Siemens (Norway)

A modular multilevel converter (MMC) is an attractive solution for power conversion without transformers. The MMC consists of cascade connections of floating dc capacitors. In this paper, an adaptive observer design has been proposed to estimate the capacitor voltages from the measurement of arm currents. This work introduces the capacitance value of the cell capacitors as a parameter uncertainty for making the system performance robust with unknown constant parameters. It may be used for predictive control, condition monitoring for capacitors, and diagnosis check for capacitor health. In addition, a pulsewidth modulation (PWM) technique for MMC has been explored. The PWM technique is performed using a carrier-based level-shifted PWM strategy. It does not necessitate the calculation of duty cycles, and can be easily implemented in a DSP. By using the PWM technique, harmonics in the phase voltage is shifted to twice the switching frequency. Theoretical analysis is included in this paper for showing stability and convergence of the proposed observer. Analytical expressions are verified by simulation and experimental results.

A solution to the lack of interoperability between the U.S. Department of Defense (DoD) data communications standards and the NATO standards based on the International Organization for Standardization concept for open systems interconnection is presented. The solution is based on conversion between a common subset of the US DoD Transmission Control Protocol and the ISO Class 4 Transport Protocol at the Transport layer, which is the first layer offering any end-to-end service.

This paper proposes the use of Mixed Integer Linear Programming (MILP) for efficient planning of search missions. The Unmanned Aerial Vehicles (UAVs) taking part in a search mission are assumed to be equipped with cameras or other sensors, with a specified field-of-view below the UAV. The design and implementation of this search algorithm have been made for a general case, such that multiple UAVs with arbitrarily geographically located base stations can take part in the joint search mission and be allocated to different parts of the search area. An algorithm for automatically generation of waypoints inside the defined area has been developed, such that the whole area is covered by the sensors field-of-view when all waypoints have been visited.

In this article the design of an actual and delivered diesel electric system with DC distribution is described. The focus is on the protection philosophy in such a DC distribution system, and how it distinguishes from that in conventional offshore and marine AC distribution systems. The philosophy is based on discrimination. By discrimination it is implied that only the failure affected part is interrupted and then disconnected without interrupting the unaffected part of the system. The Description of the components directly connected to the main switchboard as well as electrical analyses for a vessel with 8 MVA installed electrical power are presented. The ultra fast bus-tie breaker called the Intelligent Load Controller (ILC, pat. pend) is considered to be the heart of the protection system. The ILC is based on IGBTs with additional isolator switches outside. In case of a short circuit failure, the IGBTs break the current before the isolator switches galvanically isolate the switchboards. The ILC is able to interrupt the bus-tie fault current within 10-20 μs, given a low impedance fault. This time is short enough not to reduce the voltage level on the opposite side of the main switchboard capacitor banks. As a consequence, the healthy side of the main switchboard is able to operate continuously - without interruption from the failure event.

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper deals with brush wear and current distribution of carbon brushes on steel slip rings. Measurements of brush wear and brush current have been carried out both in generators in service and in a laboratory test rig. Wear rates increase with increasing brush current only for positive brushes on-site, whereas an evident correlation between brush current and brush wear was found for both polarities in the laboratory. The magnetizing current is, in general, unevenly distributed between the brushes operating in parallel, and the current shifts between different brushes during operation. The current distribution becomes more uneven with increasing mean current density and with increasing circumferential velocity of the slip ring. </para>

Dynamic positioning is an important control feature for an underwater remotely operated vehicle. This paper presents a nonlinear dynamic positioning controller suited for application to vehicles with model uncertainties, operating in environments with unpredictable disturbances, such as an aquaculture net cage. The proposed controller combines the backstepping approach with an adaptation term to ensure robustness. Using Lyapunov theory and Matrosov’s theorem the origin of the closed-loop system is proven to be: (i) globally asymptotically stable when assuming persistency of excitation, and (ii) stable and bounded, with the true position converging to the desired position if there is no persistency of excitation. This paper also presents results from simulations where the proposed controller is contextualized and compared to similar controllers, showing promising results. Finally, as the main result of the manuscript that demonstrates the effectiveness of the proposed control law, an extensive field trial campaign is conducted at a full-scale aquaculture site using an industrial ROV where the proposed controller is successfully tested under realistic operational conditions.

¹⁷⁷Lu-lilotomab satetraxetan is a novel antibody–radionuclide conjugate currently in a phase 1/2a first-in-humans dose escalation trial for patients with relapsed CD37-positive indolent non-Hodgkin lymphoma. The aim of this study was to investigate biodistribution and absorbed doses to organs at risk. <b>Methods:</b> In total, 7 patients treated with ¹⁷⁷Lu-lilotomab satetraxetan were included for dosimetry. Patients were grouped on the basis of 2 different predosing regimens (with and without predosing with 40 mg of lilotomab) and were treated with different levels of activity per body weight (10, 15, and 20 MBq/kg). All patients were pretreated with rituximab. Serial planar and SPECT/CT images were used to determine time–activity curves and patient-specific masses for organs with ¹⁷⁷Lu-lilotomab satetraxetan uptake. Doses were calculated with OLINDA/EXM. <b>Results:</b> The organs (other than red bone marrow and tumors) with distinct uptake of ¹⁷⁷Lu-lilotomab satetraxetan were the liver, spleen, and kidneys. The highest uptake was found in the spleen, with doses ranging from 1.54 to 3.60 mGy/MBq. The liver received 0.70–1.15 mGy/MBq. The kidneys received the lowest dose of the source organs investigated, 0.16–0.79 mGy/MBq. No statistically significant differences in soft-tissue absorbed doses were found between the two predosing regimens. The whole-body dose ranged from 0.08 to 0.17 mGy/MBq. <b>Conclusion:</b> The biodistribution study for patients treated with ¹⁷⁷Lu-lilotomab satetraxetan revealed the highest physiologic uptake to be in the liver and spleen (besides the red marrow). For all treatment levels investigated, the absorbed doses were found to be modest when compared with commonly assumed tolerance limits.

Digital substations, also referred to as modern power grid substations, utilize the IEC 61850 station and process bus in conjunction with IP-based communication. This includes communication with switch yard equipment within the substation as well as the dispatch center. IEC 61850 is a global standard developed to standardize power grid communications, covering multiple communication needs related to modern power grid substations or digital substations. Unlike the legacy communication standards, IEC 60870-5-104 and DNP3, IEC 61850 is specifically designed for IP-based communication. It comprises several communication models and supports real-time communication by introducing the process bus to replace traditional peer-to-peer communication with standard network communication between substation equipment and the switch yard. The process bus, especially Sampled Measured Values (SMV) communication, in modern power grid substations relies on extremely accurate and synchronized time to prevent equipment damage, maintain power grid system balance, and ensure safety. In IEC 61850, time synchronization is provided by the Precision Time Protocol (PTP). This paper discusses the significance and challenges of time synchronization in IEC 61850 substations, particularly those associated with PTP. It presents the results of a controlled experiment that subjects time synchronization and PTP to cyber-attacks and discusses the potential consequences of such attacks. The paper also provides recommendations for potential mitigation strategies. The contribution of this paper is to provide insights and recommendations for enhancing the security of IEC 61850-based substations against cyber-attacks targeting time synchronization. The paper also explores the potential consequences of cyber-attacks and provides recommendations for potential mitigation strategies.

The voltage droop control concept is the most appropriate strategy to provide primary control in multiterminal VSC-HVDC (MTDC) transmission systems. However, due to voltage drops in the dc lines/cables, the primary power balancing is influenced by the dc grid topology and line resistances. This phenomenon is also evident when determining the secondary control strategy in MTDC systems. In this paper, secondary control in MTDC is derived by analogy to the traditional secondary control in an ac grid system. In doing so, the influences of dc line voltage drops are systematically included in the control strategy to restore power flow to pre-disturbance levels at selected dc terminals. The effectiveness of the strategy is demonstrated with the help of a five terminal VSC-HVDC model in the EMTDC/PSCAD simulation tool.

Although many PID tuning approaches are available, it is not easy to find a method that does not require any engineer/operator interference. In this work, we present a fully automated approach for PID tuning based on relay feedback. This method involves sending the relay feedback test data from PLCs (Programmable Logic Controller) into a historian, analyzing the test data using a tuning application to generate a tuning report that contains PID parameters and sending the report back to the operator station to retune the controllers in PLCs. This paper is focused on the following three keys steps: 1) A method to identify persistent steady-state conditions in a control loop using routine operating data because any tuning test is performed when the process is operating at steady state, 2) A novel procedure to implement relay based tuning test, 3) A new model identification method which is a combination of frequency-domain and time-domain analysis. Subsequently, the identified plant model is used to obtain PID tuning parameters based on IMC design. The approach has been tested on an industrial test setup in which all the control loops of the Tennessee Eastman process are controlled by a Siemens PLC. The necessary relay parameters, the hysteresis and relay amplitude, for the test are estimated automatically where interference by an engineer or an operator is not required. The new method for model identification is robust against measurement noises. The proposed method is able to tune the important control loops in the Tennessee Eastman process successfully.

This article is about electric shore power connections in port for vessels in regular service. The main purpose is to reduce emissions from vessels while in port, and for some vessels, to include charging onboard batteries. This article does not cover the needs of vessels under repair, laid-up vessels, and permanently moored vessels.

This paper deals with modeling and control of offshore pipelay operations from a dynamically positioned surface vessel where a nonlinear dynamic beam formulation in three dimensions capable of undergoing shearing, twist and bending is used to model the pipe. This pipe model is coupled with a nonlinear vessel model that has been adopted as a standard for vessel control design and analysis purposes. The complete pipelay system is shown to be input-output passive taking the thruster force as the input and the vessel velocity as the output. A nonlinear controller is applied, and using the passivity condition of feedback connection of two passive systems, the closed loop system is stable. Numerical simulations using both PD and PID controllers illustrate the theoretical results.

Critical infrastructure protection is essential for a well-functioning modern digitized society. Power grid is amongst the most essential critical infrastructures, and stable energy production, transmission and distribution are core part of power grids. The modernization of the power grid and the introduction of smart grids have resulted in increased digitalization and a larger uptake of information technology. Substations are core to the power grid, and safe and secure operation of digital substations are essential for a stable smart grid. To better understand, evaluate and prepare for future cyber-attacks, there is a need to leverage a representative information technology and operational technology testbed that are flexible enough to support testing and evaluation of cyber-attacks, evaluation of vulnerabilities, and that can be used for training and testing of incident response procedures. This paper presents such an infrastructure for digital substations.

The goal of this present study is to monitor process values online using PLC with embedded web server. The system comprises of a three hopper silo with closed loop pneumatic transport line enabling particulate flow, multi sensor suite with Acoustic Emission (AE) sensors, optical level sensors, pressure and flow sensors and for verification purposes a Laser Doppler Anemometer (LDA). Using Siemens S7-300 controller and the CP343-IIT communication controller and Profibus as the medium for sensor networking, a functional remote operated system was realized. This system has been used in various demonstrations within a Thematic Network supported by the European Union, with the acronym THEIERE. The performance of the system, some of the pitfalls encountered in the system integration and the strategy used in designing the remote operation of the system are presented here.

The use of laparoscopic and robotic liver surgery is increasing. However, it presents challenges such as limited field of view and organ deformations. Surgeons rely on laparoscopic ultrasound (LUS) for guidance, but mentally correlating ultrasound images with pre-operative volumes can be difficult. In this direction, surgical navigation systems are being developed to assist with intra-operative understanding. One approach is performing intraoperative ultrasound 3D reconstructions. The accuracy of these reconstructions depends on tracking the LUS probe. Material and methods: This study evaluates the accuracy of LUS probe tracking and ultrasound 3D reconstruction using a hybrid tracking approach. The LUS probe is tracked from laparoscope images, while an optical tracker tracks the laparoscope. The accuracy of hybrid tracking is compared to full optical tracking using a dual-modality tool. Ultrasound 3D reconstruction accuracy is assessed on an abdominal phantom with CT transformed into the optical tracker's coordinate system. Results: Hybrid tracking achieves a tracking error < 2 mm within 10 cm between the laparoscope and the LUS probe. The ultrasound reconstruction accuracy is approximately 2 mm. Conclusion: Hybrid tracking shows promising results that can meet the required navigation accuracy for laparoscopic liver surgery.

Synapses is a project funded under the EU Health Telematics Framework IV Programme. Synapses sets out to solve problems of sharing data between autonomous information systems, by providing generic and open means to combine healthcare records or dossiers consistently, simply, comprehensibly and securely, whether the data passes within a single healthcare institution or between institutions. This paper presents the specification of the Synapses server, the kernel concept of Synapses. It describes the basis in the European prestandard for Electronic Healthcare Record Architecture, the interfaces to the Synapses server and different integration mechanisms for systems providing information to the server. The specification will be verified at a number of validation sites, and the final result will be in the public domain.

The excitation windings of the synchronous generators are generally reliable. However, electrical, mechanical, and thermal stresses that the machine is exposed to during its operation leads to the inter-turn and ground insulation faults. On-line condition monitoring could provide a valuable real-time assessment of the synchronous generator. It could discriminate gradual aggravating defects at an incipient stage before it leads to irreversible and costly damages. On-line monitoring of the air gap magnetic field has been used in different types of electrical machines. However, some concerns should be considered when applying this method to the salient pole synchronous generators (SPSG), especially in the SPSG, with a large number of turns per poles that show less or lack of sensitivity to a fault. This difficulty could be solved by wise locating of the Hall effect sensor, choosing precise sampling rate, re-sampling the data and signal processing approach. In this paper, detailed online monitoring of the air gap magnetic field under the excitation winding defect is proposed. A procedure that could detect the severity and location of the fault-based on different analyzing methods of flux density in no-load and full load is proposed. The nominated approach is examined by using numerical modeling and a experimental test rig with a 100 kVA SPSG. It is proven that the air gap magnetic field spectrum could provide a reliable assessment of the machine under the short circuit fault of the rotor field winding.

Purpose Resource allocation has always been a critical problem with significant economic relevance. Many industries allocate the resources based on classical methods such as overall equipment effectiveness (OEE) and data envelopment analysis (DEA). The lack of OEE factors’ weight, how it is defined, analyzed, interpreted and compared in OEE and selection of unrealistic weights, self-appraisal and disability of complete ranking in DEA are challenges that are possible to occur. These defects may result in unfair allocation of the resources. This study aims to overcome the mentioned weaknesses. Design/methodology/approach In this paper, an approach using a set of various DEA models and Nash bargaining solution (NBS) is designed to solve the resource allocation problem based on OEE, among a set of comparable and uniform DMUs (decision-making units) in a fair way. Findings The results show that a unique Pareto optimal allocation solution is obtained by the proposed DEA–NBS model among the DMUs. This allocation is more acceptable for players, because the allocation results are commonly determined by all DMUs rather than a specific one. Furthermore, the rankings achieved by the utilized methods and TOPSIS (technique for order preference by similarity to ideal solution) are compared by Spearman’s rank correlation coefficient to validate the resource allocation plan. The findings indicate that the DEA–NBS method has the best correlation with the TOPSIS approach. Originality/value To the best of authors’ knowledge, no research has considered the use of DEA and NBS with OEE.

A novel approach to transient stability analysis in multi-terminal high voltage direct current (MTDC) grids is presented in this paper. A symmetrical three-phase fault in an ac grid connected to a rectifier terminal of the MTDC grid causes the power injected into the dc grid to decrease, which in turn leads to a lower dc voltage in the MTDC grid. If dc voltage drops below a critical voltage limit before the ac fault is cleared, then the dc grid becomes unstable and its operation is disrupted. An analytical approach is proposed in this paper to calculate the critical clearing time of a fault in an ac grid behind a rectifier terminal beyond which dc voltage collapse occurs. A five-terminal MTDC grid modeled in EMTDC/PSCAD is used to validate the results obtained with the analytical method.

The different blocks (rectifier, inverter, static bypass switch) in the three phase UPS model B312 are briefly discussed. The input characteristics of the commonly used diode/capacitor rectifier are discussed by analysing the input current waveform with and without a small inductor in the circuit. The source impedance influence on the total performance is stressed separately. In a three phase system with this type of rectifiers connected between each phase and the neutral, the phase current will be added up, not cancelled out, in the Neutral. In the last part of the paper, the input/output current waveforms in a Y/D/Y connected transformer, supplying rectifier load, is shown, and RMS, average and harmonics in the input and output current are calculated. It is shown that with this type of load, the transformer output kVA load will be about 30 % higher than the kVA supplied to the input. The closed loop control block diagram of the B312 inverter is presented, showing the common (dc) slow regulator controlling three individual (ac) fast regulator loops.