JP2005151641A - Method of starting generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a generator starting method which enables the start of a generator even in case that input is small without using a windmill, an input detector, and a control switching means which are superfluous. <P>SOLUTION: A generator system, which is connected to a power system where this invention is applied, is equipped with a prime mover, a generator which is connected with the prime mover, using a connection means such a gear or the like, so as to convert rotational energy into electric energy, a power converter which converts power generated by the generator into DC, and a generator control means which outputs a voltage command to the power converter so as to control the generator. In the generator starting method which controls the torque of the generator by getting a torque command from the relation between the speed ω and the torque T, where the output becomes maximum to the input of the prime mover, and the speed ω of the generator, a torque compensation amount calculating means sets torque, negating the mechanical friction among the generator, the prime mover, and the above connection means, as torque compensation amount, and inputs a signal, where the torque compensation amount is added to the torque command, to a torque control means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for starting a power generating device with high power generation efficiency that can be started from a low input in a power generating device that converts energy such as wind power or hydraulic power into electric energy and is connected to an electric power system or has power storage means.

Generally, the generated torque with respect to the input of a prime mover such as a windmill exhibits characteristics as shown in FIG. 2 when the input is constant. That is, when the rotation is stopped, the torque is small with respect to the input, so that there is a problem that even if there is an input capable of generating power, the engine cannot be started until the starting torque becomes larger than the mechanical loss.
In response to this problem, wind power generation has been devised to attach a starter wind turbine that generates torque at a low input to the prime mover and lower the start input (for example, see Patent Document 1). In addition, when there is an input capable of generating power using an input amount detection means such as an anemometer, the generator is driven as a motor to accelerate, and when power generation is possible, the mode is switched to the power generation mode and power generation is started. (For example, refer to Patent Document 2). Further, there has been proposed a method in which when there is no input amount detection means, the generator is forcibly rotated by operating it as a motor at a certain interval while the generator is stopped, and power is generated if there is an input. Moreover, in a gas turbine power generation device, it is necessary to accelerate the turbine to a speed at which power can be generated. However, in order to accelerate the turbine, a separate power conversion device for acceleration is prepared. The method of driving by switching is taken (for example, see Patent Document 3).
JP-A-11-201020 (FIG. 1) JP-A-8-322298 (FIG. 1) JP 2002-89286 A (FIG. 1)

FIG. 7 shows a conventional control block diagram in wind power generation. In FIG. 7, 2 is a generator torque control means, 3 is a PWM voltage calculation means, 4 is a power converter, 5 is a generator current detection means, 6 is a generator, 7 is a generator speed detection means, and 8 is a current conversion. Means 9, addition means, 30 torque compensation calculation means, 32 maximum output speed calculation means, and 33 speed control means.
Next, the operation will be described. An input to the prime mover is detected by the input detection means 31, a speed command that gives the maximum efficiency with respect to the value inputted by the input detection means 31 is calculated by the speed command calculation means 32, The torque command is obtained by the controller 33 in comparison with the speed 6. The torque control means 2 calculates a voltage command so that the generator current detected by the current detection means 5 becomes the torque according to the torque command, and converts the voltage command into PWM by the voltage output means 3 to convert the voltage command into a power converter. 4 and the procedure of controlling the generator 6 was taken. There is also a method of calculating the torque command by predicting the input state from the power generated by the generator and the detected speed value without using the input detection means 31.
The input / output / speed relationship of the prime mover is as shown in FIG. 5, and when the generator is rotating, the size of the input can be estimated from the relationship between the speed and the output, so the maximum output speed can be calculated. . When the generator is not rotating, the output is always 0, so input detection means is required. A specific example of the input detection means 31 is an anemometer. This makes it possible to estimate the generator input when the generator is not rotating or in the low speed region where the generator speed is near zero.
In FIG. 5, the lower diagram shows the output of the prime mover with respect to the rotational speed ω of the generator at each input. The upper diagram shows the generator torque command for the generator rotational speed ω at each input. The maximum efficiency operation curve is a curve connecting the points where the output of the prime mover at each input becomes the maximum, and it is possible to operate the prime mover at the maximum efficiency by controlling the torque command to match the curve. . Therefore, if the maximum efficiency operation curve with respect to the generator rotational speed ω is calculated and stored in advance using the prime mover input as a parameter, the generator torque command for the generator rotational speed ω can be obtained.

However, the conventional generator starting method requires a wind turbine for starting, or the method of using the generator as an electric motor at the time of starting requires input detection means. The method of rotating as a motor at a constant interval has a problem that power generation efficiency is lowered because power is consumed by rotating the motor as a motor even when there is no input.
Further, in the gas turbine generator, control and switching of the power conversion circuit are required.
The present invention has been made in view of such various problems, and can generate a generator that can start a generator even when the input is small, without using an extra windmill, input detector, or control switching means. It aims at providing the starting method of a machine.

In order to solve the above problems, the present invention provides a prime mover that converts energy such as wind power and hydraulic power into rotational energy, and a generator that is connected using a connecting means such as the prime mover and a gear to convert rotational energy into electrical energy. A power converter that converts the electric power generated by the generator into direct current; generator control means that outputs a voltage command to the power converter and controls the generator; and a maximum output with respect to the input of the prime mover In the generator starting method for controlling the torque of the generator by obtaining a torque command from the relationship of the speed ω-torque T and the generator speed ω,
The torque compensation amount calculating means sets a torque that cancels mechanical friction of the generator, the prime mover, and the connecting means as a torque compensation amount,
A signal obtained by adding the torque compensation amount to the torque command is input to the torque control means.

Further, in the invention according to claim 1, the torque compensation amount calculation means sets a speed ω0 at which power generation is possible, and when the generator is stopped, the torque compensation amount is Tc0, and the speed of the generator So that it becomes 0 when ω is the set speed ω0,
When ω <ω0 Tc = Tc0− (Tc0 / ω0) × ω (1)
When ω ≧ ω0 Tc = 0 (2)
Thus, the torque compensation amount Tc is calculated.

Further, in the invention according to claim 2, the torque compensation amount calculation means sets the torque compensation amount to 0 until the generator stops when the generator rotates and exceeds a set speed. is there. Thus, the generator can be accelerated even with a minute input without providing an external input detector or switching means, and the power generation efficiency can be increased.
Further, in the invention according to claim 2 or 3, the torque compensation amount calculation means has an operation command input means, and sets a value for accelerating the generator even if the input to the prime mover is zero as the torque compensation amount. Then, when there is an input to the operation command input means, the speed is forcibly accelerated to a power generation rate.
According to a fourth aspect of the present invention, the generator is a gas turbine generator.

According to the method of the present invention, in a power generator that performs maximum efficiency control by a torque command, when a generator is stopped, a torque compensation setting that compensates for a mechanical loss is provided, so that a wind turbine for starting, etc. It is possible to start from a minute input without providing an additional prime mover or a detector for detecting the input amount. Further, since the generator is not operating during stoppage, the power consumption by the generator becomes zero. Therefore, the power generation operation efficiency can be increased.
Further, according to the method of claim 4, smooth acceleration and transition to power generation can be performed without providing an extra switching means in a power generation application that requires acceleration at start-up, such as gas turbine power generation. There is an effect.

  Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a generator control for implementing the method of the present invention. In FIG. 1, 1 is a maximum output torque command calculation means, 2 is a generator torque control means, 3 is a PWM voltage calculation means, 4 is a power converter, 5 is a generator current detection means, 6 is a generator, and 7 is a power generator. The machine speed detecting means, 8 is a current converting means, 9 is an adding means, and 30 is a torque compensation calculating means.
FIG. 1 of the present invention and FIG. 7 of the prior art show generator torque control means 2, PWM voltage calculation means 3, power converter 4, generator current detection means 5, generator 6, generator speed detection means 7, current This is common in that the conversion means 8 is provided. 1 of the present invention is different from FIG. 7 of the prior art in that a maximum output torque command calculation means 1 and a torque compensation calculation means 30 are provided.
Next, the input / output configuration of the generator control block diagram of FIG. 1 will be described. The maximum output torque command calculation means 1 inputs the generator speed ω output from the generator speed detection means 7, performs calculation described later, and outputs a torque command T to the addition means 9. The adding means 9 controls the torque signal T * (T * = T + Tc) obtained by adding the torque command T output from the maximum output torque command calculating means 1 and the torque compensation value Tc output from the torque compensation calculating means 30. Output to means 2. The torque control unit 2 inputs the torque signal T * and the current signal output from the current conversion unit 8 and outputs a voltage command to the PWM voltage calculation unit 3. The PWM voltage calculation means 3 performs PWM modulation on the voltage command based on the voltage command, and outputs it to a gate drive circuit (not shown) of the power converter 4. The power conversion device 4 controls the terminal voltage of the generator 6 based on the PWM modulation signal output from the PWM voltage calculation means 3.

Next, the operation of FIG. 1 will be described. The maximum output torque calculation means 1 calculates a torque command T that maximizes the power generated by the generator from the speed of the generator 6 detected by the generator speed detection means 7. A torque compensation value Tc is added to this to obtain a torque command T *. The current conversion means 8 converts the current detected by the current detection means 5 into a current used for control. The torque control unit 2 calculates a voltage command using the generator current converted by the current conversion unit and the torque command T *, PWM modulates the voltage command by the PWM modulation unit 3, and the power conversion unit 4 generates the generator. 6 terminal voltage is controlled. The maximum output torque calculation means 1 always obtains a torque command from the detected speed according to the maximum efficiency operation curve connecting the maximum output points at each input from the relationship of the speed ω-torque T shown in FIG. Can be operated with maximum efficiency.
FIG. 6 is a block diagram of another embodiment of the present invention. FIG. 6 is provided with torque compensation calculation means 30 for changing the torque compensation value according to the speed detection value. The torque compensation computing means 30 computes from the torque compensation completion speed ω0 and the torque compensation initial value Tc0 as follows.

When ω <ω0 Tc = Tc0− (Tc0 / ω0) × ω (1)
When ω ≧ ω0 Tc = 0 (2)
By setting ω0 to the maximum efficiency speed when the minimum input capable of generating power is entered, it is possible to smoothly accelerate to the maximum efficiency speed with a few inputs.
Further, once the speed of the generator 6 exceeds the torque compensation completion speed ω0, the torque compensation value is set to zero. As a result, even when there is no input, it is possible to recover even regenerative energy due to the deceleration of the generator or prime mover, resulting in improved efficiency.
In the case of a gas turbine generator, it is necessary to once accelerate the generator to a power generation possible speed at the start of power generation. For such applications, the torque compensation calculation means can be used to automatically switch between acceleration and power generation. That is, by setting the torque necessary for acceleration to the torque compensation initial value Tc0 and setting the torque compensation completion speed at a speed that exceeds the speed at which power generation is possible, acceleration is smoothly performed. Since it becomes 0, it shifts to a normal power generation state. However, in order to prevent the torque compensation initial value Tc0 from inadvertently accelerating the generator, an operation start / stop input function is introduced so that an operation start command is input when the generator is started.
3 and 4 show the configuration of a power generator to which the present invention is applied. FIG. 3 is connected to a power system, and FIG. 4 is a power generation apparatus having power storage means.
FIG. 3 shows a configuration example of the power generator connected to the system. The prime mover 11 is connected to the generator 13 via a connecting means 12 such as a gear, and the power conversion device 14 converts the electric power generated by the generator into a direct current amount. The generator control means 17 detects the speed of the generator 13 by the speed detection means 16 and detects the current flowing through the generator 13 by the generator current detection means 15 so that the torque to the generator 13 becomes a desired value. A voltage command is given to the power converter 14. The output control means 19 detects the voltage of the power system by the output voltage detection means 24, outputs a voltage command that makes the output voltage an appropriate voltage waveform, and outputs it by the output power converter 18. The output of the output power converter 18 is connected to the power system 22 by the system connection means 21 after removing harmonics by the output filter 20. Further, the system connection means 21 supplies power to the load device 23 using the power from the power system 22 and the power generated by the generator.
FIG. 4 shows an example of the configuration of a stand-alone power generator having power storage means. The output unit of the power converter 14 is connected to the power storage unit 26 via the power storage control unit 25. Further, the output power conversion device 18 is connected in parallel with the power storage control means 25, converted into an appropriate voltage waveform by the output voltage control means 191, and supplied to the load device 231. The power storage control means 25 discharges the power storage means 26 while the generator 13 is not generating power and supplies power to the load 231 via the power output device 18, and the generated power is consumed by the load device 231 during power generation. Control is performed so that the surplus power is stored in the power storage means 26 when the power is larger.

Control block diagram showing an embodiment of the present invention The figure which shows the speed-torque-output characteristic of the motor | power_engine to which this invention is applied. The figure which shows the electric power generating apparatus connected to the electric power grid which applies this invention The figure which shows the electric power generating apparatus which has an electrical storage means to which this invention is applied. Diagram showing examples of prime mover speed-output and speed-torque characteristics Control block diagram showing an embodiment of claim 2 of the present invention Conventional power generation control block diagram

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Maximum output torque command calculating means 2 Generator torque control means 3 PWM voltage calculating means 4, 14 Power converter 5 Generator current detecting means 6, 13 Generator 7 Generator speed detecting means 8 Current converting means 9 Adding means 11 Motor 12 connection means 15 generator current detection means 16 generator speed detection means 17 generator control means 18 output power conversion means 19 output control means 191 output voltage control means 20 output filter 21 system connection means 22 power system (power supply)
23, 231 Load device 24 Output voltage detection means 25 Storage control means 26 Storage means 30 Torque compensation calculation means 31 Input detection means 32 Maximum output speed calculation means 33 Speed control means

Claims (5)

A prime mover that converts energy such as wind power or hydraulic power into rotational energy, a generator that is connected using a connection means such as a prime mover and gears, and that converts rotational energy into electrical energy, and converts the electric power generated by the generator into direct current The power converter, the generator control means for controlling the generator by outputting a voltage command to the power converter, the relationship between the speed ω-torque T at which the output is maximum with respect to the input of the prime mover and the power generation In the generator starting method for controlling the torque of the generator by obtaining a torque command from the machine speed ω,
The torque compensation amount calculating means sets a torque that cancels mechanical friction of the generator, the prime mover, and the connecting means as a torque compensation amount,
A generator starting method, wherein a signal obtained by adding the torque compensation amount to the torque command is input to a torque control means. The torque compensation amount calculation means sets a speed ω0 at which power generation is possible. When the generator is stopped, the torque compensation amount is Tc0, and when the generator speed ω is the set speed ω0, the torque compensation amount calculation means 0 So that
When ω <ω0 Tc = Tc0− (Tc0 / ω0) × ω (1)
When ω ≧ ω0 Tc = 0 (2)
The generator starting method according to claim 1, wherein the torque compensation amount Tc is calculated by:   The generator according to claim 2, wherein the torque compensation amount calculation means sets the torque compensation amount to 0 until the generator stops when the generator rotates and exceeds a set speed. Starting method.   The torque compensation amount calculation means has an operation command input means, and sets a value for accelerating the generator even if the input to the prime mover is 0 as the torque compensation amount, and there is an input to the operation command input means. 4. The method of starting a generator according to claim 2 or 3, wherein the generator is forcibly accelerated to a speed capable of generating power.   The generator starting method according to claim 4, wherein the generator is a gas turbine generator.

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