车用功率分流式液压混合动力系统特性研究

基于液压机械传动,提出了一种分速汇矩式液压混合动力传动系统.通过对系统的布置结构、主要组成元件描述及工作机理分析,研究典型工况功率流特性,提出了可行的再生制动方案.分析了再生制动和辅助驱动工况的工作特性.并结合计算机仿真,基于一定城市运行工况分析了系统的再生制动效能和辅助驱动性能.结果表明,液压混合动力技术改善了配备液...     

基于联合模型的短期电力负荷预测方法

为了准确预测电力负荷并提高电力系统调节和调度的灵活性、准确性,提出了基于差分自回归滑动平均和长短期记忆神经网络的短期负荷联合模型预测方法,以避免单一预测模型可能难以满足预测准确需求的情况。首先,使用差分自回归滑动平均和长短期记忆神经网络单一模型对短期电力负荷开展预测;然后,使用改进的粒子群优化算法对联合模型权重进行寻优;最后,利用最优权重将单一模型预测结果进行合并得到最终的预测结果。验证结果表明,所建立的联合模型能够对短期电力负荷进行准确的预测,且联合模型的预测精度要优于差分自回归滑动平均、长短期记忆神经网络和BP神经网络等单一模型,具有一定的工程应用价值。     

广西新能源汽车发展SWOT分析

根据广西新能源汽车发展现状,综合分析了新能源汽车的产业优势、劣势、发展机遇和面临的挑战,提出了广西新能源汽车发展策略,建议科学制定广西新能源汽车发展规划、抓住国家新能源汽车战略性发展和"北部湾经济区"建设的机会、重点培育优势企业和产品以及优化区内新能源汽车产业结构等措施,以加快产业的发展。     

插电式混合动力汽车相关技术与前景展望

插电式混合动力汽车可以通过充电装置从电网获取电能,减少了对发动机的依赖.因其较多地使用网电,燃料消耗低,节能减排效果显著,被认为是一种当前最易接受的、市场前景乐观的混合动力电动汽车驱动模式.就插电式混合动力汽车相关技术进行阐述,旨在分析其产业化的技术瓶颈及其发展前景.     

Service‐based high‐speed railway base station arrangement

To provide stable and high data rate wireless access for passengers in the train, it is necessary to properly deploy base stations along the railway. We consider this issue from the perspective of service, which is defined as the integral of the time‐varying instantaneous channel capacity. With large‐scale fading assumption, it will be shown that the total service of each base station is inversely proportional to the velocity of the train. Besides, we find that if the ratio of the service provided by a base station in its service region to its total service is given, the base station interval (i.e., the distance between two adjacent base stations) is a constant regardless of the velocity of the train. On the other hand, if a certain amount of service is required, the interval will increase with the velocity of the train. The aforementioned results apply not only to simple curve rails, like line rail and arc rail, but also to any irregular curve rail, provided that the train is traveling at a constant velocity. Furthermore, the new developed results are applied to analyze the on–off transmission strategy of base stations. Copyright © 2013 John Wiley & Sons, Ltd.     

Non‐cooperative game‐based packet ferry forwarding for sparse mobile wireless networks

In sparse mobile wireless networks, normally, the mobile nodes are carried by people, and the moving activity of nodes always happens in a specific area, which corresponds to some specific community. Between the isolated communities, there is no stable communication link. Therefore, it is difficult to ensure the effective packet transmission among communities, which leads to the higher packet delivery delay and lower successful delivery ratio. Recently, an additional ferry node was introduced to forward packets between the isolated communities. However, most of the existing algorithms are working on how to control the trajectory of only one ferry work in the network. In this paper, we consider multiple ferries working in the network scenario and put our main focus on the optimal packet selection strategy, under the condition of mutual influence between the ferries and the buffer limitation. We introduce a non‐cooperative Bayesian game to achieve the optimal packet selection strategy. By maximizing the individual income of a ferry, we optimize the network performance on packet delivery delay and successful delivery ratio. Simulation results show that our proposed packet selection strategy improves the network performance on packet delivery delay and successful delivery ratio. Copyright © 2013 John Wiley & Sons, Ltd.     

Effect of AMC on fixed‐rate traffic with hard delay constraints in mobile broadband systems

The adaptive modulation and coding (AMC) technique, which has been adopted by advanced mobile telecommunication systems, supports a flexible response to the random radio behaviour. As a result, the attained transmission rate over a wireless link is time varying. Hence, resource demands are not deterministic but fluctuating even for calls with constant bit rate service requirements. Consequently, constant bit rate calls are susceptible to a forced call termination because of insufficient resources not only in a target cell during inter‐cell handoffs but also in a serving cell during radio link deterioration. Furthermore, call blocking and dropping probabilities depend on radio propagation conditions among other factors and therefore they are dissimilar throughout a service area. The latter leads to unfairness problems. We analytically measure the impact of AMC on fixed‐rate service with hard delay constraints such as voice for different signal, mobility and traffic conditions. We consider a reference case (call requests are admitted into the system provided there are enough free resources) and two classes of admission control approaches: traditional (only inter‐cell handoffs are prioritised) and modified (all ongoing calls are prioritised). The reported results reveal conditions for which AMC affects voice call performance and can serve as guidelines on admission control design. Copyright © 2013 John Wiley & Sons, Ltd.     

A classification control strategy for energy storage system in microgrid

Storage devices are indispensable elements in a microgrid to compensate for the power imbalance between loads and the distributed generator (DG) output. Different storage strategies give diverse performances in adjustment speed and capacity. Based on the performance of different storage devices and the features of power imbalance curve in different periods, a classification control strategy is proposed in this paper. First, storage devices are given priorities according to the adjusting speed, and the power imbalance curve is divided into two periods according to the changing speed. During an emergency, all the storages are employed to compensate the rapidly increasing power imbalance; during the steady period, storage device with higher priority is employed to track the instantaneous component of power imbalance, while storage device with lower priority is used to replace the kWh output of higher priority storage. The proposed strategy is tested in a microgrid within the subdistribution network of IEEE RBTS Bus6 system using Monte Carlo methods. Simulation results indicate that the classification control strategy could endow the system with fast adjusting ability through coordination between storages. Reliability indices of the testing system are utilized to demonstrate that the classification control strategy could improve the stability of the microgrid and reliability of the distribution network. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A new hybrid state estimation based on pseudo‐voltage measurements

This paper presents a new hybrid state estimation method based on the concept of pseudo‐voltage measurements for a power system containing both conventional and synchronizing phasor measurements. Actual measurement data is employed to calculate the magnitude and phase of the pseudo‐voltage. In the proposed formulation, the measurement matrix describing the relations between the measured data and the state variables contains only 0 or 1. Then the state estimation problem is formulated based on the weighted least‐squares criterion, and its solution can be obtained without using iterative procedures. Comparisons with previous hybrid state estimation methods have been performed on IEEE 14‐bus, 57‐bus, and 118‐bus systems. Numerical experimental results indicate that the proposed approach yields solutions of comparable accuracy with other methods but with shorter computation times. Moreover, the proposed method also provides superior results in the presence of bad data. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Dead‐time elimination SVPWM of six‐leg inverter

We present a six‐leg voltage source inverter (VSI) with a single DC link to feed a three‐phase inductive load. The space vector pulse width modulation (SVPWM) of the six‐leg inverter is studied in detail. The novel switching strategy in one sampling period for H bridge is proposed to avoid the 180° phase shift of the PWM signals for upper and lower side switches. Based on the novel switching strategy, a dead‐time elimination SVPWM is proposed, which can be easily implemented on a digital signal processor. Experimental results are presented to demonstrate the validity and features of the proposed novel SVPWM. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.