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Offshore substations are important sustainable power infrastructures subjected to strong vibrations induced by complex environmental excitations such as wind, waves, and currents. To protect the structures and expensive facilities, lightweight vibration control devices are highly desirable in offshore substations. With a high-performance energy dissipation device, the inerter, the conventional Tuned Mass Damper (TMD) is upgraded for lightweight vibration control. The optimal parametric design and performance evaluation of single- and double-tuned vibration control devices is performed based on the H-norm criteria. The corresponding equivalent mass ratios of both single- and double-tuned vibration control devices are summarized and formulated in a systematical manner. Finally, the presented optimal design formulas, equivalent mass ratios, and control performances are validated by vibration control analyses on a practical offshore substation. The results show that inerter-based vibration control devices can be effectively equivalent to a TMD, with the equivalent mass ratio. The double-tuned inerter-based device could save 25% mass compared to a TMD. With a Tuned Mass Damper Inerter (TMDI), the responsibility for the mass could be shared with dual-end connected inerters. Meanwhile, the Tuned Viscous Mass Damper (TVMD) completely replaces the mass block with an inerter, which has a superior lightweight vibration control performance. [ABSTRACT FROM AUTHOR]

Condition-based maintenance is very desirable for minimizing the maintenance and failure costs of power systems without sacrificing reliability. A systematic approach including an adaptive maintenance advisor and a system maintenance optimizer is proposed here for effectively handling the operational variations and uncertainties for condition-based maintenance. First, the maintenance advisor receives and implements the maintenance plans for its key components from the system maintenance optimizer, which optimizes the maintenance schedules with multi-objective evolutionary algorithm, considering only major system variables and the overall system performance. During operation, the offshore substation will experience continuing ageing and shifts in control, weather and load factors, measurement and human judgment detected from the connected grid and all other equipments with uncertainties. Then, the advisor estimates the changes of reliability indices due to operational variations and uncertainties of its key components by hierarchical fuzzy logic and sends the changes back to the maintenance optimizer. The maintenance optimizer will upgrade the load-point reliability and report any drastic deterioration of reliability within each substation, which may lead to re-optimization of the substation's maintenance activities for meeting its desired reliability. The offshore substation connected to a medium-sized onshore grid will be studied here to demonstrate the ability of this proposed approach in dealing with uncertainties in the implementation of maintenance with significant reduction of computational complexity and rule base.

The construction of deep-sea and offshore wind farms is key to the development of offshore wind power. Since the forms of bottom supporting structures and their installation methods greatly affect the overall cost of electrical platform, the latest developments in this filed were reviewed, based on which a novel integrated floating method was introduced. First, by incorporating the advantages of the integrated offshore wind turbine and the installation method for suction bucket foundation, the idea of integrated floating and quick installation based on a four-bucket jacket foundation was proposed. Second, the process of integrated wet towing of the four-bucket jacket foundation was described, which was further verified via indoor model experiments and numerical simulations. Results show that under 2 m wave height and level 5 sea conditions, the proposed four-bucket jacket foundation can be wet towed and floated at a speed of 5 knots under the optimum draft depth. [ABSTRACT FROM AUTHOR]

[Introduction] Sea transportation is one of the governing conditions for the structural design of topside modules, the accuracy of load input directly affects the structural design of the topside. At present, domestic sea transportation design generally ignored the influence of hull deformation in topside design, which considers the hull as a rigid body, this assumption is not in line with the actual situation, it is necessary to analyze the influence of hull deformation on sea transportation design of the topside module. [Method] Firstly, the domestic sea transportation analysis methods were introduced. Then, combined with the classification society specification, the hull deformation was theoretically expounded, and how some multinational companies consider the influence of hull deformation on sea transportation design of topside module was introduced, the current sea transportation design method was improved. [Result] Based on real project calculation, it proves that structural stress is seriously small without considering the hull deformation load. With the development of marine engineering, we need to pay more attention to the influence of hull deformation on sea transportation design. [Conclusion] This paper explains the risk of traditional sea transportation design and provides an important basis for improving sea transportation design methods.

[Introduction] This paper aims to reduce the risk of shutdown or heavy loss of regional oil fields caused by platform fire in offshore substation. [Method] Taking an offshore substation as an example, the adaptability and application scope of high pressure water mist fire extinguishing system were analyzed. Through the benchmarking analysis and calculation of domestic and foreign specifications and equipment parameter characteristics, the parameter selection and application methods of different fire extinguishing types of electrical equipment in offshore substations were proposed. [Result] The study shows that the local application system of high pressure water mist is suitable for the oil-containing electrical primary equipment and large room, and the spray intensity shall be not less than 1.5 L/(min·m2). When taking into account the equipment waterproof grade and equipment heat dissipation is not economical, heptafluoropropane fire extinguishing system should be used for electrical secondary equipment. [Conclusion] The research results can provide reference for the construction of fire extinguishing system in offshore substation.

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Copyright of Southern Energy Construction is the property of Southern Energy Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Introduction] In this paper, strength and toughness analysis under earthquake for the whole model of offshore substation is presented, performance of offshore substation is analyzed under effect of earthquake in the design reference period different exceedance probabilities. [Method] The seismic performance was evaluated by the results from response spectrum method for strength analysis and the pushover analysis method for toughness analysis. [Result] By analyzing performance of substation jacket platform and accessory structures, the seismic performance of the structure meets the requirement of "No damage under minor earthquake, Repairable under moderate earthquake, No collapsing under major earthquake" considering sufficient safety factor. [Conclusion] It shows that the offshore substation has good seismic performance.

Power systems are crucial for low-carbon energy applications. Condition maintenance plays a vital role in reducing the maintenance cost of renewable power systems without sacrificing system reliability. This paper proposes a hybrid method to effectively deal with the operational changes and uncertainties of state maintenance within the power system of renewable energy applications. Specifically, a multi-objective evolutionary algorithm is first adopted to maintain key components when only considering system variables and overall performance. During operation, numerous variations in offshore substations are detected from power grids and other equipment, such as continuous aging, weather, load factors, measurement, and human-judgment factors. Then, the advisor implements a system optimization maintenance plan in the substation, which can predict changes in load reliability based on the type 2 fuzzy logic and hidden Markov model technology. The reliability of the load point of each substation would also be obtained. Illustrative results indicate that these serious deteriorations would cause substation for the re-optimization maintenance and optimization activities to meet expected reliability. Through connecting an offshore substation to a medium-sized offshore substation, the uncertainties in condition-based maintenance of renewable energy applications can be well handled.

In Offshore Substations (OSs), using High Temperature Superconducting (HTS) transformers instead of conventional power transformers to reduce operational and construction limitations such as weight, capacity, marine pollution, and future planning can be considered as desirable. HTS transformers can reduce operating system costs in wind power plant development programs. However, OSs have specific operating conditions in fault mode that should be considered in the design HTS transformers. In this paper, a 250 MVA 33/220 KV HTS transformer is designed, and electromagnetic analysis is done in normal conditions to calculate AC loss and thence to design the cooling system. The second step, thermo-flow analysis is done by Finite Element Method (FEM) to calculate the temperature distribution of the windings. Increasing turbulence of inlet flow and creating a porous coating on the tapes are used in this transformer to increase the heat-transfer rate. lastly, the specifications of the HTS transformer are compared with the conventional transformer to give useful information to OS designers to investigate using novel construction ideas such as floating OS by HTS transformer. [ABSTRACT FROM AUTHOR]

The current development of electric power industry in Poland, especially in the field of renewable energy sources, including wind power, brings about the need to introduce legislation on new work environment. The development of occupational safety and health (OSH) regulations that must be met by new workplaces, such as offshore substations becomes necessary in view of the construction of modern offshore wind power plants – offshore wind farms. Staying on offshore substation is associated with an increased exposure to harmful health factors: physical, chemical, biological and psychophysical. The main sources of health risks on offshore substations are: temperature, electromagnetic field, noise from operating wind turbines, direct and alternating current, chemicals, Legionella bacteria and social isolation of people. The aim of this article is to draw attention to the problem of offshore substation workers’ exposure to harmful factors and to present methods of preventing and reducing the risk-related adverse health effects. In this paper, there are identified and described risks occurring on offshore substations (fire, explosion, lightning, accidents at work). Some examples of the means and the methods for reducing the negative impact of exposure on the human health are presented and discussed. The article also highlights the need to develop appropriate laws and health and safety regulations concerning the new working environment at the offshore substations. The review of researches and international standards shows that some of them can be introduced into the Polish labor market. Med Pr 2016;67(1):51–72

Offshore renewable energy, and in particular the offshore wind energy sector, is still developing in many countries around the world. Wind offshore projects are characterized by the need to build offshore electric power transmission infrastructure. Offshore substations are a key element of submarine electric power transmission systems. Due to the environmental conditions, an offshore substation is constructed as an indoor facility located on a platform. Depending on the offshore wind farm capacity, there are various solutions for platform and substructure designs used for the substation. Numerous economic and technical analyses indicate a significant potential for the development of offshore wind energy in Poland. By 2030, this potential is set at 6 GW of installed capacity, taking into account 2.2 GW of power included in the connection agreements being concluded. The main objective of this paper is to present the prospects for the development of offshore wind energy in Poland, and to describe the various offshore substation solutions and the different aspects of substation operation. Offshore wind energy resources and power capacity are also presented. Moreover, solutions for offshore substation platforms, electrical equipment and layout, functions of offshore substations in the power systems and offshore substation designs are described. [ABSTRACT FROM AUTHOR]

Offshore wind power is a kind of clean and renewable energy. In recent years, offshore wind power has been exploited more and more widely. With the hub of power collection of offshore wind farm, the offshore substation becomes an important facility for offshore wind power transmission and transformation. In this paper, the current situation of the foundation and installation mode of offshore wind farm substation are introduced, with emphasis on an integral wet-towing method based on a wide-shallow bucket jacket foundation (WSBJF). Firstly, based on the advantages of the integral installation mode of offshore wind power and the composite bucket foundation, the WSBJF of offshore substation is proposed. Secondly, the wet-towing method and the corresponding construction processes of WSBJF are elaborated, and the feasibility of the wet-towing method is verified by the indoor model experiments and numerical simulation analysis. Finally, with the help of the model experiments and numerical simulation, the effects of draft depth, wave height and wave period on foundation stability and dynamic response are investigated. The results show that it is feasible to carry out long distance wet-towing of the foundation under the condition of level 5 wind and waves. WSBJF has a certain self-floating ability, which can meet the wet-towing stability requirements without upper platform. Reducing draft depth and increasing wave height will reduce the stability of WSBJF during wet-towing. Under the premise of a certain draft depth of the foundation, when the wave period is close to the natural period of the WSBJF, the WSBJF will be rocked greatly. For example, the pitch angle of the WSBJF at 14 s wave period is 56 times that at 6 s wave period. • A wide-shallow bucket jacket foundation for offshore substation or converter station is developed. • An integral wet-towing method based on WSBJF is proposed. • The stability and resistance of WSBJF during the integral wet-towing are quantified. [ABSTRACT FROM AUTHOR]

Abstract: A marine substation for a grid-connected wave power plant has been designed and constructed at Uppsala University. The measurement system for the substation has been developed from basics, and the procedure is described in this article. Subsea electrical installations set high constraints on the control and data acquisition systems used, and traditional GSM networks and GPS time synchronization are difficult and inefficient. These circumstances exclude many well-proven methods to be utilized. A compactRIO-based system, with integrated real-time controller and Field-Programmable Gate Array chip, is chosen as most suitable for this task. The system is designed to meet the special requirements encountered in this unusual application, including large data sampling, grid connection control and protection systems. The system is communicating to shore via a subsea copper cable and single-pair high-speed digital subscriber line modems. The design was successful and full-fills all the system requirements. The aim of the article is to provide future researchers with a good design and implementation procedure for setting up large measurement systems. [Copyright &y& Elsevier]

Smart grid provides the technology for modernizing electricity delivery systems by using distributed and computer-based remote sensing, control and automation, and two-way communications. Potential benefits of the technology are that the smart grid's central control will now be able to control and operate many remote power plant, optimize the overall asset utilization and operational efficiently. In this paper, we propose an innovative approach for the smart grid to handle uncertainties arising from condition monitoring and maintenance of power plant. The approach uses an adaptive maintenance advisor and a system-maintenance optimizer for designing/implementing optimized condition-based maintenance activities, and collectively handles operational variations occurring in each substation. The system-maintenance optimizer generates the initial maintenance plans for each substation with multiobjective optimization by considering only the design or average operational conditions. During operation, the substation will experience aging, control shifts, changing weather and load factors, and uncertain measurements. Residing on each host substation, the maintenance advisor will assess the adequacy of initial maintenance plans; and estimate the reliability changes caused by operational variations on the substation using a hierarchical fuzzy system. The advisor will also alert the maintenance optimizer on whether a reoptimization of its maintenance activities should be initiated for meeting the overall grid-reliability requirement. Three scenarios will be studied in this paper, which will demonstrate the ability of the proposed approach for handling operational variations occurring in an offshore substation with manageable computational complexity. [ABSTRACT FROM PUBLISHER]

The current development of electric power industry in Poland, especially in the field of renewable energy sources, including wind power, brings about the need to introduce legislation on new work environment. The development of occupational safety and health (OSH) regulations that must be met by new workplaces, such as offshore substations becomes necessary in view of the construction of modern offshore wind power plants - offshore wind farms. Staying on offshore substation is associated with an increased exposure to harmful health factors: physical, chemical, biological and psychophysical. The main sources of health risks on offshore substations are: temperature, electromagnetic field, noise from operating wind turbines, direct and alternating current, chemicals, Legionella bacteria and social isolation of people. The aim of this article is to draw attention to the problem of offshore substation workers' exposure to harmful factors and to present methods of preventing and reducing the risk-related adverse health effects. In this paper, there are identified and described risks occurring on offshore substations (fire, explosion, lightning, accidents at work). Some examples of the means and the methods for reducing the negative impact of exposure on the human health are presented and discussed. The article also highlights the need to develop appropriate laws and health and safety regulations concerning the new working environment at the offshore substations. The review of researches and international standards shows that some of them can be introduced into the Polish labor market., (This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.)