JPS61247298A - Operation controlling method for variable speed generator system - Google Patents

Abstract

PURPOSE:To increase the system efficiency in a generation and a pumping operation by controlling the phase angle of the secondary circuit by the difference between a target rotating speed and a real rotating speed and the difference between the target power and the actual power. CONSTITUTION:When a static head H and an output command P0 are given, a command value calculator 15 calculates the opening command value for a governor valve and a speed command value N0 considered for the efficiency. A water wheel characteristic unit 13 decides the characteristics of a water wheel 12 on the basis of a static head H, a governor valve opening and a rotating speed N detected by a tachometer generator 11. A phase angle calculator 16 calculates a phase angle on the basis of the effective power, the output command P0, a speed command value N0 and a rotating speed N. The exciting amount of the secondary circuit is set by an exciting amount setter 17 on the basis of the phase angle, the rotating speed N and further the output of a voltage regulator 18 for controlling the voltage value of the exciting amount.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to an operation control method for a variable speed power generation system that operates an induction generator with secondary excitation at a desired rotation speed, and particularly relates to a method for controlling the operation of a variable speed power generation system that operates an induction generator with secondary excitation at a desired rotation speed, and particularly for power generation and pumping 0AFC operation. This relates to a method for operating a variable speed power generation system to stably control the target value.

[Background of the invention]

In conventional pumped storage power generation systems, it is not possible to adjust the load when pumping water, and the efficiency of the system changes due to changes in the power required by the system during power generation and pumping operation, and the pumping height during pumping. There is a problem with this. For this reason, research is currently underway to operate the system with high efficiency, regardless of power generation or head. One of these studies is to develop a synchronous machine, which is a conventional pumped storage generator.
A so-called variable speed power generation system that operates with an induction machine with sub-excitation is being considered. If it is a variable speed power generation system,
Research is being conducted to realize this from the perspective that highly efficient system operation is possible regardless of power generation or head. However, the current situation is that no specific control method has been studied so far.

[Purpose of the invention]

Therefore, an object of the present invention is to provide a method for controlling the operation of a variable speed power generation system, which increases system efficiency during power generation and water pumping operations, and also enables stable control to a target value during AFC operation.

[Summary of the invention]

For this purpose, the present invention is designed to control the difference between the target rotational speed and the actual rotational speed, the difference between the target power and the actual power, and the phase angle of the secondary circuit.

This is because the operating conditions for obtaining a desired power generation power are determined by the relationship between the effective head per rotation speed and the governor vent opening, but the efficiency of a variable speed power generation system is determined by the rotation speed, so the target rotation speed is first set. The opening degree of the vent will be controlled to match the desired power generation power. However, since the rotation speed is determined by the difference between the water turbine input and the generator output, it is necessary to change the generator output and move the internal phase angle in order to match the rotation speed and generated power to the command value. #: This is a variable speed power generation system using an induction machine with secondary excitation to move the phase angle of the 12th order circuit. Specifically, the above difference is used to manipulate the phase angle.

[Embodiments of the invention]

The present invention will be explained below with reference to FIGS. 1 to 6.

First, before entering into a detailed explanation of the present invention, an overview of the system and control of the variable speed pumped storage power generation system will be explained.

Figure 81 shows the outline of the system.

According to this, stator l has a% C phase winding 51~5C.
However, the rotor 2 is also provided with a%C phase windings 6a to 6C. Here, the rated frequency is fl
If the speed of the rotor 2 is set to 8, the speed of the rotor 2 is f(1-s), and by exciting the excitation winding of the rotor 2 at a frequency of the frequency of the rotor 2, the magnetic field of the rotor 20 becomes zero. (Synchronous speed l
L), which is the same speed as the rotating magnetic field of the stator 1. The rotation speed of the rotor 2 is detected by the rotation speed measuring section 7. Based on the detected rotation speed, the speed detection section 3 detects the speed frequency, and then the voltage generation section 4 detects the speed based on the speed frequency. If you generate a voltage that excites the secondary winding, it will work at any rotation speed.

Even if rotation is performed, a voltage at the system frequency can always be generated in the armature winding. That is, the rotating magnetic field of the rotor 2 becomes the sum of the rotational speed of the rotor 2 itself and the frequency.

f(1-s)+fs-f...
...ω If the secondary winding is excited at the maximum frequency in this way, an output at the rated frequency can be obtained from the stator winding.

Next, the outline of the control will be explained with reference to FIG. 2. When the static head H and the output command P- are given, the command value calculation circuit 1
5, the opening degree command value and speed command value N of the governor valve are calculated in consideration of efficiency. The valve opening degree of the governor valve is determined by outputting the opening degree command value with a slight time delay compared to the governor valve 14. The water turbine characteristics section 13 determines the characteristics (torque characteristics) of the water turbine 12 based on the static head H1 and the governor valve opening, as well as the number of revolutions N detected by the speed generator 11. The rotor 2 of the induction generator is rotated. The induction generator is operated while connected to the power system 10, and the active power calculation unit 21 calculates the active power based on the outputs of the current transformer 19 and voltage transformer 20, and calculates the phase angle of the secondary winding. It is configured to be given to the calculation unit 16. The phase angle calculation section 16 calculates the phase angle based on the output command P0, speed command value N0, and rotational speed N in addition to the active power. The excitation amount of the secondary circuit is set by the excitation amount setting section 17 based on this phase angle and the rotation speed N, and also the output of the voltage adjustment section 18 that controls the voltage value of the excitation amount, and the set excitation amount is The phase shifter 23 corresponding to the arc phase is phase-shifted by ZaC, and the excitation windings 221-2
It is designed to be given to 2C.

In this way, the opening command value and speed command value of the governor are determined for the output command, and it is necessary to calculate the phase angle of the secondary winding based on these values to perform control, but it is necessary to perform control stably. The reality is that the method has not yet been established.

The present invention aims to perform phase angle control optimally, and this will be specifically explained below.

FIG. 3 shows a state in which a so-called variable speed power generation system, which can be operated at any rotational speed using a steam generator with secondary excitation, is connected to the grid via a power transmission line. As shown in the figure, the variable speed power generation system G is connected to the grid 8 via a power transmission line, and the power transmission isL is provided with a voltage transformer FT and a current transformer CT to calculate active power.

Francis turbines are generally used for pumped storage power generators, and the relationship between turbine output and efficiency is shown in Figure 4. Fig. 4 shows the water turbine output on the horizontal axis, efficiency on the vertical axis, and rotation speed as parameters.

Ps, PeFi water turbine output, +71. Da■ stands for efficiency, N
s and Ns indicate the rotational speed, and show that the maximum efficiency at the output PR is the rotational speed N1, and the maximum efficiency at the output Pa is the rotational speed Ng. Although the rotational speed at which efficiency is maximized varies depending on the output, the purpose of the present invention is to operate at maximum efficiency.

In Fig. 3, the variable speed power generation system G can operate with high efficiency when a command for the power generation required for the generator is given from the operating end T, taking into consideration the characteristics of the generator and the water head. The rotational speed of the generator and the opening degree of the governor valve V of the water turbine are determined by the control #command unit C, and the operation must be controlled to match these values. When a command to reduce the generator output is given in such a state, the rotation speed and governor valve opening are adjusted based on the generator output and water head to maximize the efficiency of the generator, using a method given in advance. The rotational speed and valve opening degree are controlled to achieve these target values for efficient operation.

On the other hand, the deviation of the generator rotation speed from the rated value is caused by the excitation circuit E8
By using the vesi frequency as the information, an output at the rated frequency can be obtained as described above.

Next, explaining secondary excitation, the excitation voltage for the three-phase secondary excitation winding shown in FIG. 2 is expressed as follows.

However, Vga to Vfs are the excitation voltages of phases a to C, respectively, E is the voltage value determined by the operating state of the variable speed machine, and δ is the phase angle determined by the operating state of the variable speed machine. Δδ is a phase angle controlled by the output of the control command unit C.

The control command section C calculates the phase difference angle Δat-69 among the rounding functions to obtain the CaO excitation amount to the lever a according to the command given from the operating end T, and Δa for the active power control command, and , reactive power can be controlled by E.

The purpose of the present invention is to stably control the active power to the target value during human FC operation in the above equation, but for this rounding, the phase angle (Δδ) of the excitation circuit is controlled to adjust the rotation speed and power to the target value. It is necessary to match the For this reason, effective power and rotational speed can be considered as information for moving the phase angle. That is, the phase angle Δδ is expressed as follows.

Δδ−ks(N−N,) ・・・・・・・・・
・(3) Δδ−, (P−P,) ・・・・
...(4) However, N, P, t: t indicates the target values of rotation speed and active power, respectively, N and P indicate the actual rotation speed and active power, respectively, and kl v kl indicates a constant. .

FIG. 5 shows a specific control method in this case.

The one shown in Figure 86 can be considered. That is, in power generation operation, when the active power is used for control, the target active power is reached more quickly than when the rotation speed is used for control.

Therefore, as shown in Fig. 5, the rotational speed N is the target! liN.

If CP has not been reached, first calculate the difference in active power CP.

-P, ), and after matching the active power P and t-target P, control is performed using the difference in rotational speed (N-N, ).

Until the absolute value of P is reached, the difference in rotational speed (N-N,
), and when the target value is reached, the difference in active power (P
, -P,).

In addition, in Figures 5 and 6, 1 to 4 are coefficients, '
1 to 8g indicates the determination level.

〔Effect of the invention〕

As explained above, in the case of the present invention, it is possible to stably control to the target value in power generation operation and pumping storage operation 0AFC operation, and not only has an extremely large effect on stability, but also has an extremely large effect on stability. In a pumped storage power generation system that generates electricity during the day and operates as pumped storage at night, it can operate efficiently with respect to the power required by the grid even during pumped storage operation, so its economic effects are extremely large.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams showing the system configuration of the variable speed pumped storage power generation system and an overview of its control, and Figure 3 is a diagram showing the state in which the variable speed power generation system is connected to the grid via a power transmission line. , K4 is a rounded diagram explaining the relationship between 7 Rancis turbine output and efficiency, and Figures 5 and 6 are diagrams showing examples of specific control flows during power generation operation and pumping operation, respectively. It is. E8...Excitation circuit, G...Variable speed power generation system, V
...Governor valve, PG...Speed generator, C...Control command section, T...Operation terminal, P...Active power calculation section, C
T...Current transformer, PT...Voltage transformer.

Claims (1)

[Claims] An operation control method in a variable speed power generation system in which an induction machine with primary and secondary excitation is operated at an arbitrary rotation speed, wherein when a power control command value is given from the outside, the command value The AC excitation voltage for the induction machine secondary winding is determined based on the difference between the predetermined target rotation speed and the actual rotation speed of the induction machine, and the difference between the power control command value and the output or input of the induction machine. A variable speed power generation system operation control method characterized by controlling the phase of a variable speed power generation system. 2. During power generation operation, if the power control command value is increasing, the rotation speed of the induction motor exceeds the target value, and if it is decreasing, the power control command value and induction motor are used until the rotation speed falls below the target value. After controlling the phase of the AC excitation voltage based on the difference between the output of the induction machine and the actual rotation speed of the induction machine, the phase of the AC excitation voltage is controlled based on the difference between the target rotation speed and the actual rotation speed of the induction machine, while power control is performed during pumping operation. If the command value is to decrease, the target rotation is continued until the absolute value of the induction motor input becomes less than the absolute value of the command value, and if the command value is to increase, the target rotation continues until the absolute value of the input exceeds the absolute value of the command value. After the phase of the AC excitation voltage is controlled based on the difference between the number of rotations and the actual rotation speed of the induction machine, the phase of the AC excitation voltage is controlled based on the difference between the power control command value and the input of the induction machine. A variable speed power generation system operation control method according to scope 1.