JPH0636679B2 - Variable speed pumped storage power generation system controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for a variable speed pumped storage hydropower system that operates a synchronous excitation machine with secondary excitation at an arbitrary number of revolutions. The present invention relates to a control device for a variable speed pumped storage power generation system, which is suitable for suppressing fluctuations in terminal voltage even when a large disturbance occurs on the secondary side.

[Conventional technology]

The conventional pumped storage power generation system has a low system efficiency due to the fact that the load cannot be adjusted during pumping, the power generation required by the grid changes during power generation operation, and the head changes during pumping operation. The drawback was that it changed.

Therefore, research is being conducted to operate the above system at the highest efficiency regardless of the power generation and the head. The trend of this research is to move toward the adoption of a so-called variable speed power generation system that operates a pumped-storage generator, which was a conventional DC-excited synchronous machine, at a low frequency and operates at a rotational speed other than the synchronous speed. There is. 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, and there are documents such as Japanese Patent Laid-Open No. 61-98187 "Operation control system". )
It was found that the current is affected by the electron-electron reaction and the terminal voltage and active power fluctuate significantly. Even the measures against this were not taken into consideration.

FIG. 2 shows an outline of constant current control conventionally used for excitation control of a variable speed pumped storage power generation system. 1 is a stator of a variable speed machine, 2 is a rotor, and 22a to 22a.
Reference symbol c denotes windings a to c of the rotor, and reference symbols 23a to 23c denote constant current control units. In the figure, the voltage transformer 20 takes in the terminal voltage of the variable speed machine, and the secondary winding excitation amount setting unit 17 and the excitation amount adjusting unit 18 set the reference amount of the excitation current in the operating state. To be done. This output and the rotor currents of the variable speed machine obtained by the current transformers 24a to 24c are compared in the comparison units 26a to 26C, and the output is multiplied by the gain of the constant current control system, and the rotor current is the reference amount. The current is controlled to the value specified in.

When the variable speed machine G ₁ as shown in FIG. 3 is connected to the system A via the power transmission line L and is operating by using the system that performs such excitation control, the point F of the power transmission line L is used. If an accident occurs, the change in the current on the stator side of the variable speed machine appears in the rotor side current due to the armature reaction. For this reason,
The rotor side current changes greatly, the difference between the reference amount of the constant current control system and the rotor current increases, and the terminal voltage and active power fluctuate significantly even after the accident is removed. In this way, no consideration was given to suppressing fluctuations in the terminal voltage and active power in the event of a system fault.

Here, the current transformer CT ₁ , the voltage transformer PT ₁ , the active power calculation unit P, the excitation control unit Ec, the control command unit C, the operating end T, the exciter Ex, the governor valve 13 and the like operate the variable speed system. It has the necessary functions and will be described in detail later.

[Problems to be solved by the invention]

As described above, in the above-described conventional technology, the control device is not considered in consideration of the fact that the secondary excitation (rotor) current is affected by the armature reaction in the event of a system fault, and is affected by the armature reaction in the event of a fault. There was no need to establish a control unit.

The present application compensates for the above drawbacks, and in a variable speed pumped storage power generation system that operates with high efficiency in various pumping and power generation operating states, it is possible to reduce fluctuations in the terminal voltage and reduce fluctuations in the excitation circuit during a grid fault. Another object of the present invention is to provide a variable speed pumped storage power generation system control device.

[Means for solving problems]

According to the present invention, an operating condition in which an arbitrary power generation is obtained is an effective head,
Determined from the relationship between the rotation speed and the governor opening.
Of these operating conditions, the efficiency of the system is determined by the number of revolutions, and the number of revolutions is determined by the difference between the turbine input and the generator output. In addition to controlling, the internal phase angle is controlled to match the generator output with the command value, and the difference between the flux linkage number obtained by measurement and the value (flux linkage number) given in advance as a reference is taken, It is an object of the present invention to achieve the above-mentioned object by giving a value obtained by multiplying this value by a gain as a secondary excitation voltage so as to reduce the perturbation of the excitation system during a system fault.

[Action]

FIG. 4 shows an outline of the variable speed power generation system, which comprises three-phase windings on both the primary and secondary sides.

In the figure, 1 is a stator and 2 is a rotor. 5a-5c
Shows the a, b and c phase windings of the stator, and 6a to 6c show the a, b and c phase windings of the rotor. Further, if the rated frequency is S and the slip is S, the speed of the rotor is (1-S), and by exciting the exciting winding of the rotor at the frequency of the slip S, the rotating magnetic field of the rotor has zero slip. It rotates at (synchronous speed) and becomes the same as the rotating magnetic field speed of the stator. Reference numeral 7 denotes a measuring unit for measuring the number of rotations of the rotor.
3 shows that the slip frequency is detected, and when 4 the voltage corresponding to the slip frequency is generated to excite 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 example of FIG. 4, the rotating magnetic field of the rotor is (1−S) + · S = ... (1), and an output at the rated frequency is obtained regardless of slip.

In such a system, as shown in FIG. 5, the secondary excitation voltage is controlled by measuring the flux linkage numbers _ada , _adb ,
_adc and the amount determined in advance according to operating conditions
Comparing units 29a to _29c with the differences between _ada0 , _adb0 , and adc0
Thus, by using the value obtained by multiplying this value by the gain K as the secondary excitation voltage to perform the excitation, stable control can be performed without giving disturbance to the excitation system even in the event of a system fault. The method for measuring the number of magnetic flux linkages will be described later.
Here, 1, 2, 17, 18, 20, 22a to 22c are the same as in FIG. 2, the stator, the rotor, the control amount setting unit (excitation amount setting unit), the excitation amount adjusting unit, the voltage transformer, and the rotation. Child ac
The phase winding is shown.

[Embodiment] FIG. 1 shows a specific example of the present system, and shows a case where a variable speed machine is connected to a system and is operating. S
Shows 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, the command value calculation circuit 15 calculates the governor valve opening command value and speed command value in consideration of efficiency. Reference numeral 14 is a valve opening setting device of the speed governor, and the opening command value from the command value calculation circuit 15 becomes the valve opening 13 of the speed governor with a time delay by the opening setting device 14. Reference numeral 12 is a water turbine portion, and its characteristics are determined by the static difference H, the valve opening 13 of the speed governor, and the rotation speed N. The rotor 1 of the variable speed machine is rotated by the input obtained by this water wheel characteristic. Reference numeral 11 denotes a speed generator, and the speed N is detected by this output. 19 is a current transformer, 2
Reference numeral 0 indicates a current transformer, and reference numeral 21 calculates active power based on the outputs of the current transformer 19 and the current transformer 20.

Reference numeral 16 denotes a secondary winding phase angle calculation unit that calculates the output P of the active power calculation unit 21, the output command value P ₀ , the speed command value N ₀ , and the speed N. Reference numeral 17 is a setting unit for setting the excitation amount of the secondary circuit, and 18 is an excitation amount adjusting unit for controlling the absolute value of the excitation amount.

23a to 23c are based on the excitation amount set in 17,
This is a part that creates the excitation amounts of the a, b, and c phases. 22a-22
c is an excitation winding for exciting the a, b, and c phases by the excitation amounts calculated by the excitation amount creating units 23a to 23c. SC indicates a search coil and IC indicates an integrating circuit, and the number of flux linkages, which is the output of the integrating circuit IC, is introduced into the secondary winding excitation amount setting unit 17.

For the measurement of the number of magnetic flux linkages used here, for example, as shown in FIG. 6, a search coil SC is provided on the surface of the rotor R ₀ , and the voltage induced in this coil SC is integrated by an integrating circuit IC. , Common magnetic flux between stator winding and rotor winding
_{Find ad} , find the common magnetic flux for each phase based on this value, take the difference between this value and the reference amount that was determined in advance according to the operating state, multiply this value by the gain, and use this value as the excitation voltage. Is to control as.

That is, the magnetic flux _ad obtained here is phase- _shifted and converted into each phase amount, and the magnetic fluxes _ada , _adb , and _adc are obtained. At the same time, considering the operating conditions, the reference amount of each phase magnetic flux _ada0 ,
_adb0 and _adc0 are shown in FIG.
As shown in FIG. 5, the difference between the measured value of the magnetic flux and the reference amount is obtained by the comparison units 29a to 29c, this value is multiplied by the gain to obtain the excitation voltage, and this voltage is It is applied to the rotor windings 22a to 22c.

The output of the search coil SC provided on the rotor R ₀ shown in FIG. 6 may be taken out through the slip ring.

Here, the following equation holds for the common magnetic flux _ad between the stator winding and the rotor winding. _{ad = x ad (-i d +} i fd) ... (2) where, x _ad: mutual reactance, _{I d:} stator d-axis current, i _fd: a rotor d-axis current.

As is clear from the equation (2), _ad cancels the influence of the stator current in the d-axis current of the rotor. Therefore, the influence of the stator on the rotor side appears due to the system side accident. Absent. Therefore, even if an accident occurs on the system side, it is possible to suppress the disturbance of the exciting magnetic flux caused by the armature reaction.

An embodiment of the present invention will be specifically described below with reference to FIG.

FIG. 3 shows that a so-called variable speed pumped storage power generation system G ₁ that operates a synchronous machine that excites a secondary with a low-frequency alternating current at an arbitrary rotation speed is connected to a grid S via a power transmission line L and operated. It shows an example. In the transmission line L, the voltage transformer PT
₁ , the current transformer CT ₁ is installed.

Generally, Francis turbines are used for pumped storage generators,
The relationship between turbine output and efficiency is shown in Fig. 7. This figure shows the turbine output on the horizontal axis and the efficiency on the vertical axis, and shows the number of revolutions as a parameter. P ₁ and P ₂ represent turbine output, η ₁ and η ₂ represent efficiency, and N ₁ and N ₂ represent rotational speed. The output P ₁ is the rotation speed N ₁ , and the output P ₂ is the rotation speed N 1.
_2, shows that become maximum efficiency eta _1, and eta ₂ at each output. In this way, the number of revolutions at which the efficiency becomes maximum differs depending on the output, and the feature of this system is that the system tries to operate at these maximum efficiency points.

In FIG. 3, the variable-speed pumped storage hydropower system G ₁ receives a control command of the power generation required for the system from the operating end T, and considers the characteristics of the generator and the water drop, and To enable efficient operation, the control command unit C obtains the number of revolutions of the generator and the opening degree of the governor valve V of the turbine.
It is controlled so that driving that meets these values can be performed. In this condition, when the generator output reduction command is given, the rotation speed and valve opening are adjusted by the method given in advance so that the generator efficiency is maximized based on the generator output and head. Will be controlled and efficient operation will be performed.

On the other hand, the deviation from the rated speed of the generator is due to the excitation circuit Ex.
As described above, by giving the slip frequency from the excitation controller Ec, the output of the rated frequency can be obtained as described above.

Next, a specific example of secondary excitation will be described. As shown in FIG. 1, the three-phase secondary excitation winding is represented as follows. That is, the phase angle Δδ of the function for obtaining the excitation amounts of the a, b, and c phases is obtained by the command given from the operation end T of FIG. The excitation voltages of the a, b, and c phases are v _fa ,
If v _fb and v _fc , Is represented. Here, E is a voltage value determined by the operating state of the slip and variable speed machine, δ ₀ is a phase angle determined by the operating status of the variable speed machine, and Δδ is a controlled phase angle of the output of the control command unit. When the control is performed using the above formula, the control command for the reactive power may be controlled by the voltage E, and the control command for the active power may be controlled by the phase angle Δδ.

By doing so, the rotor winding can be excited without being affected by the accident on the system side, and thus the fluctuation of the terminal voltage can be controlled, and in addition, AFC (automatic frequency control) during steady state, As for the operation such as AQR (automatic reactive power control), it can respond at high speed.

〔The invention's effect〕

According to the present invention, in a variable speed pumped storage hydropower system, fluctuations in the terminal voltage at the time of a system fault can be suppressed, so the practical effect is extremely large.

Furthermore, in order to replenish or consume fluctuations in electric power, in a pumped storage power generation system that operates as power generation during the daytime and as pumped water at night, it is possible to efficiently operate the various types of power required by the grid, which is an economic effect. Is also big.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a variable speed pumped storage power generation system according to the present invention, FIG. 2 is a diagram showing an outline of a conventional constant current control system, and FIG. 3 is a variable speed pumped storage power generation system to which the present invention is applied. FIG. 4 is a diagram showing an outline of the control of FIG. 4, FIG. 4 is a diagram showing an outline of the principle of the variable speed pumped storage power generation system, and FIG.
FIG. 6 is a diagram showing a method for measuring the number of magnetic flux linkages, and FIG. 7 is a diagram showing the relationship between output and efficiency. Ex ... Exciter, G ₁ ... Variable speed power generation system, L ...
... transmission line, S ... system, C ... control command section, T ... operating end, 1 ... stator, 2 ... rotor, 3 ... slip detection section, 4 ... voltage generation section, 5a ... 5c: Stator a,
b, c phase windings, 6a to 6c ... Rotor a, b, c phase windings, 7 ... Rotation speed measuring section, 11 ... Speed generator, 12 ...
... water turbine part, 13 ... valve opening degree, 14 ... valve opening degree setter of speed governor, 15 ... command value calculating circuit, 16 ... secondary winding phase angle calculating part, 17 ... secondary winding Line excitation amount setting unit, 18 ... Excitation amount adjusting unit, 19 ... Current transformer, 20 ... Voltage transformer, 21 ... Active power calculation unit, 22a to 22c ... Secondary excitation a, b, c Phase winding, P ₀ ... Output command value, N ₀ ...
... speed command value, N ... speed, 23a to 23c ... constant current control unit, 24a to 24c ... current transformer, 25a to 25
c ... Gain of constant current control unit, 26a to 26c ... Comparison unit, 27 ... Voltage transformer, 28 ... Current transformer, ST ...
... Stator, R ₀ ... Rotor, K ... Gain, SC ... Search coil, IC ... Integration circuit, _ad ... Common magnetic flux between armature winding and rotor winding, 29a to 29c ... Comparison unit, Ec ... Excitation control unit.

Front page continuation (72) Inventor Eiji Haraguchi 3-3-22 Nakanoshima, Kita-ku, Osaka-shi, Osaka Kansai Electric Power Co., Inc. (72) Hiroto Nakagawa 3-22-3 Nakanoshima, Kita-ku, Osaka-shi, Osaka Kansai Electric Power Co., Inc.

Claims (1)

[Claims] 1. A variable speed generator having a three-phase stator winding connected to a power system and a three-phase rotor winding excited by an alternating current, and driven by a water turbine to supply power to the power system. A search coil provided in the rotor for measuring an induced voltage generated between the stator winding and the rotor winding; an integrating circuit that integrates the induced voltage and outputs a common magnetic flux; A secondary winding that performs phase shift conversion on the common magnetic flux output from the rotor and the magnetic flux reference amount of the rotor obtained from the operating conditions of the variable speed generator, and outputs the phase-shifted rotor for each phase of the rotor. An excitation amount setting unit, a constant current control unit that obtains a difference between the output common magnetic flux and the magnetic flux reference amount for each phase, amplifies the difference, and outputs the amplified difference to each rotor, From the variable speed generator, the same frequency as that of the power system is applied to the rotation speed of the water turbine. Control device for a variable speed pumped storage power generating system and controlling so as to be independently outputted.