Enhancing Line Capacity Utilization in Power Transmission System Using Active MVDC Link

Abstract

As a proportion of generation using renewable energy increases in a power system, the need for facility investment is increasing in not only the distribution system but also the transmission system. However, it is inefficient to invest in new equipment to deal with the short peak output of renewable energy generation. For this reason, this paper proposes a method for operating the grid more flexibly, through an optimal operating strategy of the direct current (DC) line at medium-voltage (MV) level, thereby delaying the facility investment in the transmission line. In order to determine the optimal operating point of the converter connected with a DC line, the swarm intelligence-based optimization technique, which can minimize multi-objective function, is used. In addition, in order to overcome the communication dependency of the centralized control, which needs to receive information about the optimal operating point computed by the system operator, this paper proposes a decentralized emergency control (DEC) method in case of a communication fault.

Security-Constrained Day-Ahead Operational Planning for Flexible Hybrid AC/DC Distribution Networks

“…Figure 5. The MVDC configuration is an extension of use of DC links in [6,13], using the same number of VSC stations.…”

“…A dynamic energy management framework considering renewable generations, energy storage systems, flexible demands, and the SOP application was proposed in [12]. In a recent study, [13] introduced a decentralised control of VSC stations to address the issue of communication failure. Like the demonstration project in [6], these studies [7][8][9][10][11][12][13] only considered the interconnection between any two feeders which would limit control (e.g., load transfer capability) to the two feeders.…”

“…In a recent study, [13] introduced a decentralised control of VSC stations to address the issue of communication failure. Like the demonstration project in [6], these studies [7][8][9][10][11][12][13] only considered the interconnection between any two feeders which would limit control (e.g., load transfer capability) to the two feeders. In recent years, the multi-terminal high voltage direct current (HVDC) configurations have been investigated extensively at the transmission level [14][15][16][17][18][19].…”

“…Our contributions in this paper are three-fold: (1) A day-ahead distribution network management framework with flexible demand and DG curtailment to uphold the secure operation during contingencies, (2) an extended security constrained, which covers three stages, pre-contingency, short-term, and long-term post-contingencies, is used to highlight the different remedial action capabilities between slow response (i.e., load tap changer) and fast response (i.e., VSCs) control devices, and (3) a multi-terminal configuration of MVDC is introduced to alleviate the limitations of back-to-back (BTB) or point-to-point (P2P) configurations used in [7][8][9][10][11][12][13] and thus a more flexible network operation can be achieved. The MVDC interface works as a platform for renewable energy integrations at the end of distribution feeders that uses the same number of VSCs as in P2P configuration.…”

Analysis of the behavior of MVDC system in a distribution grid compared to a UPFC system

“…12,13 There are already initiatives in this direction, such as Scottish Power Energy Network's Angle-DC Project, which aims to strengthen the transfer of renewable energy between Anglesey and North Wales mainland (UK) through Europe's first MVDC link. 14,15 Or various studies analyzing the advantages of implementing VDC links in distribution networks, including 16 simulating the behavior of VDC links in order to improve the capacity of the network concerning the incorporation of low-carbon generation technologies and the transition to electric vehicles in a case applied to suburban distribution in Scotland 17 ; which shows the advantages of implementing MVDC links as an alternative to AC lines in the Korean electricity system 18 ; where the first dual terminal VSC-MVDC distribution network built in China is analyzed 19,20 ; where the advantages of the application of these links are shown.…”