Steady-state modelling for the integration of a bi-directional AC–DC–AC flexible power link

Abstract

In the UK, Western Power Distribution (WPD) will be trialling a "Flexible Power Link" (FPL) as part of the Ofgem-funded Low Carbon Networks (LCN) Fund project, Network Equilibrium. The FPL is a power electronic AC-DC-AC device that allows for bidirectional transfer of real power and independent control of reactive power at each side. The trial device will be sited in WPD's network in the south west of the UK, allowing the interconnection of two separate areas of the network that could not normally be interconnected with AC only. This will allow for the balancing of power flows and management of voltages in the networks, enabling increased network utilisation and the integration of new loads and generation. This paper introduces the FPL concept and provides details of the method and results of a study used to understand the FPL's impact on the network, in particular its operational ranges of real power, reactive power, and voltage control set points.

A New Fast-Acting Backup Protection Strategy for Embedded MVDC Links in Future Distribution Networks

“…A fault which resides in either Z2 or Z3 but also within the quadrilateral Z4 characteristic should trip with the time delays associated with Z2 and Z3 to ensure correct discrimination. The logic tripping expression for the fast-acting Z4 area (Z4TRIP) is therefore presented in equation (6). Note that since Z2 is a subset of Z3, a Z2 condition is not required in the tripping logic.…”

“…Embedded medium-voltage direct current (MVDC) links provide DSOs with the capability to control network sections dynamically thus allowing substantial increases in power flows while remaining within the thermal ratings of transformers and conductors [4] [5]. This is being validated through demonstration projects notably in GB, where two DNOs have received regulator funding to deploy multi-megawatt dc demonstrators on their system [6] [7], and in Zhuhai, China [8]. Several vendors have recently began offering MVDC solutions for power distribution applications [9] MVDC technologies have been proposed for shipboard [11], rail traction [12], mining [13], rural low-power/long-distance electrification [14] and for generation collection network [15] [16] applications.…”

A general form of smart contract for decentralized energy systems management

“…DClinks allow the precise control of energy flows between electricity circuits and, combined with smart contracts, offer the potential to clearly delineate responsibility for the operation and control of distinct segments of electricity networks. The potential for DC-links to reduce network costs, through control of active and reactive power set-points is well documented [25][26][27][28][29][30][31] . DC-links also have the potential to decouple networks, and therefore clearly define responsibility for system frequency and, by extension, system stability 26,32,33 .…”