CN203942288U - A kind of double-fed wind generator AC and DC grid-connected system - Google Patents

Abstract

The utility model discloses an AC and DC grid-connected system of a doubly-fed generator set, which comprises a measurement control module, a prime mover and its transmission and speed-up module, a doubly-fed asynchronous generator, a converter on the generator side, a rectifier on the grid side, Energy conversion module, AC power grid; Since the active power output by the stator of the doubly-fed generator set is basically constant during super-synchronous operation, the stator side of the doubly-fed wind turbine can output a basically constant active power in a relatively wide speed range. The utility model can reduce the impact of the output power of the doubly-fed asynchronous generator set on the power grid when the speed fluctuates, and can even make the doubly-fed asynchronous generator set serve as the basic power supply of the power grid to improve the stability of the power grid operation; while the output power of the rotor is converted into other stored or consumed. The technical means of the system is simple, easy to implement, low in cost, easy to implement, has outstanding technical effects, and can be widely used in wind power, water power or thermal power plants and the like.

Description

A doubly-fed generating set AC and DC grid-connected system

technical field

The utility model relates to the technical field of wind power, hydraulic power or thermal power generation, in particular to an AC and DC grid-connected system of a doubly-fed generating set.

Background technique

The power output from the doubly-fed asynchronous generator to the grid consists of two parts, that is, the power output directly from the stator and the power output from the rotor through the frequency converter.

For example, the mechanical speed of a wind turbine is allowed to vary with the wind speed. Through the control of the generator, the wind turbine runs at the best blade tip speed ratio, so that the whole operating speed range has the best power coefficient. When the speed of the generator is lower than the speed of the air-gap rotating magnetic field, the generator is running at a subsynchronous speed. In order to ensure that the frequency emitted by the generator is consistent with the frequency of the grid, the frequency converter is required to provide positive phase sequence excitation to the rotor of the generator, to give the rotor The winding inputs an excitation current whose direction of the rotating magnetic field is the same as the mechanical direction of the rotor. At this time, the braking torque of the rotor is opposite to the mechanical rotation of the rotor, and the current of the rotor must be in the opposite direction to the induced counter electromotive force of the rotor, and the slip rate decreases. , the stator feeds electric power to the power grid, and the frequency converter inputs power to the rotor winding; when the speed of the generator is higher than the speed of the air-gap rotating magnetic field, the generator runs at a supersynchronous speed, in order to ensure that the frequency emitted by the generator is consistent with the frequency of the power grid , it is necessary to input an excitation current whose rotating magnetic field direction is opposite to the mechanical direction of the rotor to the rotor winding. At this time, the frequency converter provides negative phase sequence excitation to the generator rotor to increase the slip, and the frequency converter absorbs power from the rotor winding; when When the rotation speed of the generator is equal to the rotation speed of the air gap rotating magnetic field, the generator is running at synchronous speed, and the frequency converter should provide DC excitation to the rotor. The generated torque is in the same direction, and both the stator and the rotor feed electric power to the grid. The curtailment of wind power generation is due to the suspension of wind turbines in some wind farms caused by the local grid’s insufficient capacity and the instability of wind power. Unstable wind power output requires other power sources to provide free peak-shaving services, and pumped storage, gas-fired power generation and other peak-shaving and frequency-regulating power sources need to be built. When peak-shaving capacity is in short supply, wind curtailment is particularly serious. Optimizing planning Power supply structure and power grid layout, to expand the wind power consumption market, also need to promote the coordination of wind power production and consumption through technological innovation.

Similar to wind power generation, the water turbine in hydropower generation can also realize variable speed operation through the double-fed asynchronous generator according to the working head, flow and other parameters under the working conditions to improve the operation efficiency of the water turbine and improve the operating conditions.

Contents of the invention

The purpose of the utility model is to reduce the impact of the output power of the doubly-fed asynchronous generator set on the power grid when the wind speed fluctuates or the working head and flow of the water turbine change, and to provide a doubly-fed generator set AC and DC grid-connected system; the output of the stator winding is more stable The power is directly integrated into the AC grid, which can make the double-fed asynchronous generator set the basic power supply of the grid and improve the stability of the grid operation; while the power output by the rotor is converted into other forms of energy storage or consumption.

The utility model is realized through the following technical solutions:

An AC and DC grid-connected system for doubly-fed generator sets, including a measurement control module, a prime mover and its transmission and speed-up module, a doubly-fed asynchronous generator, a generator-side converter, a DC bus, an energy conversion module, and a grid-side Rectifier, AC busbar, step-up transformer, AC grid;

The measurement control module is sequentially connected to the prime mover and its transmission and speed-up module, double-fed asynchronous generator, AC bus, step-up transformer, and AC power grid;

The generator-side converter is sequentially connected to the DC bus and the grid-side rectifier;

The energy conversion module is also connected to the DC bus;

The generator-side converter is also connected to the doubly-fed asynchronous generator, and the grid-side rectifier is also connected to the AC bus.

The generator-side converter is connected to the rotor excitation winding of the doubly-fed asynchronous generator; the AC bus is connected to the stator winding of the doubly-fed asynchronous generator.

The prime mover includes a wind generator, a hydro generator or a thermal generator.

The operation method of the AC and DC grid-connected system of the above-mentioned doubly-fed generator set is as follows,

One: The measurement control module measures the speed of the doubly-fed asynchronous generator, and determines the operating status of the doubly-fed asynchronous generator according to the speed of the doubly-fed asynchronous generator;

Two: The measurement control module is used to control the frequency, amplitude and phase parameters of the generator-side converter to realize the active and reactive decoupling control of the doubly-fed asynchronous generator;

Three: The prime mover and its transmission and speed-up module convert kinetic energy and potential energy into mechanical energy, and increase the speed of the doubly-fed asynchronous generator through the transmission and speed-up module, or directly drive the doubly-fed asynchronous generator without speed-up;

Four: The doubly-fed asynchronous generator converts mechanical energy into electrical energy, and the AC power output by the stator coil of the doubly-fed asynchronous generator is directly sent to the AC grid;

Five: When the doubly-fed asynchronous generator is running in a super-synchronous state, the AC output from the rotor winding of the doubly-fed asynchronous generator is rectified into DC by the generator side converter and output to the DC bus, which is supplied to the energy conversion module to convert the electric energy be thermal energy or hydrogen energy;

Six: When the double-fed asynchronous generator is running in a synchronous state, the grid-side rectifier rectifies the AC power of the grid into a DC output to the DC bus, and the generator-side converter outputs the DC voltage of the DC bus to the rotor excitation of the double-fed asynchronous generator winding;

Seven: When the doubly-fed asynchronous generator is running in a sub-synchronous state, the grid-side rectifier rectifies the AC power of the grid into a DC output to the DC bus, and the generator-side converter converts the DC voltage of the DC bus into a low-frequency AC output to the doubly-fed asynchronous generator rotor field winding;

Eight: The grid-side rectifier converts the AC input from the AC grid into DC output DC bus, provides excitation for double-fed asynchronous generators in synchronous and sub-synchronous states, and stabilizes the DC bus voltage;

Nine: The DC bus provides energy flow channels for the generator-side converter, grid-side rectifier and energy conversion module;

Ten: The energy conversion module converts the electric energy output by the generator-side converter and grid-side rectifier into heat energy, hydrogen energy storage or consumption.

Application of AC and DC grid-connected systems of doubly-fed generator sets:

When applied to a brushless double-fed generator, the stator coil of the double-fed asynchronous generator corresponds to the power winding of the brushless double-fed generator, and the rotor coil of the double-fed asynchronous generator corresponds to the control winding of the brushless double-fed generator ;or,

When multiple doubly-fed asynchronous generators are used in parallel operation in wind, hydraulic or thermal power plants, each doubly-fed asynchronous generator is equipped with a generator-side converter, measurement control module, prime mover and its transmission It can be shared with the speed-up module, the stator winding of the doubly-fed generator connected to the common AC bus, the generator-side converter connected to the common DC bus, the grid-side rectifier, the energy conversion module and the step-up transformer.

Compared with the prior art, the utility model has the following advantages and effects:

According to the operating state of the double-fed asynchronous generator, the utility model incorporates the relatively stable active power output by the stator coil of the engine into the AC power grid, and sends the output power of the rotor coil with large fluctuations in generator power to the water electrolyzer or heat supply, etc. The energy conversion module converts it into other forms of energy for storage or consumption. For example, when used in wind farms, it can reduce the impact of wind turbine stator output power on the grid when wind speed fluctuates, and can even make double-fed wind turbines as The basic power supply of the grid can improve the stability of the grid operation; when applied to hydropower generation, it can improve the energy conversion efficiency of the turbine and improve the operating conditions of the turbine

The technical means of the utility model is simple and easy to implement, low in cost, easy to realize, and has outstanding technical effects.

The utility model can be widely used in wind power, water power or thermal power plants.

Description of drawings

Fig. 1 is the structural representation of the utility model.

Detailed ways

Below in conjunction with specific embodiment the utility model is described in further detail.

Example

As shown in Figure 1. The AC and DC grid-connected system of the double-fed generating set of the utility model includes a measurement control module, a prime mover and its transmission and speed-up module, a double-fed asynchronous generator, a generator-side converter, a DC bus, an energy conversion module, and a power grid Side rectifier, AC busbar, step-up transformer, AC power grid;

The measurement control module is sequentially connected to the prime mover and its transmission and speed-up module, the doubly-fed asynchronous generator, and the AC bus;

The generator-side converter is sequentially connected to the DC bus and the grid-side rectifier;

The energy conversion module is also connected to the DC bus;

The generator-side converter is also connected to a doubly-fed asynchronous generator, and the grid-side rectifier is also connected to an AC bus and a DC bus.

The generator-side converter is connected to the rotor excitation winding of the doubly-fed asynchronous generator; the AC bus is connected to the stator winding of the doubly-fed asynchronous generator.

The prime mover includes a wind generator, a hydro generator or a thermal generator.

The operation method of the AC and DC grid-connected system of the above-mentioned doubly-fed generator set is as follows,

One: The measurement control module measures the speed of the doubly-fed asynchronous generator, and determines the operating state of the doubly-fed asynchronous generator according to the speed of the doubly-fed asynchronous generator; During the following operations, make the wind rotor of the wind generator work in the maximum wind energy tracking state, and output the maximum power when the doubly-fed asynchronous generator runs above the rated speed;

Two: The measurement control module is used to control the frequency, amplitude and phase parameters of the generator-side converter to realize the active and reactive power decoupling control of the doubly-fed asynchronous generator;

Three: The prime mover and its transmission and speed-up module convert kinetic energy and potential energy into mechanical energy, and increase the speed of the doubly-fed asynchronous generator through the transmission and speed-up module, or directly drive the doubly-fed asynchronous generator without speed-up;

Four: The doubly-fed asynchronous generator converts mechanical energy into electrical energy, and the AC power output by the stator coil of the doubly-fed asynchronous generator is directly sent to the AC grid;

Five: When the doubly-fed asynchronous generator is running in a super-synchronous state, the AC output from the rotor winding of the doubly-fed asynchronous generator is rectified into DC by the generator side converter and output to the DC bus, which is supplied to the energy conversion module to convert the electric energy other forms of energy such as heat or hydrogen;

Six: When the double-fed asynchronous generator is running in a synchronous state, the grid-side rectifier rectifies the AC power of the grid into a DC output to the DC bus, and the generator-side converter outputs the DC power of the DC bus to the rotor excitation winding of the double-fed asynchronous generator ;

Seven: When the doubly-fed asynchronous generator is running in a sub-synchronous state, the grid-side rectifier rectifies the AC power of the grid to a DC output to the DC bus, and the generator-side converter converts the DC power of the DC bus into a low-frequency AC output to the doubly-fed asynchronous power generation The rotor field winding of the machine;

Eight: The grid-side rectifier converts the AC input from the AC grid into DC output to the DC bus, provides excitation for the rotor coil of the double-fed asynchronous generator in synchronous and sub-synchronous states, and stabilizes the DC bus voltage. It can also be used when the grid load is low Absorb power from the grid and output it to the energy conversion module to fill the valley load of the grid;

Nine: The DC bus provides energy flow channels for the generator-side converter, grid-side rectifier and energy conversion module;

Ten: The energy conversion module converts the electric energy output by the generator-side converter and the grid-side rectifier into heat energy, hydrogen energy and other forms of energy storage or consumption through resistors and water electrolyzers.

The application of AC and DC grid-connected systems of doubly-fed generator sets is as follows:

When applied to a brushless double-fed generator, the stator coil of the double-fed asynchronous generator corresponds to the power winding of the brushless double-fed generator, and the rotor coil of the double-fed asynchronous generator corresponds to the control winding of the brushless double-fed generator ;or,

When multiple doubly-fed asynchronous generators are used in parallel operation in wind, hydraulic or thermal power plants, each doubly-fed asynchronous generator is equipped with a generator-side converter, measurement control module, prime mover and its transmission It can be shared with the speed-up module, the stator winding of the doubly-fed generator connected to the common AC bus, the generator-side converter connected to the common DC bus, the grid-side rectifier, the energy conversion module and the step-up transformer.

As mentioned above, the utility model can be better realized.

The implementation of the present utility model is not limited by the above-mentioned examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present utility model should be equivalent replacement methods. Included within the protection scope of the present utility model.

Claims (3)

1. A doubly-fed generating set AC and DC grid-connected system, characterized in that: Including measurement control module, prime mover and its transmission and speed-up module, doubly-fed asynchronous generator, generator-side converter, DC bus, energy conversion module, grid-side rectifier, AC bus, step-up transformer, AC power grid; The measurement control module is sequentially connected to the prime mover and its transmission and speed-up module, the doubly-fed asynchronous generator, and the AC bus; The generator-side converter is sequentially connected to the DC bus and the grid-side rectifier; The energy conversion module is also connected to the DC bus; The generator-side converter is also connected to a doubly-fed asynchronous generator, and the grid-side rectifier is also connected to an AC bus and a DC bus. 2. The AC and DC grid-connected system of doubly-fed generator set according to claim 1, characterized in that: the generator-side converter is connected to the rotor excitation winding of the doubly-fed asynchronous generator; the AC bus is connected to the doubly-fed asynchronous generator The stator winding of the machine. 3. The doubly-fed generating set AC and DC grid-connected system according to claim 1, characterized in that: the prime mover includes a wind generator, a hydro generator or a thermal generator.