The Ubiquitous Power Internet of Things (UPIoT) is a concrete manifestation of the Internet of things (IoT) in the power industry, which is a deep integration of the interconnected power network and communication network, realizing full perception of the system status and full business penetration in all links of power production, transmission, and consumption. The introduction of edge computing in UPIoT fully meets the requirements of rapid response, real-time perception, and to some extent, privacy protection. However, there is currently no comprehensive investigation on the application of edge computing technology in UPIoT. First, this paper introduces the development background and construction of UPIoT and its technical architecture. Then the challenges faced by UPIoT in the process of construction are analyzed. Furthermore, the paper elaborates on the functions and features of edge computing, proposes that the support of edge computing technology can solve the challenges of efficient, fast, and secure processing of massive edge data faced by the traditional cloud-based centralized big data processing technology of UPIoT, and analyzes the architecture of the edge computing-assisted UPIoT. For the three typical scenarios of UPIoT, namely power monitoring system, smart energy system and power metering system, the edge computing architecture of the three scenarios are analyzed, and the specific application methods and roles played by edge computing in the three scenarios are also elaborated. Finally, we discuss the challenges of edge computing in UPIoT, in terms of policy challenges, market challenges, and technical challenges, as well as outline the outlooks of the technical challenges.

No abstract

No abstract

In this paper, the stability of direct current (DC) microgrids with a constant power load (CPL) and a non-ideal source is investigated. The CPL’s negative impedance will destabilize the system, and disturbances in the non-ideal source will degrade the load voltage quality. In this study, we aim to: (1) overcome the instability of the CPL; (2) mitigate disturbances from the non-ideal source; (3) prevent the discontinuous harmonic current of high-frequency switching regulator from interfering with the source. Then, a stabilization method based on active damping which can achieve the above three objectives simultaneously is proposed. To obtain the stability conditions, the small-signal model of the system near the high-voltage equilibrium is established. Then, stability conditions are derived by eigenvalue analysis, and the domain of attraction near equilibrium is also obtained using the quadratic Lyapunov function. For the second objective, the key is to choose the optimal parameters to achieve disturbance attenuation. For the third objective, the active damper can separate the source from the switching regulator, which can prevent the discontinuous harmonic current. Moreover, the proposed method can be extended to multiple cases, and simulation results verify the effectiveness of the proposed method.

No abstract

No abstract

With the rapid development of e-commerce in China, the scale of express delivery industry is also expanding rapidly, while the quality of express delivery service has not been effectively improved, with a high value of number lying in the complaint rate of express delivery industry, which leads to low customer satisfaction. Based on the service quality evaluation model, this paper designs the questionnaire with the help of the Richter scale, also constructs the evaluation index of express service quality based on customer satisfaction, with the analysis of the factors through the use of SPSS 23, this essay finds out the main factors that affect the customer’s satisfaction with express service quality,and put forwards corresponding suggestion for improvement.

No abstract