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The main goal of integrated energy service providers (IESP) in the future is to pursue profitability and reduce carbon emissions while ensuring sufficient energy supply. However, the multiple uncertainties associated with renewable energy resources and the multi‐energy consumers pose significant challenges in the optimal planning of the integrated energy system (IES) based on energy hubs (EH). This includes the global optimization of device types, EH capacity, and the optional interconnections between adjacent EHs. This study aims to develop a comprehensive mathematical model of EH that considers the temperature limitations on device operation. The thermal bus and associated devices are divided into high and low temperature parts, and a multi‐scenario stochastic programming model is proposed for IES planning. Scenarios are generated using non‐parametric kernel density estimation and the Copula function, a scenario reduction technique is implemented to alleviate computational burden. Additionally, case studies illustrate effectiveness of the proposed approach, the operation and forms of EHs, effect of the interconnections and the trade‐off between carbon emissions and economic costs are further studied by extensive simulations. This study can be a good guide for IESPs to invest in the construction of the EH‐based IES. [ABSTRACT FROM AUTHOR]

Energy routers based on the electronic power transformer are suitable for the AC–DC hybrid grid with multiple voltage levels, but their structures are complex. This paper proposes a novel energy router based on the multi‐winding line frequency transformer. By a combination of a multi‐winding line frequency transformer and power electronic devices, the proposed energy router can take advantage of the high reliability of the multi‐winding line frequency transformer and the high controllability of power electronic devices. The proposed energy router is suitable for the AC–DC hybrid grid with multiple voltage levels and has the characteristic of a simple structure. The simulations and experimental results demonstrate the effectiveness of the proposed energy router. [ABSTRACT FROM AUTHOR]

Recently, the grounding system of substation has been seriously invaded by earth current generated by flourishing urban rail transit network. The invasion leads to abnormal vibration of transformer and even some electrical safety problems. This article presents a dc and harmonic current suppression system (DHSS) applied to the neutral point of transformer. The design and development of the DHSS are described in detail. The power circuit is designed as a segmented structure with dc current blocking and harmonic current suppression. The high-speed bypass protection circuit is implemented to ensure the reliable grounding of neutral point in any case. The matching control and protection system is developed. The proposed controller for suppressing harmonic current is applicable for the neutral point and meets the requirements of relay protection. The design details and difficulties are discussed. The development, commissioning, and experiment are completed in the laboratory. The developed prototype has been subjected to high current impulse tests. The performance and reliability are verified by the presented results. This prototype is running on-site in a 220 kV substation. [ABSTRACT FROM AUTHOR]

A new optimal coordinated control strategy between an electronic power transformer (EPT) and generator excitation is proposed to improve power system dynamic performance and stability. The studied system is based on a single-machine multidouble-circuit transmission-lines (SMTL) system. In the SMTL system, the generator is connected to an infinite bus through a conventional power transformer with a double-circuit transmission fine, and to another infinite bus with an EPT with a double-circuit transmission line. The mathematical model of the SMTL system is established, and the proposed optimal coordinated control strategy is upon linear optimal control theory. Numerical simulations were carried out for the SMTL system, and the simulation results showed that the proposed control strategy has good dynamical performance for a variety of disturbances, and can improve the system damping and voltage performance effectively. Index Terms--Electronic power transformer (EPT), generator excitation, optimal control, power-electronic transformer (PET), transformer.