A Wasserstein distributionally robust planning model for renewable sources and energy storage systems under multiple uncertainties

Nowadays, electricity markets and carbon trading mechanisms can promote investment in renewable sources but also generate new uncertainties in decision-making. In this paper, a two-stage Wasserstein distributionally robust optimization (WDRO) model is presented to determine the optimal planning strategy for renewable energy generators (REGs) and energy storage systems (ESSs) in the distribution network. This model considers supply-side and demand-side uncertainties in the distribution network and the interaction uncertainty from the main grid which are depicted by the ambiguity sets based on the Wasserstein metric and historical data. Meanwhile, both 1-norm and -norm Wasserstein metric constraints are considered to satisfy the decision-makers different preference. Furthermore, to solve this WDRO model, a systematic solution method with a three-step process is developed. Numerical results from a modified IEEE 33-node system and a 130-node system in the real world demonstrate the advantages of the two-stage WDRO model and the effectiveness of the solution method.</p

Topological properties of medium voltage electricity distribution networks

With a large penetration of low carbon technologies (LCTs) at medium voltage and low voltage levels, electricity distribution networks are undergoing rapid changes. Much research has been carried out to analyse the impact of employing LCTs in distribution networks based on either real or synthetic network samples. Results of such studies are usually case specific and of limited applicability to other networks. Topological properties of a distribution networks describe how different network components are located and connected, which are critical for the investigation of network performance. However, the number of network modelling and simulation platforms are limited in the open literature which can provide random realistic representations of electricity distribution networks. Thus, it is difficult to arrive to generalized and robust conclusions on impact studies of LCTs. As the initial step to bridge this gap, this paper studies the topological properties of real-world electricity distribution networks at the medium voltage level by employing the techniques from complex networks analysis and graph theory. The networks have been modelled as graphs with nodes representing electrical components of the network and links standing for the connections between the nodes through distribution lines. The key topological properties that characterize different types (urban and sub-urban) of distribution networks have been identified and quantified. A novel approach to obtain depth-dependent topological properties has also been developed. Results show that the node degree and edge length related graph properties are a key to characterize different types of electricity distribution networks and depth dependent network properties are able to better characterize the topological properties of urban and sub-urban networks

Multi-stage expansion planning of energy storage integrated soft open points considering tie-line reconstruction

With the rapid development of flexible interconnection technology in active distribution networks (ADNs), many power electronic devices have been employed to improve system operational performance. As a novel fully-controlled power electronic device, energy storage integrated soft open point (ESOP) is gradually replacing traditional switches. This can significantly enhance the controllability of ADNs. To facilitate the utilization of ESOP, device locations and capacities should be configured optimally. Thus, this paper proposes a multi-stage expansion planning method of ESOP with the consideration of tie-line reconstruction. First, based on multi-terminal modular design characteristics, the ESOP planning model is established. A multi-stage planning framework of ESOP is then presented, in which the evolutionary relationship among different planning schemes is analyzed. Based on this framework, a multi-stage planning method of ESOP with consideration of tie-line reconstruction is subsequently proposed. Finally, case studies are conducted on a modified practical distribution network, and the cost–benefit analysis of device and multiple impact factors are given to prove the effectiveness of the proposed method

Optimization Design of Core Ultra-Stable Structure for Space Gravitational Wave Detection Satellite Based on Response Surface Methodology

In order to meet the urgent demand for novel zero-expansion materials and ultra-stable structures in space gravitational wave detection, it is necessary to develop an ultra-stable structural spacecraft system. This paper focuses on the research of the optimization of the core ultra-stable structure design of spacecraft, proposing a cross-scale parameterized model of structural deformation response and a multi-objective optimization method. By satisfying the prerequisites of mass and fundamental frequency, this paper breaks through the limitations of current linear analysis methods, and the overall thermal deformation of nonlinear material composite structures is optimized by modifying structural parameters

Experimental Investigation of Thermal Runaway Characteristics of Large-Format Li(Ni_0.8Co_0.1Mn_0.1)O₂ Battery under Different Heating Powers and Areas

This study experimentally investigates the effects of different heating powers and areas on the jet behavior and thermal runaway (TR) of 75 Ah LiNi0.8Co0.1Mn0.1O2 pouch lithium-ion batteries (LIBs) in an open environment. TR, a critical safety concern for LIBs, can occur under overheating conditions. The TR behavior of LIBs was characterized by flame behavior, temperature characteristics, mass variation, jet dynamics, and residue formations. The results reveal that the heating power density primarily influences the time to initiate TR. Lower power densities extend the heating time and require higher energy to induce TR, thereby exerting a more considerable impact on the battery. The heating area predominantly affects the input energy and the extent of damage. Larger areas lead to more stable jet flames, consistent peak temperatures ranging between 1000 °C and 1300 °C, and mass loss ratios ranging from 44% to 53% compared to 43% to 47% for small-area heaters. These findings provide references for the safety design of battery assemblies and the prevention of TR propagation, contributing to the safer monitoring of LIBs

Balanced cross-section and crustal shortening analysis in the Tanggula-Tuotuohe Area, Northern Tibet

The Tanggula (唐古拉) thrust system and the Tuotuohe (沱沱河) foreland basin, which represent major Cenozoic tectonic units of the central Tibetan plateau, have been recently studied. Field investigation, analyses of deformation and construction of two restored balanced structural sections suggest 75–100 km (51%–64%) of N-S shortening in the Tanggula thrust system and 55–114 km (42%–47%) of N-S shortening in the Tuotuohe basin. The shortening ratios indicate that the Tanggula-Tuotuohe area has undergone intensive deformation and crustal shortening during the Early Tertiary, resulting not only in crustal thickening, but also in large scale volcanism and in rapid uplift of the Tanggula Mountains

Smooth Surface Roughness Of Silanized Cdse(Zns) Quantum Dots

The interparticle distance of CdSe(ZnS) quantum dots was accurately controlled by polymerization at the air-water interface which provided an increased homogeneity of the Langmuir-Blodgett film leading to a surface smoothness comparable to mica. The choice of a silane derivative is based on the fact that silicon is semiconductor, and the compound CdSe being the core of the quantum dot is also semiconductor. The combination of the two semiconductors could bring some unusual conduction properties as a polymeric silanized network. But first, it is most important to characterize the smoothness of the surface, which might be correlated to the formation of trap states, i.e. the photo-excited electron can fall, or the photo-excited hole can float One will focus our research strategy, as a pilot study, to characterize the surface of the new polymeric material. © 2012 Elsevier Inc