Distributed photovoltaic (PV) in the distribution network accounted for an increasing proportion of the distribution network, and the power quality of the distribution network of the power quality problem is more and more significant. In this paper, the voltage regulation methods for low-voltage distribution networks containing high-penetration PV are investigated. First, the working principles of the four voltage control methods are introduced: energy storage system configuration, regulating the reactive power output of PV inverters, restricting the active power output of PV, adjusting the switching positions of on-load regulator trap changer and distribution network reconfiguration, and then, in combination with the recent related research, the optimization of each method is compared horizontally with its respective concerns and characteristics. The optimization of each method is compared horizontally with the recent studies to find out the focus and characteristics of each method, and the shortcomings of each method are explored. Coordinated voltage control through multiple flexibility resources has become the mainstream voltage regulation scheme, and distribution network voltage regulation is considered from the perspective of flexibility resources. The three types of flexibility resources, namely, source, network, and storage, have been widely used in distribution network voltage regulation. Although load-side resources have become one of the main regulation resources of the new type of power system, the current study introduces less about the participation of load-side flexibility resources in voltage regulation of LV distribution networks and advancing the application of load-side resources in voltage regulation of LV distribution networks is the focus of future research. Then, the important role of load-side flexibility resources in voltage regulation is described in three parts, namely, the important role of load-side resources, the development trend, and the suggestions for promoting the coordination of source-network-load-storage flexibility resources, aiming to promote the application of load-side resources in voltage regulation in LV distribution networks, and the suggestions and programs are proposed for the technological challenges faced by voltage regulation. In the context of today’s new power system emphasizing the interaction of source, network, load, and storage, new technologies and methods for solving voltage problems in LV distribution networks are prospected, with a view to providing certain reference value for the actual operation and optimization of distribution network systems.

In this paper, the method of stator current and noise combination is introduced for inter-turn short-circuit fault recognition in permanent magnet synchronouse motor. The detection and diagnosis system consists of sensors, USB5935 data acquisiton card USB5935 and a computer with LabVIEW installed. The frequency pattern of stator current is extracted from the monitored stator current and the amplitude of increase is obtained. The frequency pattern of noise is extracted from the monitored noise and the main fault frequency is found. The frequency pattern of stator current and the amplitude of increase are introduced as a main criterion to diagnose the inter-turn short-circuit fault. The frequency pattern of noise is introduced as a secondary criterion. The experiment shows that the combination of the stator current and noise is helpful to diagnose the small inter-turn short-circuit fault of permanent magnet synchronouse motor.

This paper presents a heat transfer matrix and superposed thermal field-based method that can rapidly calculate steady state temperature rises in three-core cable groups laid in ducts. The temperature rise of any cable is a combination of self-reaction and interaction from other cables. A heat transfer matrix is formed by self-reaction coefficient and interaction transfer coefficient representing the thermal characteristics of the cable groups in ducts. The heat transfer matrix can be obtained by enough samples including temperature rise and cable losses based on numerical analysis, trial or commercial software. Rapid calculations can then be performed by simplify iteration of temperature-loss. Extraction of the transfer matrix using CYMCAP ampacity and temperature calculation software and application of the fast calculation method are illustrated and compared, confirming the feasibility and relative simplicity and accuracy of the fast calculation method.

In this article, by the fixed point theorem in a cone and the nonlocal fourth-order BVP's Green function, the existence of at least one positive solution for the nonlocal fourth-order boundary value problem with all order derivatives u ( 4 ) ( t ) + A u ″ ( t ) = λ f ( t , u ( t ) , u ′ ( t ) , u ″ ( t ) , u ‴ ( t ) ) , 0 < t < 1 , u ( 0 ) = u ( 1 ) = ∫ 0 1 p ( s ) u ( s ) d s , u ″ ( 0 ) = u ″ ( 1 ) = ∫ 0 1 q ( s ) u ″ ( s ) d s is considered, where f is a nonnegative continuous function, λ > 0, 0 < A < π 2, p, q ∈ L[0, 1], p(s) ≥ 0, q(s) ≥ 0. The emphasis here is that f depends on all order derivatives.

A three-port DC-DC converter (TPC) for photo-voltaic (PV) electric vehicle (EV) was presented in this paper. A PV module and a battery consist of the power supply for electric vehicle. A boost converter helps the PV module to output maximum power. A sepic-zeta converter helps the battery to be charged by PV power or output power for EV. A cuk converter was used to keep the stability of output voltage for load. There are five modalities for the TPC model and three applications were simulated to verify the performance of different modality switching. The simulation results show that the given TPC model have some advantages, such as small steady errors, short transient times and small fluctuation of voltage and power. This TPC can be used in EV to provide a steady voltage for motor and extend the driving distance.