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Zhang J.,Ningxia Electrical Power Research Institute | Xu X.-Y.,China Electric Power Research Institute | Huang Y.-N.,Ningxia Electrical Power Research Institute | Cao Y.,Hohai University | Gu Y.-J.,Ningxia Electrical Power Research Institute
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2014

Ningxia's wind power and PV power both developed rapidly these years. The grid annual time sequence production simulation model containing renewable energy is established, whose target is to maximize energy conservation and emissions reduction benefits, the model considers wind and PV output, load characteristic, unit peak load regulation characteristic and thermal electricity couple characteristic of different heating units. Based on the model, Ningxia power grid renewable energy accommodation capability in 2015 is simulated, and optimized proportion of wind power and PV power considering renewable energy curtailment ratio and energy conservation and emissions reduction benefits is gained. The results provide guidance to the construction of wind and PV power, power system dispatching and policy making.

Chen D.,Hohai University | Yu Y.,Hohai University | Ju P.,Hohai University | Huang Y.,Ningxia Electrical Power Research Institute | Zhang S.,Ningxia Electrical Power Research Institute
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2014

As special power load exerts large impact on the stability of power system, the power quality and the safety of power equipment, its suitable modeling is essential in power system analysis. With the measured data of ferrosilicon load as an example, the self-varying characteristics of special power load are analyzed. Based on the UPI function of PSASP and user program, the time-varying current injection method is adopted in the modeling of special power load, which represents different electrical characteristics of load in the form of injection currents by circuit calculation. The model of the ferrosilicon load of a region in Ningxia is built according to its measured data, the comparison between simulative curves and measured data verifies the effectiveness and feasibility of the established model.

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.

Chen N.,Wuhan University | Wen X.-S.,Wuhan University | Lan L.,Wuhan University | Luo J.,Zhuzhou Electrical Power Bureau | Li Y.,Ningxia Electrical Power Research Institute
Gaodianya Jishu/High Voltage Engineering | Year: 2011

In order to investigate the power frequency electromagnetic field distribution of transmission line crossed in space, a three-dimensional electromagnetic field calculation model of three-phase cross-wire was established according to the catenary equation and considering conductor sag and tower. Based on the charge simulation method, the power frequency electrical field below the cross-wire was calculated, utilizing linear finite slant line charges to simulate the axial charge distribution in wire. Based on the Biot-Savart theorem, the power frequency magnetic field below the cross-wire was calculated by finite thin current-carrying wire model. Meanwhile, the influence law of crossing angle and line-phase on field distribution was discussed. The calculation results show that the electromagnetic field below the cross-wire decreases with the crossing angle getting larger, and the field distribution changes with line-phase altered; the maximum electrical field occurs near the projection of the same phase cross-wire intersection, and the maximum magnetic field occurs near the projection of the intersection of middle phase of the top wire and side phase of the lower wire. Besides, the wire at the bottom plays a shield wire role in electrical field, however, for magnetic field, the role is related with crossing angle. In the end, the electromagnetic field is surveyed on the spots for two typical crossed wires in YinChuan area, and the availability of the algorithm is validated.

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.

Liu H.T.,Ningxia Electrical Power Research Institute | Huang M.Y.,Ningxia Electrical Power Research Institute | Zhang Y.H.,Beijing Join Bright Digital Power Technology Co.
Advanced Materials Research | Year: 2014

According to the deficient situation of study in merging unit performance evaluation, this paper set up a comprehensive evaluation model for merging unit performance evaluation. Introduced triangular fuzzy number and determined the index weight through certain processing conversion, and set up a scientific system of performance indicators, and then selected normal distribution as the membership function. On this basis, this paper established a hierarchical and sub-aims comprehensive evaluation model. Finally, the model was applied for evaluating a merging unit performance. The evaluation result showed that the weight was effective and the fuzzy comprehensive evaluation model was simple and reliable. © (2014) Trans Tech Publications, Switzerland.

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.

Liu T.,China Electric Power Research Institute | Ye X.,China Electric Power Research Institute | Wu G.,China Electric Power Research Institute | Su Z.,China Electric Power Research Institute | And 3 more authors.
Dianwang Jishu/Power System Technology | Year: 2014

Along with large-scale grin-connection of wind farms, power dispatching department put forward a higher requirement on the active power control of the wind turbine and its participation in frequency regulation and peak load regulation. In allusion to the situation that wind turbines can only participate in automatic generation control (AGC) in the form of qualitative analysis due to nonexistence of the wind turbine model for the simulation of dynamic process in minutes level, an active power control model of wind turbine, which is suitable for medium- and long-term dynamic simulation, is proposed and its programming has been accomplished in the power grid whole process simulation program. In the proposed wind turbine model the continuous fluctuation of wind speed, the scheduled output and the real-time control commands of AGC are taken as the input, and by means of adjusting the pitch angle the power output of wind turbine is adjusted. The proposed wind turbine model can be used to simulate the impact of wind turbine output fluctuation on power grid, and the process of wind turbine participating the regulation and control of AGC can be dynamically simulated. Case study results show that the proposed wind turbine model can be used to simulate the response of wind power generating units under the control and regulation commands of AGC.

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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