Rubber Tyred Gantry Crane Research Articles

Design, modelling, control and techno-economic evaluation of a fuel cell/supercapacitors powered container crane

This paper presents a “full green” version of a rubber tyre gantry (RTG) crane with a fuel cell (FC) unit and supercapacitors (SCs) as energy storage system (ESS), instead of using the conventional RTG powered by a diesel engine. The SCs provide the required high current peaks and power demands when accelerating the load in the hoisting-up movement. Once the power demand reaches a steady level (hoist up constant speed), the FC provides the energy needed for the rest of the movements. The SCs are also charged when the hoist down movement is taking place. In this case, the regenerative energy can be stored in the SCs instead of being burnt in the braking resistors as in the conventional RTG crane. The new hybrid powertrain based on FC and SCs is designed and evaluated from the real driving cycle of the RTG crane. Simulation results, which include a comparative study with the current configuration of the RTG crane (powered only by diesel engine), demonstrate the technical viability of the RTG crane powered by FC and SCs. This hybrid powertrain is more expensive than the diesel powertrain, but more energy-efficient, and a better solution from the environmental point of view.

Energy efficiency and CO2 emissions of port container terminal equipment: Evidence from the Port of Valencia

Energy efficiency has emerged as a key point in port industry because of different factors such as the adoption of stronger environmental regulations and the increasing pressure of the local community on the surrounding ports. As gathering operational data from port terminals can be difficult due to privacy, studies on emissions and energy efficiency of these terminals are scarce. The following research provides key information about the real energy consumption and CO2 emissions of one of the most relevant container terminals in the Mediterranean area, located in Valencia, Spain. The results show that yard terminal tractors and rubber tyred gantry cranes (RTGs) are the main emission sources, accounting for 68.1% of the terminal's total CO2 emissions. After identifying the equipment responsible for the environmental problem, two solutions aimed at improving the energy efficiency of the terminal have been studied: the retrofitting of RTGs cranes and the replacement of terminal tractors powered by fuel for a new liquefied natural gas tractor, which contributed to a large reduction of CO2 emissions. Additionally, the present research explores the different policies at the disposal of port authorities in order to foster the implementation of solutions aimed at mitigating the environmental externalities by terminal operators.

A Comparative Study of Energy Storage Systems and Active Front Ends for Networks of Two Electrified RTG Cranes

The global consumerism trend and the increase in worldwide population is increasing the need to improve the efficiency of marine container transportation. The high operating costs, pollution and noise of the diesel yard equipment is leading sea ports to move towards replacing diesel RTG cranes with electric Rubber Tyre Gantry (RTG) cranes which offer reduced environmental impact and higher energy efficiency. However, ports will require smarter solutions to meet the increased demand on the electrical distribution network due to the electrification of RTGs. This paper aims to highlight the peak demand problem in the two electrical cranes network and attempts to increase the energy saving at ports by using two different technologies: Energy Storage System (ESS) and Active Front End (AFE). This article introduces one of the first extensive investigations into different networks of RTG crane models and compares the benefits of using either AFE or ESS. The proposed RTG crane models and network parameters are validated using data collected at the Port of Felixstowe, UK. The results of the proposed RTG cranes network show a significant peak demand reduction and energy cost saving.

Stochastic optimal energy management system for RTG cranes network using genetic algorithm and ensemble forecasts

Abstract In low voltage networks, Energy Storage Systems (ESSs) play a significant role in increasing energy cost savings, peak reduction and energy efficiency whilst reinforcing the electrical network infrastructure. This paper presents a stochastic optimal management system based on a Genetic Algorithm (GA) for the control of an ESS equipped with a network of electrified Rubber Tyre Gantry (RTG) cranes. The stochastic management system aims to improve the reliability and economic performance, for given ESS parameters, of a network of cranes by taking into account the uncertainty in the RTGs electrical demand. A specific case study is presented using real operational data of the RTGs netwrok in the Port of Felixstowe, UK, and the results of the stochastic control system is compared to a standard set-point controller. In this paper, two forecast data sets with different levels of accuracy are used to investigate the impact of the crane demand forecast error in the proposed ESS control system. The results of the proposed control strategies indicate that the stochastic management system successfully increases the electric energy cost savings, the peak demand reductions and successfully outperforms a comparable set-point controller.

Management of cargo flow processes at a maritime terminal container with the use of information systems of the TOS type

The article explains and discusses the logistic processes occuring inside a maritime container terminal. The processes relate to import as well as export of the goods. A brief characteristisc of the handling equipment, such as: Automated Guided Vehicle, Rail Mounted Gantry Crane, Rubber Tyred Gantry Crane and Ship-to-shore crane has been carried out. During the internal transportation of the containers within the terminal, all the procedures must integrate together. Due to large number of processes taking place in terminals, they base on operating systems such as: Terminal Operating Systems. The characteristics of TOS operating in polish container terminals has been performed. The TOS are IT tools facilitating management of the terminal and leading to improve its efficiency and effectiveness. The purpose of the article is to highlight advantages and benefits of using systems such as TOS..

Narrow Band State of Charge (SOC) Control Strategy for Hybrid Container Cranes

This paper evaluates possibility of using a new hybrid system based on variable speed diesel generator (VSDG), Li-ion battery bank and supercapacitor bank (SC) for a rubber tire gantry crane (RTGC) used in container terminals. Existing commercial hybrid systems face difficulties producing high efficiencies, higher life span, and lower initial investment cost due to inheriting characteristics of batteries and supercapacitors. In the proposed power system, a variable speed diesel generator act as the principal energy source, while a Li-ion battery bank and SC bank act as an energy storage system. The battery supports the diesel generator during steady demand and further, it absorbs a part of energy during regeneration. The energy management strategy, control the power flow from different sources while maintaining battery state of charge (SOC) level within a narrow band. Unlike most battery systems, this narrow band operation of battery system increases its life span while reducing capacity fade. The originality of this study can be emphasized from this narrow band SOC control technique. Simulation results for real operational load cycles are presented showing a stable system operating under defined current limits which can enhance lifetime of battery system and increase fuel saving by downsizing 400 kW constant speed diesel generator to 200 kW VSDG.

The Dynamic Power Control Technology for the High Power Lithium Battery Hybrid Rubber-Tired Gantry (RTG) Crane

In order to ensure the operation safety of the lithium battery hybrid rubber-tired gantry (RTG) crane, the dynamic power control of the lithium battery hybrid RTG crane is studied. This paper introduces the construction and switching modes of the lithium battery hybrid RTG crane. The generator set will not turn on / off frequently using the power management strategy with max on and off , especially in the hybrid system with high-capacity battery and small size of diesel engine generator set. The high-power lithium battery is a better choice for RTG because it reduces emissions on the port. The dynamic model of the hybrid RTG crane is established, and the operation characteristics in different modes are analyzed. The safe operation is realized through the coordinated control load power, battery power, and the diesel-generator power. The warm-up time and cool down time of generator set are considered in the power management strategy with max on and off for a series hybrid system for the first time. The hybrid RTG crane characteristic and the energy saving are verified through the experimental data. The cost of charging the battery is analyzed, revealing that the new RTG saves 70% compared to the conventional RTG crane.

Sizing an Energy System for Hybrid Li-Ion Battery-Supercapacitor RTG Cranes Based on State Machine Energy Controller

Ports and container terminals play an important role in the global logistics system. Handling containers inside container terminals and rail terminals are mostly carried out by rubber tire gantry (RTG) cranes. These cranes have quite different power profile compared to hybrid vehicles. They have a broad power demand, varying from 10kW to 350kW, 170kW regenerating power, and a maximum of 30kW auxiliary power. The high peak demand due to the acceleration of hoist drivetrain determines the prime mover (diesel generator) capacity. This capacity is highly over-rated when comparing with crane's average power demand. Such power profiles having high peak power to average power ratio can be supplied through hybrid systems which can downsize the diesel generator, improve fuel efficiency, reduce CO 2 emissions, and reduce maintenance cost. In this study, a hybrid energy source is presented for an RTG crane. The hybrid energy source comprises a Lithium-ion battery bank, supercapacitor (SC) bank connected to the DC-link through bi-directional DC/DC converters, and a downsized variable speed diesel generator (VSDG) connected to the DC-link through an active rectifier. The narrowband operation of the battery bank helps to increase the healthy life of the battery system reducing risk due to unhealthy conditions during faults and abnormal situations. In this paper, the sizing of a hybrid energy system controlled by a state machine controller is presented. Unlike traditional optimization-based sizing techniques, unique features of demand profile, operating environment, system redundancy, backup operation, readily available components, and specific features of state machine controller were highly considered which differentiate the method of sizing from others.

Carbon-efficient deployment of electric rubber-tyred gantry cranes in container terminals with workload uncertainty

Rubber-tyred gantry cranes are one of the major sources of carbon dioxide emissions in container terminals. In a move to green transportation, the traditional diesel powered cranes are being converted to electric ones. In this paper, we study the deployment of electric powered gantry cranes (ERTGs) in container terminal yards. Cranes always move in-between blocks to serve different workload. ERTGs use electricity for most movements but switch to diesel engines to allow inter-block transfers between unaligned blocks. We exploit this feature and propose to consider simultaneously the CO2 emissions and workload delays to develop carbon-efficient deployment strategies. Moreover, unlike previous works we consider the workload uncertainty, and model the problem as a two-stage stochastic program. A sample average approximation framework with Benders decomposition is employed to solve the problem. Multiple acceleration techniques are proposed, including a tailored regularised decomposition approach and valid inequalities. A case study with sample data from a major port in East China show that our proposal could reduce significantly CO2 emissions with only a marginal compromise in workload delays. Our numerical experiments also highlight the significance of the stochastic model and the efficiency of the Benders algorithms.

Hybrid powertrain, energy management system and techno-economic assessment of rubber tyre gantry crane powered by diesel-electric generator and supercapacitor energy storage system

This paper describes and evaluates a hybrid propulsion system based on diesel generator and supercapacitors (SCs) as energy storage system (ESS) for a rubber tyre gantry (RTG) container crane, which currently operates within the yard of the Algeciras port terminal (Spain) powered by diesel electric generator for supplying the electric drives and motors (hoist and trolley). The SCs, which are connected to the DC bus through a bidirectional DC/DC converter, are controlled by a control strategy based on the DC-bus voltage. The SCs reference current is limited depending on their state-of-charge (SOC). All main components and control strategy of the RTG crane are modelled and simulated in SimPowerSystems. The current and hybrid configuration are simulated and compared under the real working cycle of the RTG crane. The results show the technical viability, the validity of the proposed control strategy, the improvements in the energy efficiency and diesel fuel consumption, and the economic viability of the hybrid propulsion system for the RTG crane.

Energy management systems for a network of electrified cranes with energy storage

An Energy Storage System (ESS) is a potential solution to increase the energy efficiency of low voltage distribution networks whilst reinforcing the power system. In this article, energy management systems have been developed for the control of an ESS connected to a network of electrified Rubber Tyre Gantry (RTG) cranes. Considering the highly volatile crane demand behaviour and uncertainty in the RTG crane demand prediction as a nonlinear optimisation problem, this paper presents and verifies an optimal energy control strategy based on a Stochastic Model Predictive Control (SMPC) algorithm. The SMPC controller aims to improve the reliability and economic performance of a network of RTG cranes, under a given ESS and network specification. A specific case, using different ESS locations, is presented and the results of the proposed SMPC and MPC control models are compared to a set-point controller using data collected from an instrumented electrified RTG cranes at the Port of Felixstowe, UK. The results indicate that the SMPC controller successfully reduce electrical energy costs, the peak demand and outperforms each of the presented control techniques.

ANALISIS PERHITUNGAN DAN SIMULASI TEGANGAN TWIST LOCK RUBBER TIRED GANTRY CRANE (RTGC) KAPASITAS ANGKAT 35 TON DENGAN MENGGUNAKAN SOFTWARE AUTODESK INVENTOR 2014

Rubber Tyred Gantry Crane (RTGC) is a transport lifting equipment which serves to move the containers from head truck to the container terminal or vice versa and as a regulator of the composition of the container stacks. Twist lock is the most important components that are on Rubber Tired Gantry Crane (RTGC). This component is located on the four corners of the spreader. Twist lock function to lock the container at the time of appointment. And load the container will be distributed evenly. This study and simulation to calculate the voltage that occurs at the twist lock with variations in loading and adjusts the nature of the material used. The magnitude of the voltage is done with theoretical calculations and simulated using Autodesk Inventor 2014 software. Based on the research results, the loading of 20 tons, 30 tons and 40 tons with theoretical calculations obtained voltage value is 94705,33 kPa, 142057,98 kPa dan 189410,66 kPa. The simulation results obtained von mises stress value 91900 kPa, 137800 kPa dan 183800 kPa.

Day-ahead industrial load forecasting for electric RTG cranes

Given the increase in international trading and the significant energy and environmental challenges in ports around the world, there is a need for a greater understanding of the energy demand behaviour at ports. The move towards electrified rubber-tyred gantry (RTG) cranes is expected to reduce gas emissions and increase energy savings compared to diesel RTG cranes but it will increase electrical energy demand. Electrical load forecasting is a key tool for understanding the energy demand which is usually applied to data with strong regularities and seasonal patterns. However, the highly volatile and stochastic behaviour of the RTG crane demand creates a substantial prediction challenge. This paper is one of the first extensive investigations into short term load forecasts for electrified RTG crane demand. Options for model inputs are investigated depending on extensive data and correlation analysis. The effect of estimation accuracy of exogenous variables on the forecast accuracy is investigated as well. The models are tested on two different RTG crane data sets that were collected from the Port of Felixstowe in the UK. The results reveal the effectiveness of the forecast models when the estimation of the number of crane moves and container gross weight are accurate.

Optimal Energy Management and MPC Strategies for Electrified RTG Cranes with Energy Storage Systems

This article presents a study of optimal control strategies for an energy storage system connected to a network of electrified Rubber Tyre Gantry (RTG) cranes. The study aims to design optimal control strategies for the power flows associated with the energy storage device, considering the highly volatile nature of RTG crane demand and difficulties in prediction. Deterministic optimal energy management controller and a Model Predictive Controller (MPC) are proposed as potentially suitable approaches to minimise the electric energy costs associated with the real-time electricity price and maximise the peak demand reduction, under given energy storage system parameters and network specifications. A specific case study is presented in to test the proposed optimal strategies and compares them to a set-point controller. The proposed models used in the study are validated using data collected from an instrumented RTG crane at the Port of Felixstowe, UK and are compared to a standard set-point controller. The results of the proposed control strategies show a significant reduction in the potential electricity costs and peak power demand from the RTG cranes.

Sizing of Energy System of a Hybrid Lithium Battery RTG Crane

Rubber tyred gantry (RTG) cranes are an important piece of transport equipment in ship and rail container terminals. They have a diversified power demand, for example, peak powers of 292-kW driving, 178 kW regenerating, and 7-kW idle power. The high peak power demand determines the system prime mover (internal combustion engine) rating, which is highly over-rated for the crane average energy requirements. Such a variation in peak to idle power demand favors a hybrid power solution which, given appropriate design, can yield significant gains in fuel or energy usage and, importantly, reductions in local emissions, thus improving air-quality. In this study, a hybrid energy source for an RTG crane is presented. The hybrid energy source comprises of a lithium battery and a down-sized diesel-generator connected to the dc link through an active front end unit. While other systems have been previously proposed, the system presented here utilizes a smaller diesel-generator, thus reducing plant and fuel consumption. In addition, the battery connects directly to the dc link reducing system power electronics while improving battery response and efficiency. Experimental results from a full-size evaluation system are presented showing a 57% reduction of fuel consumption compared to a conventional RTG crane system.

Control of Energy Storage

In the attempt to tackle the issue of climate change, governments across the world have agreed to set global carbon reduction targets. [...]

Hybridization of rubber tired gantry (RTG) cranes

Since there is a growing interest worldwide in reducing pollution from sea transport and sea ports activities, one of the biggest issues is to reduce energy consumption and emissions from ground transportation within ports to cranes and other logistic activities. In particular, Rubber Tired Gantry cranes with Diesel engine coupled with electric drive normally brakes the lowering of the container electrically, by dissipating the electric power in resistive loads. This means that energy is consumed to lift the containers and dissipated when it could be recovered, when lowering the load. Thus, one possibility is to recover that energy in a storage system, based on supercapacitors or lithium batteries. This paper starts from experimental measurements conduced on a RTG crane operating in an Italian port. After evaluating real power and energy flows, an appropriate powertrain architecture based on the utilisation of such storage systems was selected, and components properly sized to increase the overall system efficiency. To analyse the different variants and optimize the energy management strategy, a simulation model realised in Modelica language has been used, in order to investigate the cost-effectiveness of the different proposed solutions.

Analysis of energy usage for RTG cranes

The purpose of this paper is to study and analyse the energy that is used by the various motors of a crane of the Rubber Tyred Gantry type. For this reason a single Rubber Tyred Gantry (RTG) crane has been instrumented at port of Felixstowe and data has been collected during normal operation for eight days. This data has been analysed in terms of active and idle modes and also in terms of energy usage by the various motors. From this analysis it is possible to determine that on average about half of the energy consumed is potentially recoverable. It is also estimated that the recovery of this proportion of energy could lead to savings of 32,600 L of fuel and 8100 tonnes of CO2 per year at Port of Felixstowe.

Reducing Fuel Consumption Using Flywheel Battery Technology for Rubber Tyred Gantry Cranes in Container Terminals

Flywheel Energy Storage System (FESS) is used as an energy regeneration system to help with reducing peak power requirements on RTG cranes that are used to load or unload container ships. Nevertheless, with the use of FESS, Port Operator can deploy undersized generator for new RTG as this will further reduce fuel consumption. This paper presents the investigation of the amount of energy and fuel consumption that can be reduced in Rubber Tyred Gantry (RTG) cranes in container terminals by the use of simulation. In addition, Variable Speed Generator is integrated to the simulation-hybridized RTG. Simulation results reveal that the total energy saving exceeded 30% relatively to conventional RTG. A hardware-in-loop system is introduced for the purpose of validating the simulation results. The hardware components procured include a FESS, a Variable Frequency Drive (VFD) and brake resistors.

Scheduling optimization of yard cranes with minimal energy consumption at container terminals

This paper proposes a novel integer programming model to solve optimal problem of yard crane scheduling with minimal energy consumption at container terminals from the low carbon perspective. The traditional approaches for optimal crane scheduling focus only on crane moving distance without considering the total energy consumption of yard cranes. In this paper, an optimal model is built with consideration of such key factors as the crane moving distance, turning distance and the practical operation rules, which are directly related to the total energy consumption. In accordance with the general kind of handling system at container terminals in China, an integer programming model is proposed to optimize scheduling of yard cranes at container terminals with the purpose of minimizing the total energy consumption of the rubber-tyred gantry cranes. Then, on the basis of the actual operational data of the Shanghai Yangshan Deep Water Port (SYDWP), the container volume of each block is calculated and used to solve the model. Finally, computational experiments are proposed to illustrate and validate the solutions for yard crane scheduling.