The importance of establishment of the low-carbon power grid index system and its comprehensive evaluation model for the development of the low-carbon power grid is firstly discussed. Based on the concept of life cycl...
详细信息
With the constant expansion of power grid, a large number of security constraints have put tremendous challenges to the online economic dispatch. An efficient tool to eliminate the inactive constraints becomes necessa...
详细信息
With intermittent sources integrated into the power grid, power flows of the power grid are getting stochastic. Considering the uncertainty problem of DC power flow in the high voltage transmission system, this paper ...
详细信息
The development of UHV transmission technology brings longer transmission distance, higher towers and more complicated terrain along the transmission lines, which make the shunt performance of transmission line under ...
详细信息
ISBN:
(纸本)9781479935451
The development of UHV transmission technology brings longer transmission distance, higher towers and more complicated terrain along the transmission lines, which make the shunt performance of transmission line under lightning stroke more diversiform compared to conventional ones. This paper discusses the effects of factors, such as lightning current waveform, footing resistance, transmission line span etc., on the shunt coefficient of UHV DC transmission lines, which is of great significance for setting out lightning-proof measures as well as the location of lightning stroke point. It is referred that lightning current waveform especially its front time as well as tower footing resistance plays a significant role in determine of the tower shunt coefficient under lightning stroke. As the results indicates, the shunt coefficient of ground wire gets larger as the footing resistance increases while it decreases first and then increases as the front time of the lightning current waveform increases. The shunt coefficient of tower is just the opposite.
Space charge behavior of XLPE/SiO 2 nanocomposites with nanoparticle surface modification via titanate(TC) and vinylsilance(VI) coupling agents was investigated. SEM results clearly show that TC and VI coupling agent...
详细信息
ISBN:
(纸本)9781479927906
Space charge behavior of XLPE/SiO 2 nanocomposites with nanoparticle surface modification via titanate(TC) and vinylsilance(VI) coupling agents was investigated. SEM results clearly show that TC and VI coupling agents improved nanoparticle dispersion within XLPE matrix due to the increasing surface hydrophobicity of SiO 2 nanoparticles. Space charge measurements under high electric field revealed that SiO 2 nanoparticles could not effectively suppress the injection and movement of space charge until organic surface modification, which was believed due to more and deeper trap sites considering the better dispersion of SiO 2 nanoparticles.
Inter-turn short circuit of field windings is a common electrical fault of *** is an important method of investigating the fault and providing data support for fault ***,huge numbers of pole pairs and damper loops in ...
详细信息
Inter-turn short circuit of field windings is a common electrical fault of *** is an important method of investigating the fault and providing data support for fault ***,huge numbers of pole pairs and damper loops in large hydro-generators would lead to lengthy calculation time,hindering scientific research and engineering *** deal with this problem,we analyze a theoretical basis for a damper winding simplified model and then propose an equivalent treatment *** the analysis of steady-state current harmonic characteristics of generators with different stator winding configurations during the fault,the simplified models suitable for steady-state calculation are derived from two aspects,namely,additional rotor harmonic current frequency characteristics and the relationship of the amplitude as well as the phase of each branch current of the *** calculation and experimental results of the two simplified models are then compared to verify the models' correctness.A calculation example of the Three Gorges left bank VGS generator shows few deviations between the calculation results of the simplified model and the original ***,the calculation time using the simplified model is 1/1500 that using the original model,which provides a more effective tool for on-line fault ***,the sensitivity-verification application of the fault-monitoring scheme based on the stator steady-state unbalanced current RMS is *** result shows that the scheme can monitor two-turn short circuits of field windings in the Three Gorges generator and provide high sensitivity.
Very-fast transient overvoltage (VFTO)-related problems are raising growing concerns in China with the development of ultra-high voltage. The practice of fitting ferrite rings on gas-insulated switchgear busbars for V...
详细信息
power injection becomes stochastic due to large-scale wind power integration into power grid, which greatly challenges the traditional power grid. If the uncertainty is modelled using the interval number, the solution...
详细信息
Due to the power electronic devices in doubly fed induction generators (DFIG), it is very time consuming to simulate the electromagnetic transients of DFIG using its detailed model. Thus it is necessary to have approp...
详细信息
ISBN:
(纸本)9781849197588
Due to the power electronic devices in doubly fed induction generators (DFIG), it is very time consuming to simulate the electromagnetic transients of DFIG using its detailed model. Thus it is necessary to have appropriately simplified model of DFIG that maintains desirable accuracy. In this paper, the piecewise averaged model of PWM converters is introduced and applied to the modelling of DFIG. The proposed model divides the simulation time interval into switching periods and recalculates the averaged state equations of PWM converters in each switching cycle. In addition, a predictorcorrector based EMTP algorithm is designed to iteratively solve the model. Instead of treating switching events at the time points when they happen, the new algorithm solves all the switching instants in a switching cycle at the same time, which avoids frequency modification of the system conductance matrix and speeds up EMT simulations of DFIG. simulation results of a single-machine infinity bus system with a DFIG show that the proposed model and algorithm can achieve satisfactory accuracy and efficiency.
Regenerative compressed air energy storage (RCAES) system is a practical and efficient solution to large-scale integration of renewable energy problems faced by powersystems currently. Appropriately modeling of RCAES...
详细信息
Regenerative compressed air energy storage (RCAES) system is a practical and efficient solution to large-scale integration of renewable energy problems faced by powersystems currently. Appropriately modeling of RCAES system is critical to its practical application, whereas research in this area has been very limited. According to the energy storage and transformation process, a concise model of RCAES system applicable to power scheduling field is proposed. Then, a unit commitment model with RCAES system is formulated as a MILP problem which can be accurately solved with high computation efficiency by CPLEX. A modified IEEE 39 bus system is used to study the impacts of parameters of RCAES system on unit commitment and the effectiveness of the proposed model is then validated. Furthermore, the proposed model can also be employed to optimize key parameters of RCAES system, e.g. efficiency and capacity of each part in an integrated way.
暂无评论