RTDS News for Winter 2019

Hardware-in-the-loop testing of the control and protection system for Hokkaido-Honshu HVDC link refurbishment

Guest article by J-Power, Japan

It has been nearly 40 years since the commissioning of the Hokkaido-Honshu HVDC link, which is a bipolar, +/-250kV, 600MW DC system with submarine cables (laid across the Tsugaru Strait) and overhead lines linking Japan’s two major islands. The refurbishment of Pole #1 has already been undertaken, with the analogue controller replaced with a digital system in 2008. The control and protection (C&P) system of Pole #2 has since become obsolete since more than 25 years has passed. This article details the upgrading of the  Pole #2 system with the support of the RTDS Simulator.

The refurbishment work was awarded to the two major Japanese manufacturers who built the original link. One manufacturer was responsible for the C&P system on the Hokkaido side (Japan’s Northern island) and the other was responsible for the Honshu side (Japan’s Main island). Because of this unique multi-vendor system configuration, it was very important to test if the new control systems operated properly together before their installation on both sites.

Hardware-in-the-loop (HIL) testing of the Pole #2 C&P system was conducted using the RTDS Simulator, which is installed at R&D centre of J-POWER, located in Chigasaki city, Kanagawa Prefecture. In Chigasaki, the new telecommunication scheme was also set up  and connected with the control and protection system to establish test conditions which were as close as possible to the real HVDC system in terms of signal flow and transmission time delays.

The simulator represented the main circuit including the AC systems, HVDC overhead lines, cables, valves, and other DC equipment. The tests at  Chigasaki were run from July until the middle of September 2019; more than 550 test cases were carried out to verify functions of the C&P system.

Experience from testing Pole #1 in 2008 encouraged J-POWER to take a more sophisticated approach for Pole #2. In addition to the easy handling of the simulator, numerous fault points were prepared in advance in the test system by adding fault switches and triggering buttons.

This scheme greatly accelerated the test procedure, enabling J-POWER to complete all of the planned tests within the limited period. These intensive tests greatly helped to verify the C&P system functionality and contributed to improve system reliability.

In fact, several control and protection operations were improved before sending the equipment to the both converter stations, including parametric adjustment of pole control blocks. The HIL tests greatly saved time and expenditure related to discussions and parameter adjustments that otherwise would have been made across the Tsugaru Strait. The refurbishment works of Pole #2 will be completed by the end of June 2020.