Ningxia Electrical Power Research Institute

Yinchuan, China

Ningxia Electrical Power Research Institute

Yinchuan, China
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Tsinghua University and Ningxia Electrical Power Research Institute | Date: 2016-12-22

Disclosed is a method for repairing an electrically erosive pot hole on a surface of a liquid silicone rubber (LSR) shed, including the following steps: using RTV anti-pollution flashover paint as a first coating, and coating the RTV anti-pollution flashover paint on a surface of an electrically erosive pot hole to make the surface of the pot hole smooth; using a mono-component RTV repair adhesive as a second coating to fill the electrically erosive pot hole, so as to fill and level up the electrically erosive pot hole, and the mono-component RTV repair adhesive is closely bonded to the first coating; and using the RTV anti-pollution flashover paint as a third coating, and coating the RTV anti-pollution flashover paint on the second coating. The method enables the appearance and performance of an LSR shed on which electrical erosion occurs to be effectively recovered.

Che B.,Ningxia Electrical Power Research Institute | Yu R.,China Electric Power Research Institute | Dang D.,Ningxia Electrical Power Research Institute | Wang X.,China Electric Power Research Institute
IOP Conference Series: Materials Science and Engineering | Year: 2017

Distributed Generation (DG) integrating to the network would cause the harmonic pollution which would cause damages on electrical devices and affect the normal operation of power system. On the other hand, due to the randomness of the wind and solar irradiation, the output of DG is random, too, which leads to an uncertainty of the harmonic generated by the DG. Thus, probabilistic methods are needed to analyse the impacts of the DG integration. In this work we studied the harmonic voltage probabilistic distribution and the harmonic distortion in distributed network after the distributed photovoltaic (DPV) system integrating in different weather conditions, mainly the sunny day, cloudy day, rainy day and the snowy day. The probabilistic distribution function of the DPV output power in different typical weather conditions could be acquired via the parameter identification method of maximum likelihood estimation. The Monte-Carlo simulation method was adopted to calculate the probabilistic distribution of harmonic voltage content at different frequency orders as well as the harmonic distortion (THD) in typical weather conditions. The case study was based on the IEEE33 system and the results of harmonic voltage content probabilistic distribution as well as THD in typical weather conditions were compared. © Published under licence by IOP Publishing Ltd.

Geng T.,State Grid Corporation of China | Xiang L.,State Grid Corporation of China | Ding M.,State Grid Corporation of China | Li F.,Ningxia Electrical Power Research Institute
MATEC Web of Conferences | Year: 2017

The evolution of the energy markets has been accelerating the use of distributed energy resources (DERs) all over the world. Virtual power plant (VPP) is a new method to management this increasing two-way complexity. In this paper, a bidding model for a VPP via robust optimization in the uncertain environment of the electricity market is presented. The flexible feature embedded in the model with respect to solution accuracy and computation burden would be advantageous to the VPP. Results of a case study are provided to show the applicability of the proposed bidding model. © The Authors, published by EDP Sciences, 2017.

Ding Y.,University of Sichuan | Liu T.,University of Sichuan | Gao F.,Ningxia Electrical Power Research Institute | Li X.,University of Sichuan
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2017

The reduced order power system models and relevant oscillation frequencies were identified by the total least squares (TLS)-estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm. Firstly, using Butterworth band-pass filter to decompose oscillation frequencies into different channels based on system oscillation modes. Thereafter, the multi-channel HVDC supplementary damping controller was designed by the multi-stage LQR method and configured with the state observer by the Ackermann formula. It included one low frequency oscillation channel and two sub-synchronous oscillation channels, which worked separately. The designed multi-channel HVDC supplementary damping controller provided damping for different oscillation modes to suppress low frequency oscillation and sub-synchronous oscillation. The proposed control strategy was demonstrated detailedly in a realistic HVDC system model built in PSCAD. Compared with the multi-stage linear quadratic regulator (LQR) method, LQR method and PI method, the simulation results in power systems computer aided design (PSCAD) have verified the effectiveness and robustness of the designed controller. The multi-stage LQR method has the certain significance for the practical application. © 2017, The editorial office of Transaction of China Electrotechnical Society. All right reserved.

Ma Z.,Tsinghua University | Liu F.,Tsinghua University | Shen C.,Tsinghua University | Zhang J.,Ningxia Electrical Power Research Institute | Gao F.,Ningxia Electrical Power Research Institute
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2017

As the second part of this two-part paper, this part focused on the factors that have impacts on the results obtained by the modified PageRank algorithm for rapid identification of vulnerable lines in power grid. Firstly, based on the principle of the algorithm introduced in the first part of this two-part paper, the influence of model parameters on the performance of algorithm was discussed, and the reasonable range of model parameters was given. Secondly, cascading failure simulation (CFS) based on DC OPA model was used to verify the accuracy of the proposed approach, and a difference indicator was put forward to quantify the differences in the results obtained by CFS and the presented method. The case studies were carried out respectively on the IEEE 118-bus and the IEEE 39-bus test system to demonstrate the validity and effectiveness of the proposed method. © 2017 Chin. Soc. for Elec. Eng.

Lan L.,Wuhan University | Ai S.-G.,Ningxia Electrical Power Research Institute | Huang Y.-N.,Ningxia Electrical Power Research Institute | Wang J.-Q.,Wuhan University | Wen X.-S.,Wuhan University
Gaodianya Jishu/High Voltage Engineering | Year: 2010

In double-circuit line on the same tower, three phases are unbalanced due to three-phase asymmetric parameters of each circuit and electromagnetic coupling between two circuits, which may endanger power equipment. Therefore, it is of great significance to calculate the unbalance degree and to analyze its influential factors of double-circuit transmission line. The unbalanced currents in Ningxia northern 220 kV power gird are large. Taking Ningxia northern 220 kV power gird as an example, we use ATP to build models for the ring network and to calculate the unbalanced currents of transmission lines based on practical power flow distribution, and compare the simulation results with measured data. The model includes the electromagnetic coupling between parallel lines and the topology of the ring network, which can simulate the real power grid effectively. The unbalanced currents under various operation conditions are obtained, consequently, the way to limit the current unbalance could be analyzed. The simulation results are in good agreement with the field data, and show that, by rationally adjusting the phase-order arrangement way of double-circuits transmission lines at the outlet of substation, the current unbalance in Ningxia northern 220 kV power grid can be effectively decreased.

Yan Z.H.,Ningxia Electrical Power Research Institute | Ren X.,Xi'an Jiaotong University | Ren H.,Xi'an Jiaotong University | Ding W.D.,Xi'an Jiaotong University
Applied Mechanics and Materials | Year: 2013

On-site experience suggests the possibility of condensation of the moisture in Current transformers (CTs) which is impossible theoretically if temperature distribution in the CT is uniform. In order to study the temperature distribution in a typical CT, finite element analysis software (COMSOL Multiphysics) is used to obtain the temperature distribution of the outer surface and inside of SF6 in CT in different ambient temperatures (20 °C to -10 °C). Besides, experiments are conducted to obtain the temperature of different positions on the CT surface that correspond to conductor, shell, spacer and porcelain bushing that are inside the CT with different ambient temperature. Both simulation and experiments show that temperature distribution in the CT is non-uniform, and the closer the part is to the conductor, the higher the temperature. Furthermore, maximum temperature difference remains about 35 °C in both simulation and experiments with different ambient temperatures from 20 °C to -10 °C. © (2013) Trans Tech Publications, Switzerland.

An Y.,Wuhan University | Wen X.,Wuhan University | Zhang T.,Qingdao Power Supply Company | Ma K.,Ningxia Electrical Power Research Institute | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2013

To ensure the safety of substation expanding and new shunt reactor operation, we researched the overvoltage of shunt reactor during switching-on process by theoretical analysis, tests and simulations, and theoretically analyzed the reasons of the overvoltage from two aspects, namely, mechanism of transient prebreakdown of SF6 breaker and reflection and refraction of wave. Moreover, we established a SF6 breaker prebreakdown model in ATP-EMTP to simulate the field tests. Tests and simulation results showed that the specific overvoltage on the reactor during process of switching-on could reach 4.0. However, simulation results showed that, with resistance and capacitance absorption equipment, the specific overvoltage could be decreased to 1.68 in the same condition. Simulation results indicated that the absorption equipment could be an effective measure for overvoltage limitation, which not only decreased the systematic overvoltage but also restrained systematic harmonics. The pre-breakdown phenomenon introduced in this paper could be referred for protection of shunt reactor operation in substations.

Chen N.,Hubei Engineering University | Wen X.,Hubei Engineering University | Liu B.,Hubei Electric Power Company | Lan L.,Hubei Engineering University | Li Y.,Ningxia Electrical Power Research Institute
Dianwang Jishu/Power System Technology | Year: 2011

To calculate power frequency electric and magnetic fields (PFEMF) generated by high voltage transmission line or space-crossing transmission lines accurately, based on charge simulation method (CSM) and Biot-Savart theorem, a universal model to calculate three dimensional PFEMF is built according to catenary equation, then the distribution of PFEMF under ordinary 330 kV double circuit transmission line on the same tower and that under the crossing transmission lines are calculated and measured. Calculation and measurement results show that as for the transverse distribution of PFEMF along the measured points perpendicular to the midspan, the results calculated by three-dimensional model under the calculation height of the conductor that is chosen as the minimum height above ground are very close to those calculated by two-dimensional model and are close to the measured results as well; at the projection beneath the crossing point of crossing transmission lines, the calculation results of PFEMF are close to the measured results, thus the effectiveness of the proposed calculation model of crossing transmission lines is verified. The causes leading to the error between the calculation results of PFEMF and its measured results are analyzed, and related factors influencing the calculation results by three-dimensional calculation model are emphatically discussed, and the reasonable number of divided conductor segments is given.

Li X.,Ningxia Electrical Power Research Institute
Gaoya Dianqi/High Voltage Apparatus | Year: 2015

To investigate the inducement of porcelain bushing explosion of an SF6 insulated current transformer in operation, the finite element method is used to simulate the temperature field in the SF6 current transformer. Simulation and experimental results show that the temperature distribution is uneven in the SF6 current transformer, and the nearer the position to the conductor, the higher the temperature difference. The maximum temperature difference maintains about 35℃. ©, 2014, Xi'an High Voltage Apparatus Research Institute. All right reserved.

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