This work presents a new coordinated operation (CO) framework for electricity and natural gas networks, considering network congestions and demand response. Credit rank (CR) indicator of coupling units is introduced, and gas consumption constraints information of natural gas fired units (NGFUs) is given. Natural gas network operator (GNO) will deliver this information to an electricity network operator (ENO). A major advantage of this operation framework is that no frequent information interaction between GNO and ENO is needed. The entire framework contains two participants and three optimization problems, namely, GNO optimization sub-problem-A, GNO optimization sub-problem-B, and ENO optimization sub-problem. Decision sequence changed from traditional ENO-GNO-ENO to GNO-ENO-GNO in this novel framework. Second-order cone (SOC) relaxation is applied to ENO optimization sub-problem. The original problem is reformulated as a mixed-integer second-order cone programming (MISOCP) problem. For GNO optimization sub-problem, an improved sequential cone programming (SCP) method is applied based on SOC relaxation and the original sub-problem is converted to MISOCP problem. A benchmark 6-node natural gas system and 6-bus electricity system is used to illustrate the effectiveness of the proposed framework. Considering pipeline congestion, CO, with demand response, can reduce the total cost of an electricity network by 1.19%, as compared to −0.48% using traditional decentralized operation with demand response.
Tree pruning is a very important work in forestry production, which plays an important role in the growth and lumber of trees. In the general environment of automatic production of machinery, the market urgently needs a robot that can realize pruning work to replace a large amount of manual labor and increase the economic benefits of forests. In this paper, a tree-climbing and pruning robot with simple operation and automatic climbing function suitable for trimming a variety of trees is designed. The climbing mechanism of the robot adopts an enveloping wheel climbing structure, and the wheels are installed obliquely to achieve spiral ascent. The pruning mechanism adopts a combination of a mechanical arm and a saw blade, which can change the pruning method according to actual work requirements.
This paper presents an energy arbitrage strategy of a lithium-ion Battery Storage System (BSS) in sequential Day-ahead and Intraday (DA+INT) markets, considering its Cycle Aging Cost (CAC). One of the critical queries of the BSS in such problems is how to tackle the risk of uncertain prices in both market floors. Towards this end, a financial risk management method, i.e., Second-Order Stochastic Dominance Constraints (SOSDCs), is used to control the risk of uncertain market prices. Despite the promising performance of the SOSDCs over a broad range of decision-making problems, the primary challenge for decision-makers taking advantage of this approach is the selection of the minimum profit threshold. To effectively overcome this obstacle, this paper proposes a new benchmark selection approach based on a fuzzy decisionmaking manner over in-sample and out-of-sample analyses. The idea behind considering both in-sample and out-of-sample studies lies in an unforeseen change of the results by setting various benchmarks in SOSDCs. In this regard, to precisely formulate this problem, with an eye on the battery CAC, a linear two-stage stochastic framework is suggested. The numerical results show the applicability of the developed approach in benchmark selection for the SOSDCs.
In the tree-climbing robot, the sawing module is lifted and lowered by the planetary roller lead screw, so the dynamic analysis of the planetary roller lead screw is very important. In this paper, the stiffness of the mechanical joint of planetary roller lead screw is calculated according to the fractal theory, and the stiffness calculation formulas between roller and ring gear, roller and lead screw are obtained. In the dynamic simulation, the stiffness of each contact pair is set according to the formula, and two groups of models with consistent and inconsistent roller contact stiffness are established. The first six order modal analysis results of the two groups of models are compared, and the influence of uneven roller contact stiffness distribution on the whole planetary roller lead screw is obtained.
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