DC Power Grid - Realize Multi-power Supply and Multi-drop Power Receiving

Multi-terminal DC transmission is a stage in the development of DC power grids, which can realize multi-source power supply and multi-drop power receiving. Connect the DC transmission lines to each other on the DC side to form a real DC grid. It has the advantages of greatly reducing the number of converter stations, the converter stations can transmit power independently, the transmission status can be switched flexibly, and the advantages are high reliability.

1. Introduction to DC power grid

With the continued development of renewable energy and the need to upgrade existing grid technologies, the future development of flexible DC transmission will continue to focus on the networking and centralized transmission of wind farms, the interconnection of regional power grids, and the power of city center loads. transportation etc. In many cases, these applications need to realize multi-power input and multi-drop power supply, which requires the use of multi-terminal DC or even DC power grid technology. Multi-terminal HVDC (multi-terminal HVDC) is the initial stage of the development of DC power grids. It is a transmission system that connects more than three converter stations in series, parallel or hybrid, and can realize multi-source power supply and multi-drop power receiving. Since the VSC-HVDC technology has the characteristic of not changing the voltage polarity when the power flow is reversed, it is more suitable for forming a multi-terminal DC system. With the continuous improvement of the manufacturing level of turn-off devices and DC cables, VSC-HVDC will become the most important transmission method in multi-terminal DC transmission and DC grid in terms of high-voltage and large-capacity power transmission. The technologies that need to be overcome in the DC power grid mainly include high-voltage DC circuit breakers, large-capacity DC/DC transformers, and high-voltage DC cables.

Relevant scientific research institutes in Europe have put forward the grand idea of building a networked direct current transmission, that is, the European Super Grid. Through DC networking of renewable energy power generation in a wide area, the complementarity of renewable energy power generation can be fully utilized, large-scale centralized access to renewable energy power generation can be realized, and the utilization rate of renewable energy power generation can be improved.

Multi-terminal DC transmission is a stage in the development of DC power grids, which can realize multi-source power supply and multi-drop power receiving. Connect the DC transmission lines to each other on the DC side to form a real DC grid. It has the advantages of greatly reducing the number of converter stations, the converter stations can transmit power independently, the transmission status can be switched flexibly, and the advantages are high reliability.