Recently, at the Southwestern Institute of Physics of the China National Nuclear Corporation (CNNC) in Chengdu, my country's first 300,000 kVA vertical pulse generator system passed acceptance testing, with overall parameters reaching international advanced levels. "As a six-phase high-current pulse generator, its discharge power within approximately 10 seconds during operation is equivalent to the 300,000 kW capacity of the Qinshan Phase I Nuclear Power Plant," said Li Qiang, deputy director of the Fusion Science Institute at the Southwestern Institute of Physics of CNNC.
The unit, jointly developed by the Southwestern Institute of Physics of China National Nuclear Corporation and Harbin Electric Machinery Co., Ltd. of Harbin Electric Corporation, weighs about 800 tons and is about 15.5 meters high . It is a large pulsed "energy driver" developed to meet the high power and high energy storage power supply requirements of the China Fusion Engineering Test Reactor (HL-2M), an advanced fusion research device in China.
During operation, the generator, driven by the electric motor, can reach a speed of 498 revolutions per minute (rpm) after 15 minutes. Then, through rotor excitation, the speed is reduced to 335 rpm within 15 seconds, releasing 1350 megajoules of energy. After releasing energy, the generator speed will increase again to 498 rpm, maintain this speed for 5 minutes, and then decrease again to discharge, completing one work cycle. "The unit has a rated speed of 500 rpm, a total energy storage of 2600 megajoules, a rated voltage of 3 kV, and a rated current of 29 kA. It is currently the largest vertical six-phase pulse generator set in China," said Li Qiang. He added that compared to the three pulse generator sets used in the original "China Toroidal Reactor 2 (HL-2A)," "the energy release capacity and power output of this new unit alone are equivalent to the sum of the previous three."
Pulse generator sets come in two types: vertical and horizontal. Traditional horizontal units are limited by the weight of the rotor and flywheel, making them unsuitable for large-capacity pulse generator sets; vertical units, with their upright shafts, do not have this problem. "As the first vertical-shaft pulse generator in China, this unit differs greatly from conventional hydro generators in both its motor structure and load type. Previously, there were no mature calculation methods or design experience, requiring significant innovation," said Xuan Weimin, deputy chief engineer of the Institute of Fusion Science at the Xi'an Institute of Physics and Engineering. Inside the massive pulse generator, the rotor speed constantly changes, presenting unprecedented challenges in maintaining overall equipment stability, controlling vibration amplitude, designing the cooling system, and programming the six-phase motor. Ultimately, the research team pioneered several unique technologies, overcoming technical difficulties such as six-phase high-current generators, high-inertia high-speed rotors, and wide-frequency variable control and protection systems, resulting in a number of innovative achievements with independent intellectual property rights during the development process.
The China Tokamak 2M (HL-2M) is another large-scale tokamak device newly developed based on China's first large-scale tokamak device with a divertor configuration, the China Tokamak 2A (HL-2A). Its research goal is to explore controlled nuclear fusion and realize humanity's ultimate energy pursuit of an "artificial sun." The successful development of this pulse generator will drive the plasma current of the HL-2M device to more than twice that of previous existing devices, and the plasma temperature to exceed 150 million degrees Celsius, thus providing strong support for conducting plasma physics experiments and key technology research at core-level parameters on this device.
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