JP2538862B2 - Variable speed pumped storage power generation system controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control method of a variable speed power generation system for operating an induction machine with secondary excitation at an arbitrary rotation speed, and particularly to an automatic frequency of power generation and pumping. The present invention relates to an operation control method of a variable speed power generation system suitable for stable control to a target value during control (AFC) operation.

[Background of the Invention]

The conventional pumped storage power generation system is not able to adjust the load during pumping, the generated power required by the system changes during power generation operation, and the pump head operates during pumping operation. The drawback was that it changed.

Therefore, research is being conducted to operate the above system with the highest efficiency regardless of power generation and head.
The trend of research is moving toward the adoption of a so-called variable speed power generation system in which a pumped-storage power generator, which was a synchronous machine in the past, is used as an induction machine with secondary excitation and operates at a rotational speed other than the periodic speed. By adopting such a variable speed power generation system, it becomes possible to operate the system at the highest efficiency regardless of power generation and head. Therefore, various studies have been conducted to realize this variable speed power generation system. About this variable speed power generation system,
Introduced in the 5th Annual Meeting of the Institute of Electrical Engineers of Japan, No.553, "Variable speed operation characteristics of large capacity synchronous motors", no specific control method was mentioned.

[Object of the Invention]

An object of the present invention is to provide a control device for a variable speed pumped storage power generation system that can be operated with high efficiency in various operating states of power generation and pumped water, and that can be controlled to a stable target value during AFC operation.

[Outline of Invention]

A control device for a variable speed pumped storage hydropower system of the present invention connects a water turbine to an induction machine having a secondary winding connected to an electric power system, operates the water turbine at a variable speed setting, and controls the secondary winding. In a control device of a variable speed pumped storage hydropower system including secondary excitation control of a wire with electric power of a slip frequency, an active power command value of input and output to and from the induction machine is input, and the active power command value is responded to. The output value of the water turbine indicates a rotation speed command value, which is obtained and output according to preset active power and characteristic data of the maximum efficiency rotation speed, and the actual lift is input to the actual lift and the active power command. Command calculation means (15) for obtaining and outputting a command value of the guide vane opening degree of the water turbine based on the value and the command value of the rotational speed
An opening setting means (14) for outputting a set value of the vane opening to the turbine control means based on the guide vane opening command value output from the command calculating means, and a target output from the command calculating means. The difference between the rotation speed and the actual rotation speed of the water turbine and the difference between the power command value and the actual power of the induction machine are obtained, and the secondary excitation power required to bring these differences to zero or near zero is obtained. Phase difference angle calculating means (16) for obtaining the phase angle command value, and voltage adjusting means (18) for setting the amount of secondary excitation required to make the terminal voltage of the induction machine the reference voltage that is the target of the system.
And a secondary winding excitation amount setting means (17) for setting various amounts of excitation power of the secondary winding based on the set secondary excitation amount and the phase angle command value. And an exciting means (23) for exciting the secondary winding based on the amount of excitation.

Here, the operation of the present invention having the above configuration will be described.

First, in general, a variable speed pumped storage generator inputs and outputs the required active power, and thus it is natural to control the guide vane opening of the water turbine according to the active power.

However, the present invention has been made based on the finding that the turbine efficiency changes according to the output of the induction machine or the value of the input active power, and that the rotation speed at which the maximum efficiency is changed differs depending on the value of the active power. That is, the present invention presets the characteristic data of the maximum efficiency rotation speed with respect to active power,
The maximum efficiency rotation speed corresponding to the input command value of the active power is calculated, and the guide vane opening is controlled based on the calculated rotation speed. It can be operated with high efficiency.

Secondly, as a method of controlling the active power, in addition to controlling the absolute value of the excitation voltage, in the case of an induction machine, since it is AC excitation, the phase of secondary excitation is controlled, that is, the phase. It is possible to control the corners to control the active power.
Further, it is conceivable to combine and control these two elements. With respect to this point, in the present invention, the phase angle is controlled based on the effective power for the following reason. As is well known, the active power P and the reactive power Q of the variable speed pumped storage generator connected to the grid can be expressed by the following equations, respectively.

Here, E ₁ is the output voltage vector of the variable speed pumped-storage generator, E ₂ is the system voltage vector when the system side is considered as an infinite bus, X is the reactance of the line between them, θ
Is the phase angle between the variable speed pumped storage generator and the infinite bus.

On the other hand, in the normal operating range of pumped storage power generation, the displacement angle θ is small (for example, about 10 °), so if θ is changed in such a range, the reactive power Q is almost changed due to the difference between sin θ and cos θ. Instead, only the active power P can be controlled.

Further, since the active power can be controlled by controlling the excitation phase, it is possible to feedback-correct the rotation speed by utilizing this.

In view of such characteristics, the present invention determines at least the difference between the active power command value and the actual electric power of the induction machine, and also obtains the difference between the target rotational speed and the actual rotational speed of the water turbine, and the difference between them is zero or zero. The phase of the secondary excitation power is controlled so that they are close to each other. Thereby, according to the present invention,
The effective power P of the variable speed machine is reduced by reducing the influence on the grid.
In addition to the stable control of the rotational speed, the excitation phase control can control the rotational speed to a target value with good responsiveness. As a result, the variable speed pumped storage generator can be stably controlled to the target value during AFC operation.

Example of Invention

FIG. 2 is a diagram showing an outline of the variable speed power generation system, and is composed of three-phase windings on both the primary and secondary sides.

In the figure, 1 is a stator and 2 is a rotor. 5a ~
5c is a, b, c phase winding of the stator 1, and 6a to 6c are a, b, c of the rotor 2.
It is a phase winding. When the rated frequency is a slip and the slip is s, the speed of the rotor 2 is (1-s),
By exciting all of the excitation windings at a frequency of s,
The rotating magnetic field generated by the rotor 2 rotates at zero slip (synchronous speed) and becomes the same as the speed of the rotating magnetic field of the stator 1. Reference numeral 7 is a measuring unit for measuring the number of rotations of the rotor 2, the output from the measuring unit 7 is taken into the slip detecting unit 3, the slip frequency is detected by the detecting unit 3, and the detected signal is supplied to the voltage generating unit. Supply to 4. The voltage generator 4 generates a voltage according to the slip frequency and excites the secondary winding. By doing so, it is possible to always generate the voltage of the system frequency in the armature winding even when the operation is performed at an arbitrary rotation speed. That is, in the configuration of FIG. 2, the rotating magnetic field of the rotor is (1-s) + s = ... (1), and the output at the rated frequency is obtained regardless of slip.

In such a variable speed power generation system, it is an object of the present invention to provide a method capable of stably controlling a target value at an arbitrary rotation speed during AFC operation in pumping and power generation.

FIG. 3 is a block diagram showing the basic concept of this variable speed power generation system, and shows the case where the variable speed machine is connected to the system and is operating.

10 is an electric power system, and 1 and 2 show the same stator and rotor as in FIG. When the static difference H and the output command P ₀ are given to the command value calculation circuit 15, the command value calculation circuit 15 causes the command vane opening command value H _{v in} consideration of efficiency.
And the speed command value N ₀ are calculated. Reference numeral 14 is a valve opening setting device of the speed governor, and this opening setting device 14 delays the opening command value H _v from the command value calculation circuit 15 by time to determine the opening of the guide vane. The opening of the guide vane 13 of the water turbine is adjusted based on the output of the opening setter 14, and the opening and the static drop difference H
Based on the turbine characteristics, the rotor 2 connected to the turbine 12 rotates at the rotation speed N. 19 is a current transformer, 20
Indicates a voltage transformer, and the outputs from the current transformer 19 and the voltage transformer 20 are taken into the active power deriving unit 21, and the active power deriving unit 21 calculates the active power based on the output. To do. Reference numeral 116 is a phase angle calculation unit for the secondary winding. The phase angle calculation unit 116 outputs the output P of active power calculated by the active power derivation unit 21 and the speed command value from the command value calculation circuit 15.
N ₀ , the output command P ₀ , and the speed N from the speed generator 11 are taken in, and the phase angle of the secondary winding is calculated from them. 17
Is a setting unit that sets the excitation amount of the secondary circuit, and 18 is a voltage adjustment unit that controls the voltage value of the excitation amount. 23a-23c
Is a phase shift unit for shifting the amount of excitation set by the setting unit 17 for the a, b, and c phases. 22a to 22c are phase shifters 23a to 23c
It is an excitation winding that excites the a, b, and c phases according to the amount of excitation that is phase-shifted at.

Thus, the guide vane opening and speed target values are obtained for the output command value, and the phase angle of the secondary winding must be calculated from these values to perform control. The processing method and stable control method of the angle calculation unit 116 have not been established, and these need to be established. Therefore, in the present invention, the above-described control method is embodied with a configuration as shown in FIG.

FIG. 1 is a block diagram showing an embodiment of the present invention.
The case where the variable speed machine is connected to the system and is operating is shown.

The difference between the embodiment shown in FIG. 1 and the configuration shown in FIG. 3 is that the phase angle calculation unit 116 uses a target rotation speed N ₀ from the command value calculation circuit 15 and an actual rotation speed N from the speed generator 11. And a phase angle control amount calculation unit 25 that takes in the output calculated by the comparison unit 24 and calculates, for example, ∫k ₂ (N−N ₀ ) dt, and an active power derivation unit 21. From the output P and the difference between the output command value P ₀ , and a phase angle for calculating ∫k ₁ (P−P ₀ ) dt by taking in the output calculated by the comparison unit 26. The control amount calculation unit 27 and the phase angle control amount calculation unit 2
The point is that it is configured by an addition unit 28 that adds the outputs of 5, 27 and a phase angle calculation unit 16 that calculates the phase angle Δδ by the output from the addition unit 28. The output from the phase angle calculation unit 16 is supplied to the setting unit 17. In this way, the guide vane opening command value and speed command value are given to the output command value, and the difference between the actual rotational speed N and the target value N ₀ and the actual output P
And the target value P ₀ , the phase angle Δδ of the secondary winding is calculated, and the excitation amount is controlled by this value, so that stable control can be performed. That is, since the phase angle is controlled so that the difference between the actual rotation speed N and the target rotation speed N ₀ becomes zero, the water turbine or the like operates at the target rotation speed N ₀ with the highest efficiency.

Further, with respect to the change of the power command value, the guide vane opening command value Hv immediately changes, and the output of the mechanical system and the like changes. After that, the output of the electric system is controlled by the difference between the actual value of the rotation speed and the active power and the command value. in this way,
By delaying the control output of the electrical system, it is possible to coordinate changes in the mechanical system output that have a delay due to the inertia of the generator and other delay elements with changes in the electrical system with a fast response speed, and to achieve stable control. Can be done.

Hereinafter, a specific configuration example to which an embodiment of the present invention is applied will be described with reference to FIG.

FIG. 4 shows an example of a system in which a pumped-storage generator G ₁ in a so-called variable speed power generation system, which can be operated at an arbitrary rotation speed by an induction machine with secondary excitation, is connected to the grid 10 via a transmission line L. It is a system diagram shown.

In the figure, a voltage transformer 20 and a current transformer 19 are installed on a transmission line L.

Generally, the pumping generator G _1, Francis turbine is used, the relationship between the water turbine output and efficiency is shown as in FIG. 5. In this figure, the horizontal axis indicates the turbine output, the vertical axis indicates the efficiency, and the number of revolutions is shown as a parameter. P ₁ and P ₂ indicate turbine output, η ₁ and η ₂ indicate efficiency, and N ₁ and N ₂ indicate rotational speed. The turbine efficiency is the ratio of the turbine output to the hydraulic energy that acts on the turbine. Further, if the loss of the induction machine composed of the stator 1 and the rotor 2 is ignored, the turbine output has a relationship corresponding to the output P of active power. Output P ₁ rpm N ₁ In, at a rotational speed N ₂ at output P _2, the maximum efficiency η at each output
₁ and η ₂ .

As described above, the number of revolutions at which the efficiency becomes maximum differs depending on the output, and the present invention intends to operate at the point of these maximum efficiency.

In Figure 4, the variable speed generator systems, from the operating end T, the generating capacity required for the generator G ₁ command (or target value)
Given P ₀ , in consideration of the characteristics of the generator G ₁ and the head of water, the number of revolutions N ₀ of the generator G ₁ and the opening H of the guide vane of the turbine are set so as to enable highly efficient operation. _v is obtained by the control command unit C, and operation is performed so as to meet these values (N ₀ , H _v ). Here, the control command section C is composed of the above-mentioned elements 13, 14, 16-18, 24-28. In such a state, when a command to decrease the generator output is given from the operating end T, a method given in advance to the control command unit C is used to generate the generator output P and the water drop,
The number of revolutions N ₀ and the valve opening H _{v of the} guide vanes are calculated so that the efficiency η of the generator becomes the highest, and the phase angle of the secondary AC excitation is adjusted so that these (N ₀ , H _v ) become the target values. Δδ is controlled,
Efficient operation will be performed.

On the other hand, the deviation of the rated speed of the generator G ₁ is given from the control instruction unit C as the information for the excitation circuit E _x, as described above by using the slip frequency as the information, the output of the rated frequency Will be obtained.

Next, a specific example of the secondary excitation that is excited at the slip frequency will be described. As shown in FIG. 1, the signal applied to the three-phase secondary excitation winding is represented by the following equation (2).

That is, the phase angle Δδ of the function for obtaining the excitation amounts of the a to c phases is calculated by the phase angle calculation unit 116 by the command P ₀ given from the operation end T of FIG. When the phase angle Δδ obtained by the phase angle calculation unit 116 is given to the setting unit 17, the excitation voltages v _fa , v _fb , v _fc of the a to c phases are Is required. Here, E is a voltage value determined by the slippage and the operating state of the variable speed machine, t is time, δ ₀ is a phase angle determined by the operating state of the variable speed machine, and Δδ is a phase angle controlled by the output of the control command unit C. And

When the control is performed using the above equation, the voltage E may be used for the reactive power control command, and the phase angle Δδ may be used for the active power control command.

The present invention stably controls active power to a target value during AFC operation in the above formula (2).

Therefore, in the above configuration, by controlling the phase angle of the excitation circuit E _x a (.DELTA..delta), must match the rotational speed N and power P to the target value. Therefore, it can be understood that the active power P and the rotation speed N may be used as the information for moving the phase angle Δδ.

Therefore, in the embodiment of the present invention, the phase calculation unit 116 is configured as shown in FIG. 1 to realize the following expression (3).

That is, the phase angle Δδ is calculated as Δδ = −∫k ₁ (P−P ₀ ) dt + ∫k ₂ (N−N ₀ ) dt (3). Here, P ₀ is a target value of active power (power control command value), N ₀ is a target value of rotation speed, P is an actual value of active power, N is an actual value of rotation speed, k ₁ and k _2. Is a constant.

Further, the calculation process of the above equation (3) will be described with reference to FIG.

The difference (N−N ₀ ) between the actual rotation speed N and the target value N ₀ is calculated by the comparison unit 24. The output (N−N ₀ ) calculated here is supplied to the phase angle control amount calculation unit 25, and the calculation unit 25 calculates Δk ₂
(N−N ₀ ) dt is calculated.

On the other hand, the difference between the actual value P of active power and the target value P ₀ (P−
P ₀ ) is calculated by the comparison unit 26. The output (P−P ₀ ) calculated by the comparison unit 26 is supplied to the phase angle control amount calculation unit 27, and the calculation unit 27 calculates −∫k ₁ (P−P ₀ ) dt.

The outputs from the calculating units 25 and 27 are added by the adding unit 28 {-∫k ₁ (P-P ₀ ) dt + ∫k ₂ (N-N ₀ ) dt}.

The value calculated in this way is given to the setting unit 71, and the setting unit 17 calculates the equation (2).

In the above-mentioned embodiment, the phase angle Δδ is calculated by the equation (3).
In the second embodiment, the following formula (4) may be calculated, and in the third embodiment, the formula (5) may be calculated. It is a thing.

Δδ = −k ₁ (P−P ₀ ) + k ₂ (N−N ₀ ) ... (4) Δδ = −∫k ₁ (P−P ₀ ) dt + ∫k ₂ (N−N ₀ ) dt −K ₁ ( P−P ₀ ) + K ₂ (N−N ₀ ) ... (5) Here, K ₁ and K ₂ are constants.

According to the second and third embodiments, the same operational effect as the first embodiment can be obtained.

〔The invention's effect〕

According to the present invention, the characteristic data of active power and maximum efficiency rotation speed is set in advance, the maximum efficiency rotation speed corresponding to the command value of the input active power is calculated, and the guide speed is determined based on this calculated rotation speed. Since the vane opening is controlled, it is possible to obtain a special effect of always operating with high efficiency even if the active power command value changes.

In addition, the difference between the active power command value and the actual power of the induction machine and the difference between the target rotational speed of the water turbine and the actual rotational speed are calculated, and the secondary excitation power of the secondary excitation power is adjusted so that these differences become zero or near zero. Since the phase is controlled, the variable speed machine can be stably controlled according to the surplus or shortage of the active power P command value without affecting the reactive power, and the rotation speed is controlled to the target value with good responsiveness. it can. As a result, the variable speed pumped storage generator can be stably controlled to the target value during AFC operation.

Further, even during the pumping operation, the electric power required by the system can be efficiently operated, and the economical effect is extremely large.

[Brief description of drawings]

1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing an outline of the principle of a variable speed pumped storage power generation system, and FIG. 3 is a block diagram showing an outline of a control system of the variable speed pumped storage power generation system. FIG. 4 is a block diagram showing a specific configuration example of the variable speed power generation system to which the embodiment of the present invention is applied, and FIG. 5 is a diagram showing the relationship between output and efficiency. Ex _: Excitation circuit, G _1: Variable speed generator generator,
L: Transmission line, C: Control command unit, T: Operation terminal, 1 ...
... stator, 2 ... rotor, 3 ... slip detector, 4 ...
Voltage generators, 5a to 5c: stator a to c phase windings, 6a to 6c
... a-c phase winding of rotor, 7 ... rotation speed measuring unit, 10 ...
… Grid, 11 …… Speed generator, 13 …… Guide vane, 14…
… Opening degree setter, 15 …… Command value calculation circuit, 16 …… Secondary winding phase angle calculation unit, 17 …… Secondary winding excitation amount calculation unit, 18 …… Voltage adjustment unit, 19 …… Current transformation 20, voltage transformer, 21 ...
… Active power deriving unit, 22a-22c… Second excitation a-c phase winding, 23a-23c… Phase shift unit, 24,26… Comparing unit, 25,27…
Phase angle control amount calculation unit, 28 ... Addition unit, 116 ... Phase angle calculation unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeharu Ishibashi 3-3-22 Nakanoshima, Kita-ku, Osaka City, Kansai Electric Power Co., Inc. (72) Inoura Norio 4026, Kujimachi, Hitachi Hitachi Manufacturing Co., Ltd. Inside Hitachi Research Laboratory (72) Inventor Masuo Goto 4026 Kuji Town, Hitachi City Hitachi Ltd. Inside Hitachi Research Laboratory (56) Reference JP-A-59-72998 (JP, A)

Claims (4)

(57) [Claims] 1. A water turbine is connected to an induction machine having a secondary winding connected to a power system, the water turbine is operated at a variable speed of setting, and the secondary winding is driven by electric power of a slip frequency. In the control device of the variable speed pumped storage power generation system including the secondary excitation control, inputting the active power command value of the input and output to the induction machine,
The output value of the water turbine corresponding to the active power command value indicates a rotation speed command value indicating the maximum efficiency, is output according to preset active power and maximum efficiency rotation speed characteristic data, and the actual head is input. Command calculation means (15) for obtaining and outputting a command value of the guide vane opening degree of the water turbine based on the actual head, the active power command value and the command value of the rotation speed, and the command calculation means (15) An opening setting means (14) for outputting a set value of the vane opening to the turbine control means based on the guide vane opening command value, a target rotation speed output from the command calculation means, and an actual rotation speed of the water turbine. Phase difference angle calculating means for obtaining a difference and a difference between the power command value and the actual power of the induction machine, and for obtaining a phase angle command value of the secondary excitation power required to bring these differences to zero or near zero. (16) and the terminal voltage of the induction machine Voltage adjustment means for setting the secondary excitation amount required to reference voltage the target (18)
And a secondary winding excitation amount setting means (17) for setting various amounts of excitation power of the secondary winding based on the set secondary excitation amount and the phase angle command value. A control device for a variable speed pumped storage hydropower system, comprising: an excitation means (23) for exciting the secondary winding based on the amount of excitation. 2. The control device for a variable speed pumped storage power generation system according to claim 1, wherein the phase angle command value Δδ is obtained by the following equation. Δδ = −∫k ₁ (P−P ₀ ) dt + ∫k ₂ (N−N ₀ ) dt where P is the induction machine power, P ₀ is the power command value, N is the actual speed, and N ₀ is the target speed. , K ₁ and k ₂ are constants. 3. The control device for a variable speed pumped storage hydropower system according to claim 1, wherein the phase angle command value Δδ is obtained by the following equation. Δδ = −k ₁ (P−P ₀ ) + k ₂ (N−N ₀ ), where P is the induction machine power, P ₀ is the power command value, N is the actual speed, N ₀ is the target speed, k ₁ , k ₂ is a constant. 4. The control device for a variable speed pumped storage hydropower system according to claim 1, wherein the phase angle command value Δδ is obtained by the following equation. Δδ = −∫k ₁ (P−P ₀ ) dt + ∫k ₂ (N−N ₀ ) dt −K ₁ (P−P ₀ ) + KJ (N−N ₀ ), where P is induction motor power and P ₀ is A power command value, N is an actual rotation speed, N ₀ is a target rotation speed, and k ₁ , k ₂ , K ₁ , and K ₂ are constants.