The Local Ordered Charging Strategy of Electric Vehicles Based on Energy Routers under Three-Phase Balance of Residential Fields

With the popularization of electric private cars and the increase of charging facilities in residential areas, disorderly charging will affect the power supply efficiency of their distribution transformers and the quality of electricity used by users in residential areas. In severe cases, it may even cause vibration of the power grid, causing serious three-phase imbalance problems such as single-phase burnout of transformers or insulation breakdown of household appliances. This paper analyzes the influencing factors of the unbalanced operation of each phase of the distribution transformer and the electrical load characteristics of typical residential areas. Based on the photovoltaic output of the station area, the charging and discharging capacity of the energy storage system, and the orderly charging plan of residential electric vehicles, a local orderly charging strategy for electric vehicles based on energy routers under the three-phase balance of the residential area is proposed. This strategy can realize the three-phase balance control of the distribution transformer. The effectiveness of the method is verified by a typical scenario example. The control method is changed to minimize the three-phase imbalance in residential areas and improve the low utilization rate of the distribution network and the comprehensive utilization efficiency of adjustable resources in residential areas.

Forecasting Hydrocarbon Production at Gas Condensate Fields Considering Phase Transformations of Reservoir Systems

Based on the results of PVT studies, a methodology for estimating hydrocarbon recovery at various stages of a gas condensate field development, depending on the current weighted average reservoir pressure in the gas drive, is considered. In this case, the physical processes related to the phase transformations of the reservoir gas condensate mixture with a decrease in reservoir pressure in the deposit are assumed identical in the PVT bomb. That is, the effect of the porous medium is neglected. This allows describing the processes of phase transformations with the same equation of material balance, based on which it is possible to forecast hydrocarbon recovery at gas condensate fields, and provide a control over the results of phase transformation modelling of the reservoir gas condensate mixture in phase balance bomb (PVT bomb).

Operation of Distributed Battery Considering Demand Response Using Deep Reinforcement Learning in Grid Edge Control

Battery energy storage systems (BESSs) are able to facilitate economical operation of the grid through demand response (DR), and are regarded as the most significant DR resource. Among them, distributed BESS integrating home photovoltaics (PV) have developed rapidly, and account for nearly 40% of newly installed capacity. However, the use scenarios and use efficiency of distributed BESS are far from sufficient to be able to utilize the potential loads and overcome uncertainties caused by disorderly operation. In this paper, the low-voltage transformer-powered area (LVTPA) is firstly defined, and then a DR grid edge controller was implemented based on deep reinforcement learning to maximize the total DR benefits and promote three-phase balance in the LVTPA. The proposed DR problem is formulated as a Markov decision process (MDP). In addition, the deep deterministic policy gradient (DDPG) algorithm is applied to train the controller in order to learn the optimal DR strategy. Additionally, a life cycle cost model of the BESS is established and implemented in the DR scheme to measure the income. The numerical results, compared to deep Q learning and model-based methods, demonstrate the effectiveness and validity of the proposed method.

A Review of Passive and Active Ultra-Wideband Baluns for Use in Ground Penetrating Radar

Microwave ultra-wideband technology has been widely adopted in instrumentation and measurement systems, including ground-penetrating radar (GPR) sensors. Baluns are essential components in these systems to feed balanced antennas from unbalanced feed cables. Baluns are typically introduced to avoid issues with return signals, asymmetrical radiation patterns and radiation from cables. In GPR systems, these issues can cause poor sensitivity due to a reduction in radiated power, blind spots due to changes in the radiation pattern and additional clutter from common mode radiation. The different balun technologies currently available exhibit a wide variation in performance characteristics such as insertion loss, reflection coefficient and phase balance, as well as physical properties such as size and manufacturability. In this study, the performance of two magnetic transformer baluns, two tapered microstrip baluns and an active balun based on high-speed amplifiers were investigated, all up to frequencies of 6 GHz. A radio frequency current probe was used to measure the common mode currents on the feed cables that occur with poor performing baluns. It was found that commercially available magnetic transformer baluns have the best phase linearity, while also having the highest insertion losses. The active balun design has the best reflection coefficient at low frequencies, while, at high frequencies, its performance is similar to the other baluns tested. It was found that the active balun had the lowest common mode current on the feed cables.

Synthesis of Functional Surface Layers on Stainless Steels by Laser Alloying

Laser alloying is an effective method to form functional surface layers (coatings) on metallic materials, particularly on stainless steels. Unique phase balance, dislocation substructure, and a possibility to obtain gradient microstructures after laser alloying slow down the surface degradation and increase the wear resistance. In this work, the optimal parameters of laser alloying and their effects on microstructure and properties were investigated for two stainless steels: ferritic AISI 420 and austenitic AISI 304. Three types of alloying plasters were used: 85Nb + 15 graphite, 85Nb + 15 liquid glass, and 15Fe + 30Ni + 20B + 10Si + 25 liquid glass (wt.%). The laser power density of 0.3 × 105 W/cm2 and beam scanning speed of 1990 mm/min were found to generate 220–320 μm thick coatings with complex microstructures. Phase balance in the coatings was studied with X-ray diffraction and magnetometric phase analyses. High microhardness (up to 16 GPa) and wear resistance were associated with the formation of martensite with some retained austenite and Nb-, Cr-, Si-, and B-rich particles in the surface layer of AISI 420 steel, and high dislocation density austenite strengthened with Ti-, Nb-, Cr-, and Si-rich particles in AISI 304 steel.

Research on the control strategy of phase balance in H-bridge cascade SVG

Based on the H-bridge cascaded SVG as one of the best solutions to effectively compensate reactive currents, this article focuses on the cascaded high-voltage H-bridge SVG phase balance problem. While analyzing the influence factors of the SVG DC side voltage, it summarizes and introduces 5 SVG phase balance control strategy ， Analyzed its real-time performance, stability, applicable occasions, algorithm and hardware circuit complexity, etc.Some control strategies have been simulated and verified, and the simulation results have reached the expected value, which provides a reference for the selection of balance control strategies for high-voltage SVG equipment.