In order to better meet the market demand for variable-speed constant-frequency generators, reduce the cost of new energy generation, and improve the level of safe operation of the power grid, Qingdao Meihua Permanent Magnet Electric Technology Co., Ltd. and Wang Guangshun, the distinguished professor of Shandong University, jointly developed the world’s first Variable speed constant frequency generator that can be directly connected to the grid. It can meet the requirements for reactive power adjustment during grid-tied operation; it can meet the technical requirements for low voltage ride through. The ability to meet grid-connected power quality standards requires that the generator not only eliminates inverters, but also does not require pre-governor system. This technology can significantly reduce the investment cost of variable-speed constant-frequency generators. At the same time, the generator also has intelligent features such as instantaneous control of active power and flexible grid connection, which can be widely used in variable-speed power generation systems such as wind power, water conservancy, tide, solar energy, and ships.

Wind power generation is the most typical variable-speed power generation equipment, and its technical requirements are very high, involving cutting-edge technologies in various disciplines. The direct grid-connected variable-speed constant-frequency generator is used in wind power generation and can fully exert its technical and economic advantages.

1. Realizing wide-ranging adjustment of reactive power The general variable-speed constant-frequency wind generator cannot directly meet the requirements of the grid for reactive power adjustment. Even if a full-power inverter wind generator is used, the low-voltage ride-through capability of the wind turbine in case of grid faults The reactive power output capability cannot be compared with the main power generating unit of the power grid. After large-scale wind farms were built, the magnitude of reactive power adjustment became a major constraint for grid connection. The newly developed straight VSCF generator reactive power adjustment and low voltage ride through performance indicators are much higher than the current wind power grid connection technology standards, and close to the grid main synchronous generator level.

2. Low-harmonic output The direct-parallel variable-speed constant-frequency generator adopts a combined harmonic suppression design, so that the harmonic content of the output voltage and current is controlled within the scope of the [standard]. The low harmonic output is the basic requirement for the generator to be connected to the grid. Especially when large-scale wind power is connected to the grid, the problem of unsolvable harmonics will limit the scale development of wind power. Direct and variable speed constant frequency generators have shown greater advantages in current harmonic control.

3, active power output curve smooth adjustable and variable speed constant frequency generator set using fuzzy control technology and inertial energy storage technology, can instantly complete active power control, and maintain the generator active power output curve smooth and adjustable. At the same time, it can also prevent the gens overload caused by turbulence and protect the safe operation of the blades, tower and transmission system. The generator can also run in phase to help the power grid to solve the problem of over-voltage, so as to greatly improve the long-distance transmission capacity of new energy power.

4. Saving Investment Costs Since the direct-variable variable-speed constant-frequency generator set subtracts power electronic devices, the total cost of the entire set of generators is significantly lower than that of other types of variable-speed constant-frequency generators, which is conducive to the industrialization and large-scale development of wind power. Moreover, since the new technology route is adopted for the direct-variable variable-speed constant-frequency generator set, safety and economy are improved, and the cost per unit power generation cost during the life cycle is greatly reduced. With the increase of the power of direct-connected VSCF wind turbines, its superiority will be more prominent. The unit can better meet the needs of large offshore wind farm construction.

5、Safety and reliability improvement The direct-variable variable-speed constant-frequency generator adopts medium-speed design in wind power generation. There is no speed-regulating device in the power transmission process. The speed-increasing box is directly connected with the generator, and the generator directly combines the output power into the power grid. Therefore, the impact of high-frequency pulse current of the inverter on the coil is avoided, so the reliability is improved greatly compared to the generator of the variable current mode, and the downtime of the entire life cycle can be reduced by more than 20%.

6. Increased power generation efficiency The straight variable-speed constant-frequency generator set can have a wider speed range, lower the minimum operating speed, and allow the generator to be overloaded for a certain period of time, thus effectively widening the speed-changing wind belt and making the power generation. The number of equivalent hours of all-weather utilization of the aircraft has increased significantly.

The direct-variable VSCF generators have a wide range of application prospects in the field of new energy and variable-speed drives. With the continuous improvement of this technology, it will be possible to work with other types of generators in the near future to provide efficient clean energy to humans. Task. This scientific and technological achievement is also an important technological contribution of China to the world's new industrial revolution. It can promote the scale development of new energy and related industries, and will end the reliance on the status quo in foreign countries for the core technologies of China's new energy industry. This technology has obtained national invention patents. The direct grid-connected variable-speed constant-frequency generator adopts a new motor principle, which is a leap in motor manufacturing technology and will surely play an active role in promoting industrial upgrading in China.