scholarly journals On Global, Closed-Form Solutions to Parametric Optimization Problems for Robots With Energy Regeneration

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Poya Khalaf ◽  
Hanz Richter
Keyword(s):  
Energy Storage ◽  
Closed Form ◽  
Parametric Optimization ◽  
Optimization Problems ◽  
Electric Energy ◽  
Energy Utilization ◽  
Closed Form Solutions ◽  
Motion Trajectories ◽  
Asymptotic Tracking ◽  
Regenerative Energy

Parametric optimization problems are considered for serial robots with regenerative drive mechanisms. A subset of the robot joints are conventional, in the sense that external power is used for actuation. Other joints are energetically self-contained passive systems that use (ultra)capacitors for energy storage. Two different electrical interconnections are considered for the regenerative drives, a distributed and a star configuration. The latter allows for direct electric energy redistribution among joints, a novel idea shown in this paper to enable higher energy utilization efficiencies. Closed-form expressions are found for the optimal manipulator parameters (link masses, link lengths, etc.) and drive mechanism parameters (gear ratios, etc.) that maximize regenerative energy storage between any two times, given motion trajectories. A semi-active virtual control strategy previously proposed is used to achieve asymptotic tracking of trajectories. Optimal solutions are shown to be global and unique. In addition, closed-form expressions are provided for the maximum attainable energy. This theoretical maximum places limits on the amount of energy that can be recovered. The results also shed light on the comparative advantages of the star and distributed configurations. A numerical example with a double inverted pendulum and cart system is provided to demonstrate the results.

scholarly journals A Dual-Objective Substation Energy Consumption Optimization Problem in Subway Systems

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1876 ◽  
Author(s):  
Hongjie Liu ◽  
Tao Tang ◽  
Jidong Lv ◽  
Ming Chai
Keyword(s):  
Energy Consumption ◽  
Energy Storage ◽  
Energy Conservation ◽  
Optimization Problem ◽  
Optimization Problems ◽  
Energy Utilization ◽  
Total Size ◽  
Energy Consumption Optimization ◽  
Regenerative Energy ◽  
Timetable Optimization

Maximizing regenerative energy utilization is an important way to reduce substation energy consumption in subway systems. Timetable optimization and energy storage systems are two main ways to improve improve regenerative energy utilization, but they were studied separately in the past. To further improve energy conservation while maintaining a low cost, this paper presents a strategy to improve regenerative energy utilization by an integration of them, which determines the capacity of each Wayside Energy Storage System (WESS) and correspondingly optimizes the timetable at the same time. We first propose a dual-objective optimization problem to simultaneously minimize substation energy consumption and the total cost of WESS. Then, a mathematical model is formulated with the decision variables as the configuration of WESS and timetable. Afterwards, we design an ϵ -constraint method to transform the dual-objective optimization problem into several single-objective optimization problems, and accordingly design an improved artificial bee colony algorithm to solve them sequentially. Finally, numerical examples based on the actual data from a subway system in China are conducted to show the effectiveness of the proposed method. Experimental results indicate that substation energy consumption is effectively reduced by using WESS together with a correspondingly optimized timetable. Note that substation energy consumption becomes lower when the total size of WESS is larger, and timetable optimization further reduces it. A set of Pareto optimal solutions is obtained for the experimental subway line—based on which, decision makers can make a sensible trade-off between energy conservation and WESS investment accordingly to their preferences.

scholarly journals Case study of stationary energy storage device in a 3 kV DC traction system

2018 ◽  
Vol 180 ◽  
pp. 02005 ◽  
Author(s):  
Włodzimierz Jefimowski ◽  
Anatolii Nikitenko
Keyword(s):  
Energy Storage ◽  
Storage System ◽  
Energy Storage System ◽  
Energy Utilization ◽  
Storage Device ◽  
Location Selection ◽  
Train Operation ◽  
Traction Substations ◽  
Traction System ◽  
Regenerative Energy

The paper presents the results of economic study of energy storage system (ESS) implemented in 3 kV DC power supply system. Two conceptions of ESS have been investigated: ESS with supercapacitor (SC) and hybrid ESS (HESS) with SC and LFP battery. The investigated locations of energy storage systems are considered among existing traction substations in two railway lines with different density of train operation. The considered aims of energy storage system implementation are decreasing of energy consumption by maximum regenerative energy utilization and reduction of peak 15- min power demand of traction substation. The paper presents a method of regenerative power estimation depending on the location of the considered ESS implementation point. Also the method of optimal location selection of ESS in terms of minimization of Simple Payback Time (SPBT) of investment is presented. Besides the influence of initial cost value as well as energy price on the SPBT value are investigated. The results are compared between two railway lines with different number of trains operating.

scholarly journals Stationary energy storage system in a 3 kV DC – the conception comparison

2018 ◽  
Vol 180 ◽  
pp. 02013
Author(s):  
Włodzimierz Jefimowski
Keyword(s):  
Energy Storage ◽  
Peak Power ◽  
Storage System ◽  
Energy Storage System ◽  
Energy Utilization ◽  
Power Demand ◽  
Dc System ◽  
Traction Substation ◽  
Stationary Energy ◽  
Regenerative Energy

The paper presents the research results of a few different conception of stationary energy storage system in a 3 kV DC system. The most attention is focused on the comparison between two topologies of the ESS: energy storage system with supercapacitor and with supercapacitor and LFP battery. The variants are compared in terms of energy saving and peak power demand reduction. The implementation of ESS with SC results the decrease of active energy drawn from traction substation. Meanwhile the implementation of ESS with SC and LFP battery leads to achieving of two aims - decreasing of active energy consumption by maximization of regenerative energy utilization and reduction of 15 - min. peak power demand of traction substation.

scholarly journals SWIPT-Aware Fog Information Processing: Local Computing vs. Fog Offloading

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3291 ◽  
Author(s):  
Haina Zheng ◽  
Ke Xiong ◽  
Pingyi Fan ◽  
Li Zhou ◽  
Zhangdui Zhong
Keyword(s):  
Information Processing ◽  
Closed Form ◽  
Optimization Problems ◽  
Fog Computing ◽  
Mode Selection ◽  
Optimization Theory ◽  
Access Point ◽  
Power Splitting ◽  
Closed Form Solutions ◽  
Processing Modes

This paper studies a simultaneous wireless information and power transfer (SWIPT)-aware fog computing by using a simple model, where a sensor harvests energy and receives information from a hybrid access point (HAP) through power splitting (PS) receiver architecture. Two information processing modes, local computing and fog offloading modes are investigated. For such a system, two optimization problems are formulated to minimize the sensor’s required power for the two modes under the information rate and energy harvesting constraints by jointly optimizing the time assignment and the transmit power, as well as the PS ratio. The closed-form and semi-closed-form solutions to the proposed optimization problems are derived based on convex optimization theory. Simulation results show that neither mode is always superior to the other one. It also shows that when the number of logic operations per bit associated with local computing is less than a certain value, the local computing mode is a better choice; otherwise, the fog offloading mode should be selected. In addition, the mode selection associated with the positions of the user for fixed HAP and fog server (FS) is also discussed.

Closed-form solutions to a class of H∞-optimization problems

1994 ◽  
Vol 60 (1) ◽  
pp. 41-70 ◽  
Author(s):  
ALI SABERI ◽  
BEN M. CHEN ◽  
ZONGLI LIN
Keyword(s):  
Closed Form ◽  
Optimization Problems ◽  
Closed Form Solutions

scholarly journals Outage Performance of Relay-Assisted Single- and Dual-Stage NOMA Over Power Line Communications

2021 ◽  
Author(s):  
ROOPESH RAMESH ◽  
Sanjeev Gurugopinath ◽  
sami muhaidat
Keyword(s):  
Closed Form ◽  
Communication Systems ◽  
Multiple Access ◽  
Optimization Problems ◽  
Power Line ◽  
Closed Form Solutions ◽  
Power Line Communications ◽  
Optimal Power ◽  
Dual Stage ◽  
Outage Probabilities

<p>In this paper, we analyze the performance of relay-assisted, single-stage (SS) non-orthogonal multiple access (NOMA) and dual-stage (DS) NOMA power line communication systems. Specifically, derive closed form expressions for the outage probabilities of the SS NOMA and DS NOMA schemes. Subsequently, we formulate optimization problems and obtain closed-form solutions for the optimal power allocation coefficients of the SS NOMA and DS NOMA scheme, such that the probability of overall outage is minimized. The accuracy of our analysis and the tightness of the approximations employed are validated through Monte Carlo simulations and numerical techniques. Moreover, we show that the DS NOMA scheme outperforms the SS NOMA scheme, in terms of the overall outage probability.</p>

scholarly journals Outage Performance of Relay-Assisted Single- and Dual-Stage NOMA Over Power Line Communications

2021 ◽  
Author(s):  
ROOPESH RAMESH ◽  
Sanjeev Gurugopinath ◽  
sami muhaidat
Keyword(s):  
Closed Form ◽  
Communication Systems ◽  
Multiple Access ◽  
Optimization Problems ◽  
Power Line ◽  
Closed Form Solutions ◽  
Power Line Communications ◽  
Optimal Power ◽  
Dual Stage ◽  
Outage Probabilities

<p>In this paper, we analyze the performance of relay-assisted, single-stage (SS) non-orthogonal multiple access (NOMA) and dual-stage (DS) NOMA power line communication systems. Specifically, derive closed form expressions for the outage probabilities of the SS NOMA and DS NOMA schemes. Subsequently, we formulate optimization problems and obtain closed-form solutions for the optimal power allocation coefficients of the SS NOMA and DS NOMA scheme, such that the probability of overall outage is minimized. The accuracy of our analysis and the tightness of the approximations employed are validated through Monte Carlo simulations and numerical techniques. Moreover, we show that the DS NOMA scheme outperforms the SS NOMA scheme, in terms of the overall outage probability.</p>

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