear anytime and anywhere. The experimental results show that the detection system is stable and reliable and can meet practical needs.

Digital Tools Approach Based On ‘Gerun’ And Online Partial Discharge Monitoring Project To Resolve Alternator’s Failure

There is no online monitoring system and digital tools to monitor generator gas turbine healthiness led to generator failure caused un-planned outages resulted power import and penalty chargers. Maintenance program for generator is based on time-based method. Since 2016 to 2020, Asset Team spent millions of ringgit Malaysia for generator rectification and incurred power import cost due to the failure. To overcome the tripping issues, Generator Health Monitoring System was initiated as a research/pilot project as tools to monitor healthiness of Gas Turbine Generator. This project was categorized as digital transformation initiative (Revolution 4.0) as to enable online monitoring & performing diagnostic & prescriptive. The initiative consisted of 2 main pillars which are Generator Rotor Unhealthiness Notification (GERUN) and Online Partial Discharge Monitoring System (PD ONLINE). The aim of this paper is to share the experience in monitoring, economical way, diagnosis, condition evaluation, and possibility of predicting the performance of the generator. The methodology of the Generator Healthiness is to monitor the real time performance of the generator during running condition through rotor thermal losses, ratio of excitation current over the real output power and stator partial discharge pattern. This real time monitoring can improve the maintenance strategy and planning. As a result, plant’s OEE can be increased, reduce the MTBF and more importantly the repair cost. The parameters have been introduced to prevent the generator sudden failure event and bridge the gap condition monitoring especially on the generator part. Arriving to the objective, this project was categorized as digital transformation initiative (Revolution 4.0) as to enable online monitoring & performing diagnostic & prescriptive. The initiative consisted of 2 main pillars which are Generator Rotor Unhealthiness Notification (GERUN) and Online Partial Discharge monitoring system (PD ONLINE) project. Diagnose & prescriptive and provide asset owners with insights on alternator’s health, subsequently prevent unforeseen failure in real time and prescribe operational mitigations to prolong alternator’s life. Recommends targeted test and maintenance (3rd level maintenance predictive) addressing the exact health issue of the alternator value creation & cost saving by eliminating tripping, scope reduction for major inspection, non-dependable on FSR, internal troubleshooting and etc. The system has been implemented across gas processing and utilities Petronas Gas Berhad for 14 units of gas turbine generator. In view of the success implementation, this digital tool will be duplicate to others Petronas Operating Unit.

The Positive Role of the Partial Discharge Monitoring System in the Partial Discharge Detection of GIS Equipment

When gas insulated metal enclosed switchgear and controlgear (GIS) has internal discharge, some faults are difficult to find during inspections due to the enclosed metal casing. This paper introduces the event of the floating potential discharge inside the GIS equipment of a 500kV substation found by GIS on-line monitoring system. Through on-site ultra-high frequency detection and precise positioning of the oscilloscope to determine the position of the discharge source at a certain switch, combined with the disassembly of the equipment, it is determined that the equipment defect is the discharge of the floating electrode of the switch fork.The results show that the on-line monitoring of GIS partial discharge has an important reference role in discovering the internal discharge of equipment during the test interval, and the monitoring and maintenance of GIS partial discharge on-line monitoring system should be strengthened in daily work.

Construction and Experimental Verification of Novel Online Partial Discharge Monitoring System Using Power Line Communication

In this research, we aim to construct a completely new partial discharge (PD) monitoring system that applies inexpensive power line communication (PLC). We have proposed a PD detection method and monitoring system (PDMS-PLC) on the basis of PLC signal transfer rare is affected by an error due to disturbance. An attempt is made to identify PD source from the quadrant dependence of information transmission rate (hereinafter referred to PHY rate [Mbps]) by selecting a pair of quadrants of applied voltage phase; i.e. 1st and 3rd quadrants, or 2nd and 4th ones. It was found that the PHY (Abbreviation for the lowest physical layer in the OSI (open systems interconnection) hierarchical model.) rate number distribution reflects the PD characteristics obtained by the phase resolved PD (PRPD) pattern. Environmental noise level is also measured at an actual substation using PDMS-PLC. Consequently, the applicability of PDMS-PLC to PD signal detection and defect type identification is suggested.

Flexible Sensor Array Based on Transient Earth Voltage for Online Partial Discharge Monitoring of Cable Termination.

Cable termination is a weak point in an underground cable system. The transient earth voltage (TEV) method is an effective and nonintrusive method for estimating the insulation condition of cable termination. However, the practical application of TEV detection is mainly focused on switchgears, generators, and transformers with a flat and conductive shell. A flexible sensor array based on the TEV method is presented for online partial discharge (OLPD) monitoring of the cable termination. Each sensing element is designed with a dual-capacitor structure made of flexible polymer material to obtain better and more stable sensitivity. Based on the electromagnetic (EM) wave propagation theory, the partial discharge (PD) propagation model in the cable termination is built to analyze and verify the rationality and validity of the sensor unit. Some influencing factors are discussed regarding the response characteristics of sensors. Finally, the performance of the sensor array is verified by simulations and experiments. Besides, an OLPD monitoring system is introduced. The monitoring system is composed of the on-site monitoring device and the remote monitoring host. The two parts of the system exchange the data through wireless networks using a wireless communication module. The experiment results show that the monitoring device could supply the PD condition monitoring demand for cable termination.

On-Line Partial Discharge Monitoring System for Power Transformers Based on the Simultaneous Detection of High Frequency, Ultra-High Frequency, and Acoustic Emission Signals

The article presents a novel on-line partial discharge (PD) monitoring system for power transformers, whose functioning is based on the simultaneous use of three unconventional methods of PD detection: high-frequency (HF), ultra-high frequency (UHF), and acoustic emission (AE). It is the first monitoring system equipped in an active dielectric window (ADW), which is a combined ultrasonic and electromagnetic PD sensor. The article discusses in detail the process of designing and building individual modules of hardware and software layers of the system, wherein the most attention was paid to the PD sensors, i.e., meandered planar inverted-F antenna (MPIFA), high-frequency current transformer (HFCT), and active dielectric window with ultrasonic transducer, which were optimized for detection of PDs occurring in oil-paper insulation. The prototype of the hybrid monitoring system was first checked on a 330 MVA large power transformer during the induced voltage test with partial discharge measurement (IVPD). Next, it was installed on a 31.5 MVA substation power transformer and integrated according to the standard IEC 61850 with SCADA (Supervisory Control and Data Acquisition) system registering voltage, active power, and oil temperature of the monitored unit. The obtained results showed high sensitivity of the manufactured PD sensors as well as the advantages of the simultaneous use of three techniques of PD detection and the possibility of discharge parameter correlation with other power transformer parameters.

Pilot implementation of the on-line partial discharge monitoring system for heads of the high voltage cable lines

Pilot implementation of the on-line partial discharge monitoring system for heads of the high voltage cable lines

Development of smart online partial discharge monitoring system for medium voltage power cable

This paper presents, the development of smart online partial discharge (PD) monitoring system for medium voltage (MV) underground power cable. PD monitoring is the highly efficient tool to monitor insulation degradation for high voltage (HV) equipment in order to avoid failures or breakdown. Selection of improved technology and performance of PD detection sensor, effective measurement technique and smart user friendly of graphical user interface (GUI) system are contributed towards the development of efficient monitoring system. This paper addresses three main aspects which are needed in completing the monitoring system. They are, the use of Rogowski coil (RC) as detection sensor, processing unit using Alterra board and integrated with GUI PD monitoring system for underground cable using LabVIEW. The monitoring system is compared to the conventional method with the PD signal used is measured from the real on-site measurement in order to analyse its performance. The analysis is performed in MATLAB and LabVIEW software’s environment and the maximum peak of PD signal is enabled to view using GUI which complete with the location information of PD source. Furthermore, this paper has contributed to solve the problem in selection the simplified and practical approach for PD sensor and monitoring system. In the perspective of automated condition monitoring, this smart online PD monitoring system provides a complete solution towards latest industrial revolutions

The Development of Mobile On-line Partial Discharge Monitoring System of XLPE Cable

The existing on-line monitoring systems of cable are poor in mobility, cost performance and networking mode. Aiming at these deficiencies, a mobile on-line partial discharge monitoring system of XLPE cable is designed and developed in this paper. Besides the analysis of partial discharge pulse and diagnosis for cable insulation, the system features on flexible networking modes. The paper describes the hardware theory, development process details and significant parameters. And the architecture and interface of the system’s software are also demonstrated. A series of test and installation proves that, this is a flexible, stable, reliable system which can satisfy the requirement on on-line partial discharge monitoring of XLPE cable.

Online Partial Discharge Condition Monitoring of Complete Networks: Challenges and Solutions Explained through Case Studies for the Pulp and Paper Industry

Unplanned outages within the paper industry lead to significant costs to operators. To reduce unplanned outages and losses, condition monitoring (CM) techniques can be implemented to determine asset health and help target maintenance to where it is required most. The challenges faced by the paper industry to implement condition-based maintenance (CBM) on their medium-voltage (MV) and high-voltage (HV) networks and solutions for online partial discharge (OLPD) monitoring are due to the range and number of assets present and the geographical spread coupled with problems of retrofitting the technology on pre-existing plants. The implementation of OLPD testing or monitoring can vary based on several factors: network topology, connected assets, switchboard type, and the owner's budget and desired local engineer involvement. This article discusses different approaches to implementing an OLPD test program, ranging from simple handheld survey units to complete network monitoring. Its focus is on case studies of the deployment of OLPD testing and monitoring solutions at several U.S. paper sites. The case studies present diagnostic testing of unshielded MV cable at one paper mill up to full permanent OLPD monitoring systems at two others.

On-line partial discharge monitoring system for underground MV cables – Part II: Detection and location

Condition based maintenance constitutes a useful tool towards upgrading aging infrastructure in the context of asset management in smart grids. Towards that aim, on-line partial discharge (PD-OL) monitoring systems can provide useful information regarding insulation degradation, that can be used to prevent destructive faults. In this study, a set of novel algorithms is proposed for utilization in such a system. More specifically, an enhanced approach is proposed to denoise partial discharge (PD) associated measurements, by the utilization of the discrete wavelet transform (DWT). Moreover, an overall process is presented for the efficient detection of peaks in denoised signals, and the respective calculation of the PD apparent charge. Furthermore, algorithms are proposed for the detection and location of PDs in practical applications, taking also into account possible pulse reflections, and disregarding the corresponding false positive detections. All proposed methods are rigorously tested, and the respective results are presented.

Research and Design of Cable Partial Discharge Online Monitoring Technology Based on GPS Clock Wireless Synchronization

A prototype of cable partial discharge online monitoring system was presented in this paper, including partial discharge sensor, partial discharge collector, GPS wireless synchronization system, centralized monitoring host and operation software. Real-time cable partial discharge monitoring data transmitted wirelessly, analyzed by platform software, and output information of time domain waveform, frequency waveform, discharge quantity, PRPD spectra of discharge number-discharge quantity-power frequency phase, locating information of partial discharge, history record and query of partial record and alarm severity of partial discharge.

Research on Measurement and Evaluation of Ultra High Frequency Partial Discharge Monitoring Device

In order to evaluate the partial discharge Ultra High Frequency (UHF) detection device, the author conducted a laboratory simulation experiment on UHF Partial Discharge (PD) online monitoring system. The UHF signal is simulated by the pulse signal generated by the ns steep pulse generator. By comparing the characteristics of the generated UHF signal with the spectral features detected by the UHF partial discharge on-line monitoring system, the detection capability, pattern recognition ability, and anti-jamming capability of the UHF partial discharge on-line monitoring system are measured and evaluated. Through the research on the testing and evaluation of power equipment, it can ensure the normal operation of the partial discharge online monitoring system.

GIS UHF Partial Discharge On-line Monitoring Device Evaluation

The Ultra-high Frequency (UHF) partial discharge on-line monitoring system device is widely used in gas insulated substations (GIS), and has become one of the important detection methods for partial discharge of GIS. However, due to the lack of uniform standards within the industry, the equipment produced by the manufacturers is uneven, resulting in the performance evaluation problems of the UHF online monitoring device in the purchase and acceptance process. For this question, this paper proposes a measurement method, which has two parts: UHF sensor evaluation and complete device evaluation.A set of evaluation methods was established by using a signal simulation test method and a simulated fault evaluation method, and a more comprehensive understanding of the GIS UHF partial discharge on-line monitoring device were proposed.

Field Applications of Ultra High Frequency Techniques for Defect Detection in GIS

The reliable and stable operation of power apparatus is important for the development of GIS. It is important to utilize condition monitoring technologies and anticipate possible failures in advance. Many papers have been published about the partial discharge detection with UHF or X-ray in laboratory, but seldom in field application. Thus, many engineers at project sites are not familiar with the current professional diagnosis techniques. Recently, during the GIS routine data analysis obtained by partial discharge online monitoring system, it was found that the UHF monitoring signals’ developing trend of the 220 kV GIS No. 2 high-voltage side of transformer in phase C at an actual station was abnormal and needed further detection. In order to precisely investigate the problem and then guide the operation and maintenance activities, a series of professional diagnoses were conducted. Three new types of partial discharge detection and positioning methods were applied for accuracy, including UHF partial discharge detection based on multi-stage amplified signal demodulation and multiple weighted averages processing; the partial discharge detection based on the signal radiation hole of insulation disk at the ground connection; and the positioning method based on UHF-SHF. After a series of troubleshooting works, the partial discharge defects have been diagnosed, and the case can be referred in the field monitoring of GIS.

Fractal‐based autonomous partial discharge pattern recognition method for MV motors

On-line partial discharge (PD) monitoring is being increasingly adopted to improve the asset management and maintenance of medium-voltage (MV) motors. This study presents a novel method for autonomous analysis and classification of motor PD patterns in situations where a phase-reference voltage waveform is not available. The main contributions include a polar PD (PPD) pattern and a fractal theory-based autonomous PD recognition method. PPD pattern that is applied to convert the traditional phase-resolved PD pattern into a circular form addresses the lack of phase information in on-line PD monitoring system. The fractal theory is then presented in detail to address the task of discrimination of 6 kinds of single source and 15 kinds of multi-source PD patterns related to motors, as outlined in IEC 60034. The classification of known and unknown defects is calculated by a method known as centre score. Validation of the proposed method is demonstrated using data from laboratory experiments on three typical PD geometries. This study also discusses the application of the proposed techniques with 24 sets of on-site PD measurement data from 4 motors in 2 nuclear power stations. The results show that the proposed method performs effectively in recognising not only the single-source PD but also multi-source PDs.

Experience With Online Partial-Discharge Measurement in High-Voltage Inverter-Fed Motors

Partial-discharge (PD) testing has long been an important tool for assessing the condition of the high-voltage insulation in motor and generator stator windings. In the past several years, many motors have been powered from inverters, which facilitate variable-speed motor operation. The most common drive used today is the voltage-source pulse-width modulation (VS-PWM) type. VS-PWM drives rated up to 13.8 kV are becoming more common in natural gas processing plants, as well as in other petrochemical facilities. Such drives generate high-voltage impulses in the kilovolt range with rise times in the submicrosecond range. These impulses are a form of severe electrical interference that can make difficult the online detection of PD (with magnitudes 1000 times smaller) due to the overlapping frequency content in PD and in the impulses. Thus, PD detection on medium-voltage VS-PWM systems has been a challenge in spite of the serious stator winding insulation aging that such drives may cause to these motors. This paper discusses the stator winding failure mechanisms that produce PD, including the insulation problems that VS-PWM drives can accelerate. A research project that lasted several years is reviewed. This project culminated in a prototype online PD monitoring system suitable for motors fed by VS-PWM drives.

Improving asset management with online partial discharge monitoring of ring main units and secondary substations

Traditional permanently installed online partial discharge (PD) monitoring systems are highly advanced systems, running high-resolution acquisition electronics with processor heavy software analysis to separate PD signals from background noise interference. These systems are cost-effective for primary/grid sites, where the cost of a single failure is often much higher than the cost of the monitoring system. In a secondary substation, however, this is not a viable solution technically or financially and alternative asset management solutions must be considered. There has been a technological void for mid-range monitoring solutions. However, recent developments in more industrialised and fan-less computers offer the required processing power and technological advancement, enabling the development of PD monitoring systems which can still effectively differentiate PD and noise and operate in the harsh conditions of a secondary substation. Additionally, powerful microprocessors are being manufactured in a such high volumes, that the price of the units are reaching the level where they can be incorporated into a PD monitoring system which is cost-effective for installation over the large asset base of a secondary network whilst ensuring reliable outputs of asset condition. Therefore, offering a solution for monitoring of the largest part of a distribution network which previously went unmonitored.

Extending the Functionality of On-line PD Monitoring Equipment for MV Power Cables

An on-line partial discharge (PD) monitoring and location system for medium voltage cable circuits was developed previously. This paper explores ways to extend its range of application. The extension includes PD location method by time domain reflectometry (TDR) when reflections are not easily identifiable. The functionality of the PD monitoring equipment can also be widened by sensing other quantities related to the condition of the cable insulation using the same device. Dynamic cable temperature monitoring can be achieved by recording variation in the high frequency signal propagation velocity along the cable. Water ingress in paper-insulated lead-covered (PILC) cable decreases the cable’s characteristic impedance while it increases the permittivity of the insulation. It can be observed by changes in the reflection pattern from the cable or by a lowered propagation velocity. Instead of recording reflection patterns in time domain, a frequency domain approach based on an impedance scan is investigated to be applied for cables in service.

SDMF based interference rejection and PD interpretation for simulated defects in HV cable diagnostics

Partial Discharge (PD) in cable systems causes deterioration and failure, identifying the presence of PD is crucial to Asset Management. This paper presents methods for interference signals rejection and for PD interpretation for five types of artificial defect in 11 kV ethylene-propylene rubber (EPR) cable. Firstly, the physical parameters of the artificial defects used for PD signal generation are introduced. Thereafter, the sample stress regime, PD testing and detection systems, including IEC 60270 measurement system and High Frequency Current Transformer (HFCT), are outlined. Following on, a novel Synchronous Detection and Multi-information Fusion (SDMF) based signal identification method is developed, to separate PD and interference signals within raw data. Finally, a comparative PD analysis of two detection systems is carried out and several characteristics of insulation related PD signals of EPR cables are reported. The SDMF based data pre-processing and the comparative PD activity analysis contribute to improvement of PD pattern recognition and assist in on-line PD monitoring systems.