Conventional fundamental frequency zero-sequence voltage (FFZSV) injection-based fault-tolerant operation methods cause power reversion under submodule (SM) failure conditions with low-power factor, which leads to overcharge risk in the cascaded H-bridge converter-based battery energy storage system (CHB-BESS). To solve this issue, a novel fault-tolerant operation approach has been proposed for the CHB-BESS. First, the power reversion mechanism and overcharge risk are analyzed with the conventional FFZSV injection-based methods. On this basis, the operation conditions of the CHB-BESS are divided into three stages according to the safe FFZSV injection region, the FFZSV is modified, and the negative sequence current is injected when necessary. As a result, the power flow of battery packs among the three phases can maintain the same direction, and the power reversion and overcharge risk can be avoided. Experimental results under various conditions verify that the proposed fault-tolerant operation approach of the CHB-BESS can achieve uninterrupted operation and avoid overcharge risk.

The scale of electric vehicles (EVs) in microgrids is growing prominently. However, the stochasticity of EV charging behavior poses formidable obstacles to exploring their dispatch potential. To solve this issue, an optimization strategy for EV-integrated microgrids considering peer-to-peer (P2P) transactions has been proposed in this paper. This research strategy contributes to the sustainable development of microgrids under large-scale EV integration. Firstly, a novel cooperative operation framework considering P2P transactions is established, in which the impact factors of EV charging are regarded to simulate its stochasticity and the energy trading process of the EV-integrated microgrid participating in P2P transactions is defined. Secondly, cost models for the EV-integrated microgrid are established. Thirdly, a three-stage optimization strategy is proposed to simplify the solving process. It transforms the scheduling problem into three solvable subproblems and restructures them with Lagrangian relaxation. Finally, case studies demonstrate that the proposed strategy optimizes EV load distribution, reduces the overall operational cost of the EV-integrated microgrid, and enhances the economic efficiency of each microgrid participating in P2P transactions.

In order to study the degradation mechanism of lithium-ion batteries subjected to vibration aging in actual use and also to achieve capacity estimation and prediction, the following work has been done: First, the road spectra of two commonly seen domestic roads in China are collected in the field and modeled on a six degrees-of-freedom motion platform as the vibration working conditions of the batteries. Second, aging cycle experiments were conducted on batteries with different placement directions (X-axis direction, Y-axis direction, and Z-axis direction) under two vibration conditions, and the effects of experimental conditions on the decline results were analyzed; third, quantification of battery decline patterns to analyze the main causes of battery capacity decline; and then, through further analysis of the two vibration conditions on the lithium battery by in-situ and ex-situ methods as its internal mechanisms. Finally, the quantified results were input into the generative adversarial networks and long-term and short-term memory network prediction model to predict the capacity, and the errors of 20 predictions are as follows: the average values are 2.8561% for Group X, 2.7997% for Group Y, 3.0182% for Group Z, and 2.9478% for Group N, which meet the requirements of battery management system estimation. This paper provides a basis for the study of aging mechanism and capacity estimation of lithium-ion batteries under vibration aging conditions, which helps manufacturers to package batteries more rationally to extend battery life and develop battery management system (BMS)-related strategies.

Since traditional simulations do not reflect true morphological changes of the contact surface in relay contacts, the concept of difference-plane is proposed in this paper to establish the contact resistance model according to the actual shapes of the disassembled contacts, considering the hypothetical contact state of static and dynamic contacts. The difference-plane is restituted from the mechanical and electrical properties by analyzing the elements types and distributions, ignoring the influence of thermodynamics and membrane resistance. The contact resistance sliding coefficient is defined from the movement process of the sealed relay. The contact resistance model of the sealed relay is established by using the dimensionless parameter as the mediator, which provides a new idea for contact resistance modeling from the actual contact morphology point.