China Develops Largest 750kV 140Mvar Stepped-Controlled Reactor

Chinese reactor manufacturer successfully completed all tests in one go for the nation’s largest-capacity 750 kV, 140 Mvar stepped-controlled shunt reactor developed for the Turpan–Bazhou–Kuche II Circuit 750 kV transmission and transformation project. The successful completion of these tests marks a new breakthrough in the core manufacturing technology of 750 kV reactors by the Chinese manufacturer, pioneers a new field for 750 kV stepped-controlled shunt reactors in China, and lays a solid foundation for the future development of 1000 kV stepped-controlled shunt reactors.

The Chinese reactor manufacturer has consistently maintained a leading position in the domestic industry in the design and manufacturing of AC stepped-controlled reactors. In 2005, it successfully developed China’s first 500 kV AC stepped-controlled shunt reactor for the Xinzhou switching station in Shanxi Province. In 2010, it delivered the country’s first 750 kV, 100 Mvar AC stepped-controlled shunt reactor for the Anxi substation in Gansu Province. In 2013, it developed the first 750 kV, 130 Mvar AC stepped-controlled shunt reactor for the Shazhou substation in Gansu and the Yuka substation in Qinghai. Through participation in the development of multiple engineering projects, the manufacturer has accumulated extensive design and manufacturing experience, and all these products have demonstrated excellent operational performance in the field.

To scale new heights in global technology and gain a competitive edge in the market, the Chinese reactor manufacturer leveraged its successful experience in manufacturing 550 kV stepped-controlled shunt reactors to independently conduct focused R&D on key technologies and technical challenges. It developed numerous calculation programs for quantitative analysis, simulation, and optimized design of reactor products, ultimately succeeding in developing China’s first 750 kV, 140 Mvar reactor. This product features a rational structure, no local overheating, low losses, low noise, minimal vibration, low partial discharge, and reliable insulation performance.

Since AC stepped-controlled shunt reactors fundamentally differ in operating principle from conventional shunt reactors—and given the high voltage level and large single-unit capacity (140 Mvar at 750 kV)—technical challenges related to leakage magnetic field control, elimination of local overheating, and reduction of eddy current losses, stray losses, vibration, and noise have increased significantly. The manufacturer attached great importance to this project and, immediately upon receiving the order, formulated a dedicated quality and schedule assurance plan, designating the product as the focal point of an internal labor competition.

Building on the successful experience of previous projects, engineers collaborated to overcome key technical hurdles, conducting comprehensive simulation analyses and research to ensure product reliability. Before each production stage began, relevant workshops organized staff to thoroughly study manufacturing processes and technical documentation, proactively developing contingency plans for potential issues to control product quality at the source. Throughout production, the manufacturer rigorously enforced quality control and process discipline, arranged overtime and shift work to meet tight deadlines, and emphasized precision craftsmanship to guarantee quality. As a result, the product passed all tests successfully on the first attempt, reinforcing the manufacturer’s leadership and technological superiority in China’s reactor market and enhancing its overall market competitiveness.