JPS5951215B2 - Synchronous machine step-out prediction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an out-of-step measurement method for a synchronous machine that detects that the synchronous machine is in a dangerous state where there is a risk of out-of-step and predicts out-of-step.

When a synchronous machine connected to an electric power system goes out of synchronization (out of synchronization), there is a risk that the entire system will fall into disorder.

Therefore, if the synchronous machine is in a dangerous state where it may lose synchronization, it is necessary to take measures such as performing field control to prevent the synchronization machine from going out of synchronization or separating the synchronous machine from the system. As a conventional synchronous machine step-out detection method,
A combination of power relay and impedance relay is used.

As shown in Fig. 1, if the horizontal axis represents the resistance component R and the vertical axis represents the reactance component X, then the power relay W passes through a specified set point a on the R axis. The power relay W operates in the hatched area in the figure with the limit being a straight line parallel to the axis. operates in a hatched area with the limit being a straight line parallel to the vertical axis passing through a predetermined set point -a on the R axis, and the impedance relay Z operates at a predetermined impedance Z (■"VFT marker, The machine is configured to operate within a circle with a radius of The equivalent impedance is the position Z during normal operation.When moving from the point along the trajectory shown by the curve l, the power relays W, , W. and the impedance relay Z
The step-out detection sequence circuit (
(not shown) is operated to detect a step-out condition. However, this conventional method is a method for detecting synchronization after the synchronous machine has lost synchronization, and does not have a function of detecting synchronization in a dangerous state where synchronization may occur.

Further, as a conventional method having a shut-off measuring function, a shut-off measuring method using a stability limit control relay has been used.

For example, in the case of a synchronous generator, as shown in Figure 2, the horizontal axis represents active power P, the vertical axis represents reactive power Q, and the output limit curve of the synchronous generator is L. When the stability limit curve is defined as m, a stability limit control relay G is provided that operates in the hatched area with curve g as the limit, and the vector coordinate W (=
P+JQ) is W when operating normally. When the trajectory shown by the curve s is drawn from the point and the stability limit curve g is crossed and the transition is in the direction of the out-of-step region, the excitation of the synchronous generator is strengthened by the conduction of the stability limit control relay G and the output vector coordinate W is set to normal. It is configured to return the motor to a normal position and prevent it from shifting to an out-of-step state. However, both the out-of-step measurement method using this stability limit control relay and the out-of-step detection method using a combination of a power relay and an impedance relay described above are based on the external electrical quantities of the synchronous machine (terminal voltage, output current, impedance, output, reactive power, phase difference angle, etc.) is used as the detection input and is not based on the abnormal state of physical quantities inside the synchronous machine, so it is difficult to say whether the detection result corresponds to the actual state of the synchronous machine. There are some interesting drawbacks.

Therefore, as a result of various studies and tests, the inventors found that
As shown in FIG. 3, the direct-axis magnetic velocity φ of the air gap before transition to step-out.

They found that the horizontal axis magnetic velocity φ and the horizontal axis magnetic velocity change significantly, and found that it is possible to predict out-of-step by detecting both the functional value of the vertical axis magnetic velocity and the functional value of the horizontal axis magnetic velocity. SUMMARY OF THE INVENTION Accordingly, a general object of the present invention is to provide a method for measuring out-of-step of a synchronous machine that can accurately predict that the synchronous machine is in a dangerous state in which there is a possibility of out-of-step.

In order to achieve this objective, the present invention detects the direct axis magnetic flux and horizontal axis magnetic flux of the air gap in the synchronous machine, and detects that at least one of the direct axis magnetic flux and the horizontal axis magnetic flux has decreased below a predetermined reference level. Or, the operating point of the synchronous machine given by the direct-axis magnetic flux and the horizontal-axis magnetic flux is outside the predetermined range due to the decrease rate of at least one of the direct-axis magnetic flux and the horizontal-axis magnetic flux increasing below a predetermined reference level. It is characterized by detecting and predicting loss of synchronization.

In the detuning measurement method of the synchronous machine, the horizontal axis magnetic flux φ, and the vertical axis magnetic flux φ.

Step-out can be predicted by detecting that the ratio φq←1 has increased beyond a predetermined reference level. Also, the direct axis magnetic flux φ.

and horizontal axis magnetic flux φ. The product φ. Step-out can be predicted by detecting that ×φq has decreased below a predetermined reference level. Further, step-out can be predicted by detecting that either the direct-axis magnetic flux φ or the horizontal-axis magnetic flux φq has decreased below a predetermined reference level.

Also, the direct axis magnetic flux φ.

To predict step-out by detecting that either the rate of decrease in (-dφ.←d,) or the rate of decrease in horizontal axis magnetic flux φq (-dφ, -d,) has increased to or above a predetermined reference level. I can do it. Also, the direct axis magnetic flux φ.

It is possible to predict a step-out by detecting that the absolute values of the horizontal axis magnetic flux φq and the horizontal axis magnetic flux φq both tend to decrease. next.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The synchronous machine detuning measurement method according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 4 shows a control circuit of a synchronous generator, reference number 10 indicates the synchronous generator, and the armature terminal of the synchronous generator 10 has an impedance of 1.
2 to the power grid 14. In addition, synchronous generator 1
The armature terminal of 0 is connected to the input terminal of the voltage deviation detector 16 via the voltage transformer 18, the reference voltage source Vs is connected to the voltage deviation detector 16, and the output terminal of the voltage deviation detector 16 is connected to the input terminal of the voltage deviation detector 16 via the voltage transformer 18. Connected to the input terminal a' of the arithmetic unit 20. Furthermore, an excitation system auxiliary device 22 such as a vibration suppressing stabilizer is connected to the input terminal b of the addition calculator 20. On the other hand, an air gap magnetic flux detection device 24 and a direct axis/horizontal axis position detector 26 are installed inside the synchronous generator 10.

The output terminal of the air gap magnetic flux detection device 24 includes a waveform analyzer 28 for analyzing fundamental waves, etc., a direct axis/horizontal axis magnetic flux analyzer 30, a division operator 32, a signal level comparator 34, an amplifier 34, and an amplifier 36. It is connected to the input terminal of the waveform analyzer 28 through the input terminal a of the detuning measuring device 38. In addition, the direct axis
The output terminal of the horizontal axis position detector 26 is connected to one input terminal m of the direct axis/horizontal axis magnetic flux analyzer 30 via the input terminal b of the detent measuring device 38, and the output terminal of the waveform analyzer 28 is directly connected shaft·
The straight-axis magnetic flux output terminal a1 and the horizontal-axis magnetic flux output terminal A2 of the straight-axis/horizontal-axis magnetic flux analyzer 30 are connected to the other input terminal n of the horizontal-axis magnetic flux analyzer 30, respectively, and are connected to the input terminal P1 and the horizontal-axis magnetic flux output terminal A2 of the division calculator 32, respectively. Connect to P2. The output terminal of the division operator 32 is connected from the output terminal C of the detuning measuring device 38 to the input terminal C of the addition operator 20 via a signal level comparator 34 and an amplifier 36. The output terminal of the adder 20 is connected to the input terminal of the automatic voltage regulator 40, and the output side of the automatic voltage regulator 40 is connected to the field winding 10a of the synchronous generator 10 via the excitation device 42.

Next, the system of the present invention will be explained along with the operation of the circuit configured as described above.

The generator terminal voltage generated by the synchronous generator 10 is supplied to the voltage deviation detector 16 via the voltage transformer 18 and compared with a predetermined reference voltage V8.
At the same time, the output of the excitation system auxiliary device 22 is supplied to the input terminal b of the addition calculator 20 and added thereto, and the output of the addition calculator 20 is supplied to the input terminal a of the automatic voltage regulator 4.
0 input terminal. The automatic voltage regulator 40 supplies an output corresponding to the input to the excitation device 42, and the synchronous generator 1
0 terminal voltage becomes a value corresponding to a predetermined reference voltage V, is supplied to the field winding 10a of the synchronous generator 10, and the synchronous generator 10 generates a voltage of a predetermined magnitude. It is operated in synchronization with the electric power system]4. In this case, the air gap magnetic flux φ, detected by the air gap magnetic flux detection device 24 is supplied to the waveform analyzer 28, and only the fundamental wave component is extracted and supplied to one input terminal a of the vertical axis/horizontal axis magnetic flux analyzer 30. At the same time, the position of the rotor with respect to the vertical axis and horizontal axis at each instant is detected by the vertical axis/horizontal axis position detector 26, and the position detection signal is sent to the other input terminal m of the vertical axis/horizontal axis magnetic flux analyzer 30. supplied to In the direct-axis/horizontal-axis magnetic flux analyzer 30, each instantaneous direct-axis magnetic flux φ and horizontal-axis magnetic flux φ are analyzed based on the inputs supplied to the input terminals m and n.
9 is supplied from the output terminals a1 and A2 to the input terminals P1 and p of the division calculator 32, and the ratio φ, /φ, between the horizontal axis magnetic flux φ9 and the vertical axis magnetic flux φ9 is calculated, and the calculated output is used for signal level comparison. is supplied to the input terminal of the device 34. Horizontal axis magnetic flux φ9
As can be easily understood from FIG. 3, the ratio φ, /φ, of the direct axis magnetic flux φ, is the coordinate point Φ during normal operation.

The signal level comparator 34 increases as it moves in the direction of the "A" part by drawing a trajectory 1 from 1.However, when the input signal is below a predetermined reference level R, the output becomes zero. Therefore, when the synchronous generator 10 is in a normal state, that is, when it is not in a dangerous state where it will shift out of synchronization, the signal level comparator 34 maintains the state where the output is zero, and the amplifier 36 outputs an addition signal. Since no input is supplied to the input terminal C of the arithmetic unit 20, the synchronous generator 10 is operated without correcting the excitation current. Ah, a dangerous situation has occurred, and the coordinate point Φ in Fig. 3 moves to the ゜“A゛” part of locus 1, and the ratio φ9/φ of the horizontal axis magnetic flux φ9 and the vertical axis magnetic flux φ exceeds the reference level R. When the increase exceeds R, the output signal indicating that a dangerous condition has occurred at the output terminal of the signal level comparator 34 is amplified by the amplifier 36 and sent from the output terminal of the de-adjustment measuring device 38 to the addition calculator. 20 input terminals C
supplied to

Therefore, the output of the adder 20 increases, the automatic voltage regulator 40 strengthens the excitation of the field winding 10a via the excitation device 42, and the synchronous generator 10 is prevented from going out of step.
The product φ6×φ9 is detected instead of the ratio φ, /φ6 of the horizontal axis magnetic flux φ9 and the vertical axis magnetic flux φ, /φ6 in the above embodiment, and this value is reduced below a predetermined reference level. It is possible to predict step-out in the same way as in the above embodiment by detecting that the direct-axis magnetic flux φ is reduced below a predetermined reference level (see section A in FIG. 3). (See part A in Figure 3) or the horizontal axis magnetic flux φ has decreased below a predetermined reference level (see part B in Figure 3). can be predicted.

As an alternative, the reduction rate of the direct axis magnetic flux φ6 (-d(1)d/D
t) increases above a predetermined reference level (see section A in Figure 3), or the rate of decrease of the horizontal axis magnetic flux φ9 (-dφ,
/Dt) increases above a predetermined reference level (Fig. 3゜“B
It is possible to predict the step-out in the same way as in the above-mentioned embodiment by detecting the occurrence of the problem (see section 1).

Furthermore, by detecting that the absolute values of the direct-axis magnetic flux φ6 and the horizontal-axis magnetic flux φ9 are both decreasing (see section ゜゜B゛ in Fig. 3), it is possible to predict step-out in the same manner as in the above-mentioned embodiment. .

Note that although the above-described embodiments were directed to synchronous generators, it goes without saying that the method of the present invention can be similarly applied to synchronous machines in general, such as synchronous motors and synchronous phase modifiers.

According to the method of the present invention, it is possible to accurately predict that the synchronous machine is in a dangerous state where there is a risk of step-out, and this has an extremely large effect in contributing to improving the synchronous machine control function.

Furthermore, the method of the present invention can be applied to detecting changes in the state of a synchronous machine other than step-out.

Although the preferred embodiments of the present invention have been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the operation of a conventional out-of-step detection method for a synchronous machine, Fig. 2 is an explanatory diagram showing the operation of a conventional out-of-step measurement method for a synchronous machine, and Fig. 3 is an explanatory diagram showing the operation of a conventional out-of-step detection method for a synchronous machine. A graph showing changes in the vertical axis magnetic flux and the horizontal axis magnetic flux of the air gap,
FIG. 4 is a block connection diagram showing the configuration of a synchronous generator control circuit using the synchronous machine detuning measurement method according to the present invention. 10...Synchronous generator, 10a...Field winding, 12.
... Impedance, 14... Power system, 16...
Voltage deviation detector, 18... Voltage transformer, 20... Addition calculator, 22... Excitation system auxiliary device, 24...
- Air gap magnetic flux detection device, 26... Direct axis/horizontal axis position detector, 28... Waveform analyzer, 30... Direct axis/horizontal axis magnetic flux analyzer, 32... Division calculator, 34. ... Signal level comparator, 36 ... Amplifier, 38 ... De-tuning measuring device, 4
0... Automatic voltage regulator, 42... Excitation device.

Claims (1)

[Claims] 1 Detecting the direct axis magnetic flux and the horizontal axis magnetic flux in the air gap in the synchronous machine, and detecting that at least one of the direct axis magnetic flux and the horizontal axis magnetic flux has decreased below a predetermined reference level, or that at least the direct axis magnetic flux and the horizontal axis magnetic flux have decreased to below a predetermined reference level. It is possible to predict a step-out by detecting that the operating point of the synchronous machine given by the direct axis magnetic flux and the horizontal axis magnetic flux is out of a predetermined range due to an increase in one of the reduction rates above a predetermined reference level. Features a step-out prediction method for synchronous machines.