A Modular Stacked DC Transmission and Distribution System for Long Distance Subsea Applications

Abstract

A new power transmission and distribution concept-modular stacked direct current (dc) (MSDC)architecture is described. Its main application is subsea oil and gas (O&G) processing, where the marinization of system components, their reliability and retrieval are the most critical requirements. In contrast to conventional HVDC systems, the proposed MSDC technology achieves the required dc transmission voltage by stacking a number of power converter building blocks in series that are easy to marinize. Since each building block is similar to a standard variable frequency drive, the MSDC technology has potentially much lower cost and higher reliability. Moreover, the modular architecture renders the system fault tolerant and capable of operating in a degraded mode. The architecture is also highly reconfigurable as the field matures and the loads evolve over time. A generic subsea field scenario for O&G has been designed and analyzed. The MSDC architecture and associated system control strategy are developed and tested using a real-time simulation platform together with an experimental scaled-down prototype of 160 kVA.Index Terms-High-voltage ac (HVAC), HVDC, oil and gas (O&G), subsea transmission and distribution (T&D), variablespeed drive systems.

Electrification of Subsea Systems Requirements and Challenges in Power Distribution and Conversion

“…Many subsea HVDC structures have been reviewed in [8], [19] with their merits and demerits. Authors in [8] have also proposed a HVDC subsea structure based on the modular conversion, also known as modular stacked direct current trans- [17], (b) Subsea HVAC ring type architecture [19], (c) Subsea HVDC power architecture of Troll A [18], (d) Subsea HVDC power architecture based on ring systems [19].…”

“…This can minimize cost and maintenance involved in the platforms. However, the long step-out distances of the order of 100 km have several problems related to reactive power compensation and the increased power umbilical size if HVAC power transmission and distribution systems are adopted [6]- [8]. Additionally, the voltage levels used for the subsea power transmission can be typically of the order of 36 kV to 100 kV.…”

Modular dual active bridge converter architecture

“…Therefore, in the case of three modules, the controlled quantities are v in1 , v in2 and v o ( Figure 5), while the control variables are the duty cycles d 1 , d 2 and d 3 . Expressions ( 8) and ( 9) relate the controlled quantities with the control variables in the case of three modules, resulting in a MIMO (multiple input, multiple output) system.…”

“…Modular Dual Active Bridge converter architecture Pablo Zumel (1) , Leonardo Ortega (3) , Antonio Lázaro (1) , Cristina. Fernández (1) , Andres Barrado (1), Alberto Rodríguez (2) INTRODUCTION Modular or multi-cell approach is being explored in the last years [1]- [7] as an alternative to increase the voltage and current levels handled by the power converters, increasing efficiency, reducing cost and enhancing output performance like output ripple [1].…”

Current-Fed Multipulse Rectifier Approach for Unidirectional HVDC and MVDC Applications

“…It is important from the operation point of view because it allows the connection of different source or load references (series or parallel). In addition, it enables the fault isolation capability which, for example, is extremely important to avoid the shutdown of large gas and oil production plant [18].…”