Wireless power transfer (WPT) technology enhances the portability, safety, and flexibility of electric vehicle charging. However, the leakage of electromagnetic fields (EMF) from the coupling coils, which are in an open environment, may pose health risks. In this paper, we first establish a mathematical model of the electromagnetic field for coupling coils in wireless charging applications for electric vehicles. Based on this model, the influence of excitation current and coil turns on leakage EMF is analyzed. Subsequently, we optimize the turns of the coupling coil through simulation to ensure that the leakage EMF meets relevant safety standards while maintaining the power level of the system, ensuring that the leakage EMF in the human-accessible area during full-power operation does not affect human health. Finally, we validate the electromagnetic safety of the system through simulation and experimentation. This paper provides guidance for the electromagnetic safety design and optimization of wireless charging systems applied to electric vehicles.

Abstract Power factor correction circuits are being used more extensively, and with that, the requirements and standards have become increasingly stringent. To improve the power factor of the circuit, thereby improving its operational efficiency and mitigating the load effects in boost power factor correction circuits, reducing Total Harmonics Distortion is crucial for improving the quality of the current. An improvement upon the conventional dual-loop PID control algorithm has been proposed. It involves integrating Model Predictive Control into the current loop design and incorporates a Luenberger observer. Model Predictive Control methods can be applied for the control of multivariable systems, especially in complex multivariable systems, as they exhibit strong robustness. Finally, by performing both simulation and experimental validations and analyzing the data results, it is shown that under full load conditions, the power factor λ is 0.968, the efficiency η is 91.11%, the voltage total harmonic distortion Uthd is 1.88%, and the current total harmonic distortion Ithd is 7.04%. These data results strongly confirm the performance of the control mechanism proposed in this paper.

Grid-connected photovoltaic (PV) systems are usually supposed to provide voltage support during grid faults to help the recovery of power system from voltage sags. This paper investigates the optimized distribution of active and reactive power of grid-connected PV system in case of balanced grid fault, with the purpose to provide maximum grid voltage support during fault conditions. Taking the grid impedance into consideration, the principles of voltage support during grid fault are analyzed in detail, which revealed that the maximum voltage support can be achieved by injecting active and reactive current proportional to the R/X ratio of the equivalent grid impedance. Meanwhile, it can be observed how the penetration level of PV systems exerts influences on the voltage support effect. Several scenarios of simulation are conducted to verify the theoretical analysis.

The virtual inertia technology of DGs (Distributed Generations) can provide inertia and damping support for the power system by imitating the traditional synchronous machine. However, the inherent delay problems around the communication and process links of the virtual inertia control will make an impact on the fast support effect. In this paper, the virtual inertia based hierarchical control scheme considering communication delay for distributed generations integration systems is proposed. The hierarchical control architecture including the PQ primary control and the virtual inertia based secondary control method which can realize the optimal power utilization and certain frequency support under the situation of communication signal delay at the same time. Firstly, the basic hierarchical control scheme for distributed generations and corresponding small signal modeling considering communication delay are presented. Then to enhance the inertia support ability of the distributed generation integration system, an improved hierarchical control strategy considering communication delay is designed based on the robust passivity method to compensate the equivalent delay disturbance. Finally, the effectiveness verification of the proposed control is carried out with the simulation cases in PSCAD platform.

The low-voltage distribution network is facing a situation of blowout, small capacity and decentralized distributed new energy access, with the emergence of large-scale power reverse transmission and frequent voltage fluctuations at station area level. However, power grid companies find it difficult to timely perceive real-time information of electricity generation and consumption within the station area, witch increasing the difficulty of operation control and management of the distribution network, and bringing adverse effects to safe, stable and economic power supply. Following the idea of edge computing, a real-time information acquisition and dispatching control method suitable for distribution station area with distributed new energy is proposed to realize the information interconnection and integration of local equipment at a lower cost, so that various adjustable resources can participate in the multi-level source network load interaction operation, and improve the comprehensive benefits of the distribution system in the station area.

我国分布式光伏呈现出"点多面广、局部高密度并网"的高速发展态势.随着分布式光伏渗透率的不断提升,分布式光伏出力对电网的影响日益增加.然而,分布式光伏数据采集条件不理想或通信测量设备异常状况较多,导致分布式光伏运行数据缺失或质量差,调度决策时无法准确掌握电网的实时运行状态,也无法事后准确分析还原故障状态,指导电网运行;另外,分布式光伏出力具有波动性和随机性,运行场景多样复杂,出力估计困难,增加了电网电力平衡压力以及运行风险.

In view of the risk that missing the goal of “carbon peaking and carbon neutrality” policy caused by the single emission reduction method of the consumer energy internet, this paper proposed an energy configuration method for the consumer energy internet based on carbon pinch analysis. Taking the optimal overall cost of the system as the goal, and fully considering the carbon emission constraints and the life cycle cost of distributed generations, the optimal energy consumption structure and distributed generation configuration scheme of the system were designed. This simulation results revealed that the method proposed in this paper provided technical support to realization of the “carbon neutrality” policy, by adjusting energy consumption structure, increasing clean energy installation, promoting electric power alternation, and reducing the system annual comprehensive cost.

This paper proposes an optimal planning Strategy to enhance the resilience of power distribution networks to protect against extreme events. Different resilience enhancement strategies, such as line hardening and energy storage configuration are considered for pre-disaster planning and disaster recovery. Firstly, a typical fault model for distribution lines in extreme scenarios is presented, and based on the spatiotemporal characteristics of extreme events, a fault uncertainty set for each stage of the line is established. Then, the faulty network is reconfigured to form the maximum supply path, fully utilizing available resources. Finally, the planning problem is formulated as a two-stage robust optimization model to minimize grid hardening investment and load shedding loss, and a solution algorithm is proposed to reduce the conservatism of the robust model. The proposed strategy was tested in a real power distribution system in Jiangsu Province, China. The result indicates that the coordinated method of transmission line hardening and energy storage configuration achieves comprehensive optimization of economy and resilience.

能源转型大环境下,综合能源系统得到了快速发展,多能流耦合的运行模式增加了运行的复杂性.当出现随机因素扰动时,综合能源系统的安全稳定运行会遇到威胁.针对这一问题,文中提出了综合考虑运行风险与韧性的综合能源系统薄弱环节辨识方法.首先,引入了基于半不变量法的电-热-气耦合综合能源系统概率多能流计算模型,基于概率多能流提出正常运行情况下的运行风险评估指标和评估方法.然后,针对极端灾害下的故障,从鲁棒性角度提出运行韧性评估指标.最后,综合考虑源荷随机变化和随机故障的不确定性扰动,提出风险-韧性双维度综合指标,判断综合能源系统的薄弱点.算例分析表明,所提计及风险和韧性的薄弱点辨别评估方法可以量化分析综合能源系统的薄弱环节,验证了所提方法的有效性.

考虑动力电池的损耗成本,提出一种电动公交车参与电动汽车与电网互动(V2G)的多时间尺度优化调度策略.首先,依据工程经济学原理建立动力电池的损耗模型.然后,在日前阶段的上层以公交公司的日运营成本最小为目标,采用迭代法对电池损耗成本和充电站的充放电计划进行联动优化;下层模型在上层优化结果的基础上,以配电网负荷峰谷差最小为目标,进一步优化充电站的充放电计划.日内阶段对光伏出力和配电网基础负荷功率进行滚动更新,以公交公司日运营成本最小和日前、日内计划偏差最小为目标对日前计划进行修正.最后,从公交公司和电网2个角度对无序充电、有序充电、参与V2G的3种方案进行对比分析,验证了电动公交车参与V2G时的优越性,并通过灵敏度分析表明不同V2G补偿系数下公交公司运营成本的变化趋势.

As an important part of energy internet and the main supporting form of social energy, the integrated energy system (IES) is the important development direction for the new round of energy transformation. As the extension and expansion of power grid dispatching system, the coordinated control system of regional IES performs the lean and ubiquitous dispatching control of multi-energy flow for related energy equipment in the region. Based on the three-layer architecture of the IES, the important role of the regional IES is analyzed. The topological relationship, and the hardware and software structure of regional integrated energy coordinated control system are proposed. The system platform services, basic applications, and advanced application functions are studied. A software for the regional integrated energy coordinated control system is developed, and has been applied and verified in Tongli new energy town integrated energy demonstration area. It will be further promoted and applied in the future.

In this paper, a production simulation method of regional integrated energy system considering the randomness of the scene is proposed to solve the production decision problem of integrated energy system including wind power, photovoltaic and other intermittent renewable energy sources. This method firstly establishes the typical scenario set of the integrated energy system operation with the corresponding random probability through cluster analysis. Secondly, taking the regional integrated energy system as the object, a production decision model and algorithm with the goal of minimizing the expected energy consumption cost are proposed. Finally, the effectiveness of the model algorithm is verified by a case study.

With the development of second-use technology, it is possible to reorganize the retired electric bus batteries (EBBs) into the echelon battery system (EBS). To quantify the value of coordinated operation of EBS-EBBs for an electric bus charging station (EBCS), a configuration-control integrated strategy is proposed. In the configuration stage, the number of second-used electric bus batteries (SUEBBs) is optimized to minimize the overall equivalent annual cost (EAC) of EBCS, based on the evaluation model of SUEBBs' replacement. In the control stage, the coordinated charging-discharging power of EBS and EBBs is optimized in order to minimize the daily electricity cost of EBCS. Finally, six scenarios are compared and analyzed to verify the economy of equipping EBS in the EBCS. Meanwhile, the impact of the lifespan and price of SUEBBs is analyzed by sensitivity analysis.

This work proposes a distributed optimization strategy for integrated energy system (IES) based on alternating direction method of multipliers (ADMM). Firstly, uncertain factors from source and load sides are analyzed, and scenario method is utilized to describe their stochastic characteristics. Then, IES optimal scheduling model is established. Next, the principle of ADMM is clarified and aforementioned model is thus reformulated via ADMM to realize the distributed solution for multi-energy complementation. Finally, the effectiveness and feasibility of proposed strategy are verified by the results of case study.

Under the impact of various uncertainties, the potential operation risk of the distribution network is gradually gaining more and more attention in both security and economy. To comprehensively determine the risk level, an operational risk assessment method considering multiple risk factors is proposed. Firstly, probabilistic models are established including temporal distributions of electric vehicles and uncertainties of renewable energy. Secondly, a time-sequential security risk assessment method with several security indicators including overvoltage risk, undervoltage risk, line-overload risk and load-loss risk is established using probabilistic load flow and dynamical sensitivity weight analysis method. Thirdly, conditional value at risk model is presented for time-varying economic risk considering line-loss risk and operational profit or loss risk of distributed generations. Finally, a risk early warning standard is proposed to realise the visualisation of risk warning by defining the risk level and risk area. Simulations of different scenarios are conducted on the modified IEEE 34-bus radial test system and the results reveal that the proposed strategy is effective and practical.

Nowadays, the active distribution network (ADN) is facing great challenges on safe operation and coordinated scheduling. To resolve these issues, a novel multi-period active-reactive coordination scheduling strategy efficient solution method is proposed in this paper after addressing the uncertainty of DG and load by probabilistic scenario method. Firstly, based on the second-order cone relaxation (SOCR), the power flow equations are convexized and relaxed to transform the original model into mixed integer second-order cone programming (MISOCP). Then, the controllable resources such as on-load tap changer (OLTC), capacitor banks (CB) and ESS are accurately linearized, so the model is converted to 0–1 MISOCP problem. Finally, compared with the existing strategies, numerical tests on the modified IEEE 33-bus test system demonstrate that on the premise of realizing the maximum utilization of DG, the proposed strategy can also achieve the purposes of energy-saving, loss reduction and improvement in voltage level and the utilization of ESS. Meanwhile, the accuracy and efficiency of the 0–1 MISOCP model are verified through four operating schemes. In addition, the sensitivity analysis of adjustment step and action time of the discrete adjustment devices on optimization results is carried out in detail.

At present, more and more integrated energy projects are built by power grid companies all over the country. These projects all contain source, network, load and storage. But there is no uniform evaluation standard. In order to guide the planning of such projects and check the implementation effect of the planning in time, this paper establishes a set of evaluation index system for the coordination of source-network-load-storage. Four typical cases were scored with the index system. The industry's most praised integrated energy system got the highest score. This also proves the validity and rationality of the method.

Aiming at the ever-increasing trend of distributed energy resources (DER), this paper proposes a home/community integrated energy management model based on electric energy routers (EER). Firstly, based on the modeling of energy storage and controllable load in home energy Local Area Network (LAN), a home-level collaborative scheduling model is proposed. Then, considering the power interaction between homes, a community dispatching model is established to minimize the electricity charge and improve the utilization ratio of renewable energy. Cplex18.0 is used to solve the daily optimal electricity plan. Finally, the results of the case study verify the effectiveness and economy of the proposed model by comparing community's cost under different modes.

针对现有配电自动化系统中利用馈线终端设备和故障指示器等配电终端实现线路运行工况远程监测和故障定位所表现出的不足,提出了一套新型配电线路监测方法,并基于云计算技术开发了配电线路小电流接地故障监测系统.该监测系统集智能电网传感器、无线通信和云计算技术应用平台于一体,使得配供电系统透明可见,可提高配电网运行的经济性和可靠性.