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Jian Hao - IEEE Xplore Author Profile

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The thermal oxidative aging of cross-linked polyethylene (XLPE) during cable operation is a primary factor leading to changes in its mechanical properties. Notably, these properties exhibit an initial increase followed by a decrease as aging progresses. In this study, molecular models of silane-cross-linked polyethylene (Si-XLPE) and peroxide-cross-linked polyethylene (p-XLPE) were constructed to ...Show More
High-voltage (HV) crosslinked polyethylene (XLPE) cables are subjected to electrothermal stress gradients during service, which often leads to nonuniform degradation within insulation systems, significantly affecting their endurance, resilience, and overall lifetime. This article presents a comprehensive study of dielectric mechanisms and health state estimation of XLPE insulation under nonuniform...Show More
Temperature rise characteristics is an important characteristic that affects the working state of the vacuum interrupter, understanding and mastering its temperature distribution and temperature rise law and its hot spot temperature monitoring research, to avoid the interrupter due to thermal faults caused by the performance of the destruction of the practical significance of the engineering has a...Show More
Gas insulated switchgear (GIS) mechanical defects are the main cause of equipment failure, and accurate and efficient identification of defect types is crucial to ensure the safety of equipment operation. Aiming at the high complexity of GIS mechanical defect signals, which is difficult to select feature parameters and depends on expert experience for a long time, this paper proposed a GIS mechani...Show More
High voltage, large capacity, long-distance offshore wind power access requires Extra-high-voltage (EHV) submarine cable with strong insulation performance to transmit power. In order to improve the safety and reliability of EHV AC submarine cable, the EHV 500 kV cross-linked polyethylene (XLPE) submarine cable is taken as the research object, and the “Electromagnetic- Thermal-Flow” multi physical...Show More
The resin-impregnated paper valve-side bushing of the UHV converter is subjected to AC/DC compound voltage in operation, and its electro-thermal characteristics are affected by operation factors. Therefore, it is necessary to analyze the distribution characteristics of the electric field and temperature field under different operation factor. An electro-thermal coupling simulation model is establi...Show More
Employing simulation as a strategic approach to enhance the thermal performance of insulating oils presents a scientifically grounded and efficient methodology. The thermal stability of insulating oils plays a crucial role in ensuring the safe and reliable functioning of transformers. This research employs molecular dynamics theory to assess the variations and discrepancies in microscopic thermal ...Show More
During the operation of transformers, the oil-paper insulation system is susceptible to lightning impulse voltage. Investigating the lightning impulse discharge characteristics of a multi-component mixed insulation oil-paper composite system can support the design of interturn and intercake insulation pad structures in transformers. This paper examines the lightning impulse discharge characteristi...Show More
A non-uniform aging pattern inside insulation systems is a significant contributor to the degradation of high-voltage (HV) power equipment. Therefore, this article presents a comprehensive investigation into the effects of non-uniform aging patterns on broadband dielectric properties of polymer insulation, with a focus on XLPE power cables, aiming to provide a deeper understanding of these effects...Show More
The main causes of harmonic distortion in new power systems are high percentage renewable energy grid connections and high percentage power electronic equipment access. These factors pose a serious threat to the ultra-high voltage converter transformers’ ability to perform as oil-paper insulation, and little research has been done on the failure law of oil-paper insulation that takes the effects o...Show More
Ultra-high voltage (UHV) converter transformers are located at the core of alternating current (AC) and direct current (DC) changes. During operation, it is subject to a large number of harmonic currents with frequencies higher than the fundamental frequency. A series of harmonic currents will cause different degrees of vibration and deformation of the windings, threatening the normal operation of...Show More
Insulation defects affect the electric field and temperature distribution in the valve-side bushing during operation. It is necessary to analyze the influence of defects on the electric field and temperature distribution, which contributes to the subsequent assessment of the operating condition and the risk warning. An electro-thermal coupling simulation model is established based on a valve-side ...Show More
In the context of green energy transition in extra-high-voltage (EHV) power transmission, EHV polymeric cable connecting power generation and loads is a key power asset in the large-ampacity power system. However, harsh operating environments brought from renewable energy and power electronics will create a huge challenge to EHV cable insulation reliability. Notably, EHV cables with enough insulat...Show More
The holistic and non-destructive insulation reliability assessment of high-voltage (HV) cable assets is continuously paid more attention to supporting the resilience, safety, reliability, and availability of power systems. Clear dynamic physical mechanisms of HV cable assets will be visualized using broadband dielectric spectroscopy (BDS). Therefore, this paper aims to present some crucial observa...Show More
The primary sources of harmonic distortion in the new power system are a high percentage of access to power electronic equipment and a high percentage of renewable energy grid connections. These factors pose a major risk to the UHV converter transformer oil-paper insulation performance. However, the influence law of harmonic voltage on the electric field distribution characteristics (EFDC) of oil-...Show More
The establishment of oil-paper insulation composite system health state assessment model is of great significance for the protection of transformer safety, for the current oil-paper insulation state assessment model of a single characteristic quantity and state assessment method is too abstract and so on, this paper is based on the partial discharge maximum discharge per unit, average discharge pe...Show More
As one of the widely used equipment in the power network, the safe operation of oil-immersed transformers is a basic element of the safety work of the power network. Due to the transformer daily load fluctuation changes drastically, in normal operation, with the change of load rate transformer temperature fluctuates within a certain range. In order to grasp the transformer hot spot dynamic tempera...Show More
This paper is devoted to the use of circuit modelling to analyze the evolution mechanism of dielectric properties of 500 kV Extra-High-Voltage (EHV) submarine cables at different high field strengths, and to promote the application of high-field broadband dielectric spectroscopy in the condition inspection of power equipment. Taking new and aging submarine cables as analysis cases, based on extend...Show More
The ultra-high voltage (UHV) converter transformers are subjected to a large number of harmonic currents with frequencies higher than the fundamental frequency in the course of operation. This study formulates a dual-dimensional simulation framework for the converter transformer, predicated on an integrated theory of multiple physical fields, including electrical, magnetic, thermal, and mechanical...Show More
Epoxy (EP) resins find widespread application in power electronic (PE) applications characterized by multifrequency electrical stresses. Transient thermal overloads are also not uncommon due to, for example, short circuits in the external circuit. This article investigates the influence of various temperatures on broadband dielectric properties of EP insulation, above and below the glass transitio...Show More
Oil-paper insulation is the “heart” of power transformer, and frequency-domain spectroscopy (FDS) is an efficient method to evaluate the insulation state of it. Nevertheless, traditional FDS test voltage is still at 200 V, and the insulation characteristics of FDS at high voltage (HV) levels are worth exploring. Therefore, this article studies the FDS characteristics of oil-paper insulation at var...Show More
Use of traditional mineral oil (MO) as a liquid insulation in transformers has spanned more than 130 years. However, MO has poor heat resistance, a low ignition point, and is a non-renewable resource, which does not meet development requirements for high-performance and environmentally friendly insulation oil. Consequently, researchers have explored alternatives such as natural ester (NE) and synt...Show More
Here, the lightning impulse breakdown characteristics of mineral oil-impregnated paper (MO-P) (pressboard) and three-element mixed insulation oil (TEMO)-impregnated paper were tested. Molecular simulation was used to analyze the difference in lightning impulse breakdown characteristics of the two oil-impregnated papers at the atomic scale. The results show that when the thickness of the insulation...Show More
The breakdown voltage (BVE) of insulation oil-paper system is crucial to the steady operation of transformer. In this paper, the voltage and current waveform, BVE, discharge development time of mineral oil-paper system (MO-P) and three-element mixed insulation oil-paper system (TEMO-P) at gap lengths of 0, 5, 10 and 15 mm, as well as the morphologies of oil-impregnating paperboard are studied. The...Show More
The breakdown of insulating oil under the lightning impulse is crucial for oil-immersed transformers. Lightning breakdown in insulating oil is typically explained by the streamer theory which is related to the ionization properties of molecules. Therefore, Density Functional Theory (DFT) was used to simulate the ionization potential (IP) of oil molecules, and the finite element method (FEM) and ex...Show More