Yanjun Pang

Research on Judging Methods for Oil-Paper Capacitive Bushing Oil Lacking

The function of components and the theory of oil-paper capacitive bushing are introduced by analyzing its contracture, and the electric properties of insulation materials are instructed. The reasons and damages of lack of oil are proper illustrated, and the judging methods are offered. The distinguishing process of lack oil of bushing is illustrated by examples, and the accuracy and rationality of lack of oil finding by capacitive volume, dielectric loss angle, oil chromatogram analyzing and infrared ray test are demonstrated. Introduction The bushing is a kind of widespread used electrical equipment in power system. With a bushing the high voltage lead wire can pass through the earth body (wall, metal partition board and so on) or the oil box cover of electrical equipment to connect to other equipments. The transformer bushing and the wall bushing are used frequently for insulation and wire supporting in power system. The oil-paper capacitive bushing has been widely used in 66kV and upper voltage system because of its high utilizing factor of insulation, large specific capacitance, reasonable structure and small volume. In the long-term operation, the bushing have to bear the highest working voltage of long-term but also withstand all kinds of possible over-voltage, while the bushing itself due to dielectric (cable paper, transformer oil) gradual deterioration, moisture and partial discharges and other reasons, susceptible to various accidents. Ingress of moisture which will make the bushing oil lacking, resulting in insulation damp, will lead to partial discharge occurred within the bushing, causing the explosion [1]. Structure of oil-paper capacitive bushing Fig. 1 Structure of oil-paper capacitive bushing Oil-paper capacitive bushing consists of the copper conductive tube (pole), oil impregnated paper condenser cores, ceramic or compound hollow insulator and accessories [2]. The structure of 5th International Conference on Machinery, Materials and Computing Technology (ICMMCT 2017) Copyright

The Implementation of Load Forecasting Platform Based on Cloud Computing

As the rapid development of Chinas economy construction and scientific technology, the grid carrying load becomes higher and higher, and how to realize correct grid load forecasting technique becomes a current new smart grid studying hot spot. Without an exact calculation for the load, it can cause that the grid goes wrong in actual operation easily. Due to development and diffusion of cloud computing technology, it can realize load forecasting platform of Fushun smart grid by cloud computing technology at present. The thesis focuses on Fushun grid load forecasting, utilizes cloud computing technology to achieve implementation effects of grid load forecasting platform, and analyses and studies characters, main frame, primary technology, facing problems, related applications of Fushun grid load forecasting.

Diagnosis and Analysis of the Transformer Winding Deformation Fault

Together export transformer short-circuit accident analysis for a 66kV substation, analyze a variety of test methods 66kV transformer winding deformation, and the advantages and disadvantages of these test methods are discussed in detail, based on capacitance changes proposed transformer winding and with the frequency response method and short-circuit impedance, chromatographic analysis to accurately determine whether the transformer winding deformation methods. Introduction With the development of power system capacity is increasing in China, the short-circuit capacity increased, at the same time, the operation environment of the substation’s outlet and inlet line is not optimistic, all kinds of the over voltage occurs, due to external short-circuit with the transformer winding deformation, and it is the common faults during the operation of the transformer. Transformer suddenly occurs short-circuit fault, in transformer winding through the large short-circuit current, the short-circuit current interact with the leakage magnetic field generate large electric power force. Although the transient duration is very short, the transformer still is damaged. After the transformer is subjected to sudden short-circuit, if for the slight deformation is not found and repair in time, so after the transformer is subjected to repeated impact, the cumulative effect will cause the damage of the transformer. Therefore, in the process of operation, when the transformer occurs external short-circuit accident, how to quickly detect the existence of transformer winding deformation and deformation degree, it is important condition to guarantee the safe operation of the transformer[1-3]. On September 22nd 2012, there was construction accident of a 10kV cable dig occurred within a 66kV substation near the place, caused the No. 2 main transformer shutdown in 66kV substation , after sampled and did the chromatographic analysis of the transformer and there were no abnormal, the transformer was in operation. On September 28, 2012, due to construct the 10kV cable dig in rain caused by three-phase short-circuit accident, the No. 2 main transformer did differential protection action, caused the No. 2 main transformer in 66kV substation shutdown again. Called the protection record of the scene background computer and founded the No. 2 transformer was impact of the near outlet short-circuit current about 13kA ,the fault clearance time was 22ms.The following analysis of various testing methods about the 66kV main transformer winding deformation, and make a detailed discussion on the advantages and disadvantages of these test methods[4, 5]. Winding together with the bushing capacitance and dielectric loss test No. 2 main transformer type in 66kV substation is SZ11-31500/66; the rated voltage: 66±/8×1.25%/10.5kV, the rated current: 275.6/1732.1A, the factory time is in August,2011. After transformer factory, the winding capacitance is basically a certain. As long as the transformer has not received the short-circuit impact, even if there are effects of temperature, humidity condition, the capacitance change is very small. Suffered outlet short-circuit for the transformer, if the change of the winding capacitance is very big, the winding has deformation; the capacitance changes little, the transformer without deformation. In October 9, 2012,did the winding together with bushing capacitance and dielectric loss test for the transformer, the test data are shown in Table 1.