JP3174525B2 - Modeling method, prediction method, and system stabilization control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a modeling method, a prediction method, and a system stabilization control method for stabilizing a power system.

[0002]

2. Description of the Related Art A system stabilization method is a method for stabilizing a fluctuation phenomenon of a generator. For example, in a power plant having a group of pumped generators, when an accident occurs in this system, the pumped generator is disconnected. It is used to shut down the required number of generators to minimize the tuning phenomenon and stabilize the entire system. FIG. 20 is a conceptual diagram of a system showing an example of a conventional system stabilization control device. In this figure, reference numeral 1 denotes a generator of a power plant (hereinafter referred to as a self-end) in which a system stabilization control device is installed, 2 denotes a main system constituted by a multi-machine system including a representative generator other than the self-end, Reference numeral 3 denotes a main generator on the main system side used in system stabilization (hereinafter referred to as a representative generator), 4 denotes a system stabilization control device, 5 denotes a data measurement point at the own end used by the system stabilization control device 4, and 6 denotes Reference numeral 7 denotes a data measurement device of the representative generator, and denotes a transmission path for transferring data from the data measurement device 6 installed in the representative generator 3 to the system stabilization control device 4.

In the conventional system stabilization control device 4, the input of the system state to the device is measurement data at the own end and representative points on the main system side. Here, as a representative point on the main system side, it is necessary to select a generator that is likely to be shaken relative to its own end in the event of a system accident based on a system phenomena analysis in advance. Also, in order to use the data of the representative point at its own end, it is necessary to set up a dedicated transmission path.

FIG. 19 is a schematic diagram of the online modeling of an equivalent generator described in “Basic study on system stabilization control method based on prediction arithmetic logic” presented at the 1996 IEEJ Power and Energy Division Conference. is there. In FIG. 19, reference numeral 1 denotes a generator which is subjected to online modeling and is subjected to a prediction operation, 2 denotes a main system other than its own end, 5 denotes a measurement point for measuring data for performing online modeling, and 8 denotes a main system. The virtual counterpart end 9 reduced in the one-generator model indicates the line reactance virtually existing between the own end and the virtual counterpart end.

Next, the operation of this conventional example will be described.
In the above "Basic study on system stabilization control method",
As shown in FIG. 19, the present system other than the own end is simulated by an equivalent one-generator (hereinafter referred to as the other end), and two generators, the own end and the virtual opposite end, are considered, so that the other end is assumed in advance. An online modeling logic has been reported for grasping the sway phenomenon using information obtained after an accident at the end without making a selection.

In FIG. 19, information measurable after the accident at the self end (1) is a tidal current value (P1) at a measurement point near the self end.
+ JQ1) and the voltage value (V1) at the measurement point. At this time,

(Equation 1) as well as

(Equation 2) Holds. By solving this equation for XL,

(Equation 3) Is obtained. Here, if the voltage value (E2) of the virtual partner end is not changed greatly in the transient region immediately after the accident, the line reactance (XL) between the self-end and the virtual partner end can be set by setting in advance. It can be calculated from Equation 3. By substituting the obtained XL in Expression 2 again, the phase difference between the self end and the virtual counter end becomes

(Equation 4) Can be calculated as

However, actually, even in the transient region of the fluctuation phenomenon after the accident, the voltage value (E2) at the other end may fluctuate to some extent, and the voltage value set in advance may be different. There is a problem that the phase angle calculated by Expression 4 is not always calculated accurately due to the nature of the phase angle. In addition, although Expression 3 includes the operator "±", there is a problem that there is no specific method for selecting one of them.

In the above-mentioned literature relating to the prediction operation logic, the generator constant (inertia constant: M2, damping coefficient: D2) and the generator mechanical input (PM2) of the counterpart generator are as follows.

(Equation 5) Can be expressed by the equation of motion for the virtual counter-end generator represented by Here, n time sections (t1,..., T
In n), by using the time-series data of the phase angle (θ2) obtained from the above equation 4,

(Equation 6)

(Equation 7) By applying the least squares method to the formula

(Equation 8) From the inertia constant (M2) and damping coefficient (D
2) and that the generator mechanical input (PM2) can be calculated.

However, compared to the fluctuation of the phase angle of the self-end, it can be said that the amplitude of the fluctuation of the virtual counterpart which generally represents the present system is small. For this reason, the value of the second derivative of the phase angle required when calculating Equation 7 includes many errors, and there is a problem in the calculation accuracy of the generator constant.

[0010]

Since the modeling method based on the online measurement data of the virtual counterpart with respect to the self-end used in the conventional stabilization method is configured as described above, the calculation of the phase angle of the virtual counterpart is performed. In addition, the calculation of the generator constant of the virtual generator has a problem that the calculation accuracy is not satisfied.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is intended for calculating a virtual counter-end phase angle and calculating a generator constant using only self-end information.
It is intended to improve the calculation accuracy. Another object of the present invention is to perform advance prediction calculation when it is predicted from the phase angle and the generator constant calculated only from the self-end information that the generator will lose synchronism after the occurrence of an accident and diverge. And calculating the number of generator shutoffs required for the stabilization control.

Still another object of the present invention is to provide a modeling method capable of improving the accuracy of the phase angle calculation in the calculation of the phase angle between the self-end and the virtual counter end irrespective of the preset value of the voltage of the virtual counter end. To provide.

Still another object of the present invention is to calculate the generator constant after calculating the phase angle between the self-end and the virtual counter end, even if the fluctuation deviation of the virtual counter-end phase angle is small. An object of the present invention is to provide a modeling method capable of improving accuracy.

Still another object of the present invention is to provide a prediction method for performing a prediction calculation of a vibration phenomenon after a system fault occurs after calculating a generator phase angle and a generator constant.

Still another object of the present invention is to provide a prediction method for judging whether or not the generator will step out if the current state is maintained, using the result of the prediction calculation of the fluctuation phenomenon of the generator. Is to do.

Still another object of the present invention is to provide a system stabilization control method for shutting down a generator necessary for stabilizing the system when it is predicted that the generator will step out after a system failure occurs. To provide.

[0017]

According to the first aspect of the present invention, there is provided a modeling method for removing an error due to a pre-set value of a virtual counter terminal voltage before calculating a line reactance between the own terminal and the virtual counter terminal. The phase angle is calculated vectorwise assuming that the other end voltage does not change, and the line between the own end and the virtual opposite end is vectorized using the voltage value when the phase angle is detected to be the largest. After the reactance is calculated and the line reactance is calculated, the phase angle between the own end and the virtual counterpart end is calculated in vector using the line reactance.

According to a second aspect of the present invention, in order to eliminate a calculation error generated for fixing the virtual counter terminal voltage to a pre-set value, a vector calculation is performed from the current counter terminal voltage value. And the phase angle calculated vectorially from the line reactance. If the difference is larger than a certain value, the virtual terminal voltage value and the line reactance are corrected so as to reduce the difference. The phase angle between the mating ends is calculated.

In the modeling method according to the third aspect of the present invention, when calculating the generator constant, the two generator models of the self-end and the virtual counter end are not separately treated, and the one-generator generation equivalent in stability is obtained. By replacing it with a machine model, the generator constant required for the prediction calculation of the oscillation phenomenon is calculated without calculating the generator constant of the virtual counterpart having a small phase angle variation.

According to a fourth aspect of the present invention, in the calculation of the generator constant, when the equation of motion of the generator is calculated from the time series data of the measured data by using the least square method, the equation of motion is calculated in advance. By removing the term of the second order derivative of the phase angle by performing indefinite integration, the calculation error is reduced and the generator constant is calculated.

According to a fifth aspect of the present invention, there is provided a prediction method comprising:
Instead of calculating the network equation of the generator and the infinite bus system used for the prediction calculation from the line reactance and the virtual counterpart voltage value calculated by the phase angle calculation method, the phase angle calculated by the phase angle calculation method described above. Based on the fact that the relationship between the phase angle and the electrical output can be expressed by a trigonometric function using the time-series data of the electrical output value that can be measured at its own end, the circuit equation is calculated using a trigonometric function based on the mathematical expression. In addition, the motion equation and the network equation expressing the fluctuation of the generator are alternately solved to perform the prediction calculation of the fluctuation phenomenon.

According to a sixth aspect of the present invention, there is provided a prediction method comprising:
In calculating the network equation based on the phase angle and the electrical output in the above-described prediction method, the past time series data is selected so that the phase interval becomes uniform, and the network equation is corrected to predict the fluctuation phenomenon. The operation is performed.

According to a seventh aspect of the present invention, there is provided a prediction method comprising:
The self-end generator and the virtual counter-end generator are equivalent in stability 1
Prediction of generator sway when shutdown is performed by calculating the change in equivalent generator constant when the self-end generator is shut down when performing the prediction calculation by replacing with the generator / generator model The operation is performed.

[0024] The prediction method according to the invention described in claim 8 is as follows.
As a result of performing the prediction calculation of the phase angle and the electric output of the generator using the prediction calculation method of the generator sway, when the phase angle of the generator is increased and the electric output value of the generator is decreased, an accident occurs. By lowering the generator output value before the occurrence,
The step-out phenomenon of the generator is determined before the actual step-out phenomenon occurs.

In the system stabilization control method according to the ninth aspect of the present invention, the out-of-step phenomenon of the generator is predicted in advance of the actual out-of-step phenomenon by using the method of predicting and determining out-of-step of the generator. In this case, by shutting down a predetermined number of generators among a plurality of generators, the out-of-step phenomenon of the remaining generators is suppressed and the system is stabilized.

According to a tenth aspect of the present invention, in the system stabilization control method, when the out-of-step is predicted by the method for predicting and determining the out-of-step of the generator, the number of cut-offs of the generator is sequentially changed. The prediction calculation of the generator sway is performed again using the prediction calculation method according to claim 7, and the above is repeated until it is predicted that the step-out phenomenon will not occur, thereby calculating the number of generator shutoffs required for stabilization. Is performed.

A system stabilization control method according to the invention according to claim 11, wherein the step-out phenomenon of the generator is predicted in advance of the actual step-out phenomenon using the method for predicting and determining step-out of the generator. One of the plurality of generators is shut off, and after waiting for a point in time when the phase angle becomes the minimum, one more
This is done by additionally blocking the table.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 2 is a flowchart showing the operation principle of the phase angle calculation method in the modeling method according to the first embodiment. FIG. 3 shows the first embodiment.
FIG. 6 is a diagram showing a vector-like relationship of various quantities in FIG.

Next, the operation of the first embodiment will be described with reference to FIG. In this method, first, step S1
In the above, first, the virtual partner terminal voltage (E2) is given as a set value. The following loop is repeatedly executed upon detecting that an accident has occurred on the system side.

In step S2, the voltage value (V1) at the measurement point of the power plant where the system stabilizer is installed is measured,
In step S3, the current value (P + jQ) is measured. In step S4, the absolute value of the current (I) and the phase angle (α) with respect to the voltage at the measurement point are determined using the measured data.

(Equation 9) Is calculated as Note that it is also possible to directly measure and use the current value in step S4.

In step S5, the line reactance (X
It is determined whether or not L) has already been calculated. That is,
When entering step S5 for the first time, it has not been calculated.
If the calculation has been completed, step S6 is performed. If the calculation has not been performed, step S7 is performed.

In step S6, the voltage value (V
1) Using the line reactance (XL), the current value (I), and the phase angle (α) of the current, the phase angle (β) of the virtual counterpart with respect to the current is calculated by the following equation.

(Equation 10)

In step S7, the voltage value (V
1) Using the voltage value (E2) of the virtual partner end and the phase angle (α) of the current, the phase angle (β) of the virtual partner end with respect to the current is calculated by the following equation.

[Equation 11]

In step S8, the maximum value is determined using, for example, the differential value of the phase angle (β). In this step S8, the maximum value of the current value (I) can be used instead of β. If the value is the maximum value, the process proceeds to step S9. If the value is not the maximum value, step S10 is performed.

In step S9, the voltage value (V
1), using the voltage value (E2) of the virtual partner end, the current value (I), the phase angle (α) of the current, and the phase angle (β) of the virtual partner end with respect to the current, the line reactance (XL) by the following equation:
Is calculated.

(Equation 12)

In step S10, using the phase angle (α) of the current with respect to the measurement point and the phase angle (β) of the virtual counterpart with respect to the current, the phase angle (δ) of the virtual counterpart with respect to the measurement point is calculated by the following equation. Perform

(Equation 13) When the calculation of the phase angle (δ) is completed, the process returns to step S2 for performing the next measurement.

Embodiment 2 FIG. 4 is a flowchart showing the operation principle of the phase angle calculation method in the modeling method according to the second embodiment of the present invention.

Next, the operation of the second embodiment will be described with reference to FIG. The second embodiment is a part for initializing E2. Steps S1 to S5 are the same as those in the first embodiment.

In step S20, the phase angle is calculated in the same manner as in step S6 of the first embodiment, but the value obtained here is β1.

In step S21, the phase angle is calculated in the same manner as in step S7 in the first embodiment, but the value obtained here is β2. Accordingly, the phase angle used in steps S22 and S23 corresponding to steps S7 and S8 in FIG.
Replace with 2.

In step S24, the phase angle (δ) between the self end and the virtual partner end is calculated by the following equation.

[Equation 14]

In step S25, the calculated phase angle β
For 1 and β2, it is determined whether or not the maximum value Max (larger one) of β1 / β2 and β2 / β1 is larger than a predetermined constant K, and if Max ≦ K, the next data is measured. Therefore, the process returns to step S2. If Max> K, the process proceeds to step S26, where α, β1, β2, V1
Modify E2 using.

In step S26, the voltage value at the virtual partner end is corrected by the following equation.

(Equation 15) Note that K shown in the flowchart is a pre-setting item,
It is a constant value of about 1 or 2. After the correction of the virtual counter terminal voltage is completed, step S2 is performed to measure the next data.
Return to

Embodiment 3 FIG. FIG. 5 is a conceptual diagram of a generator constant calculation method in the modeling method according to the third embodiment.

Next, the operation principle of the third embodiment will be described with reference to FIG. Generally, the two-generator system can be considered by replacing it with a one-generator-infinite bus system equivalent in stability. At this time, the equation of motion of the equivalent single-generator model is expressed by the following equation.

(Equation 16)

The relationship between the generator constant and the like of the two-machine model and the one-machine equivalent model is as follows.

[Equation 17] It is. Here, regarding the line between the own end and the virtual counter end, since only the reactance is assumed in the above-described phase difference calculation method, there is no loss of active power, and the following equation holds.

(Equation 18) Therefore, Equation 16 is

[Equation 19] Can be rewritten as

By using this equation 19 instead of equation 5, if the time series data of the phase difference (δ) between the self end and the virtual counter end, which can be calculated by the phase angle calculation method of the first and second embodiments, is used, ,

(Equation 20)

(Equation 21) By applying the least squares method to the formula

(Equation 22) As a result, it is possible to calculate the generator constant of the equivalent single generator.

Embodiment 4 Embodiment 4 of the present invention realizes the operation principle of the generator constant calculation method in the modeling method according to the present invention. Indefinite integration is performed on the equation of motion of the equivalent one-generator model of Equation 19,

(Equation 23) And transform. Here, C is an integral coefficient accompanying indefinite integration.

Regarding the phase angle (δ), if n time slice data (t1,..., Tn) are obtained by using the phase angle calculation method of the first and second embodiments, for example,
The following equation is obtained by an equation modification similar to equation 21.

(Equation 24) Here, T is a data sampling interval. Therefore,

(Equation 25) The generator constant of the equivalent generator can be calculated.

Embodiment 5 FIG. 6 is a flowchart in the prediction calculation method according to the fifth embodiment of the present invention. FIG. 7 is a conceptual diagram of power phase difference characteristic correction used in this prediction calculation method.

Next, the operating principle of the fifth embodiment will be described with reference to FIG. When a prediction operation of the operation of the generator is performed, for example, a network equation representing the power phase difference characteristic of the two generators represented by the following equation (step S84)
And the generator equation of motion (step S85) is alternately solved.

(Equation 26)

[Equation 27] Therefore, as shown in the flowchart of FIG.
Using the values of the phase angle and the electric output obtained by performing the measurement of the self-end information (step S80) and the online modeling (step S81), it is possible to execute the prediction calculation by alternately solving the above equations. (Step S
83 to step S86).

The power phase difference characteristic at this time is, as shown in Expression 26, the own end voltage value (E1) and the other end voltage value (E2).
It can be calculated if the line reactance (XL) between itself and the other end is known. Therefore, the characteristics of Equation 26 are identified by using the online measurement data by converting the own end and the main system corresponding thereto to a one-machine-infinite bus system model using the method of the above-described first to fourth embodiments. It is possible.

However, an error may occur due to a difference between the actual system and the model system. In such a case, Equation 2
6 is more generally replaced by the following equation (step S8)
2).

[Equation 28] Therefore, using the on-line measured PE (t) and the time series data of δ (t) calculated by the phase angle calculation method at regular time intervals, the equation 28 is modified as follows to obtain each coefficient.

(Equation 29)

[Equation 30]

If b1, b2, and P0 are calculated by applying the least squares method, P1 and θ0 can be calculated by the following equations.

(Equation 31)

(Equation 32)

By performing the prediction calculation of the one-generator-infinite bus system using the power phase difference characteristic corrected by this method, it is possible to improve the prediction calculation accuracy.

Embodiment 6 FIG. FIGS. 8A and 8B show the effect of improving the correction by the power phase characteristic correction of the prediction operation method according to the sixth embodiment of the present invention, wherein FIG. 8A shows the effect of the present invention, and FIG. 8B shows the effect of the conventional method.

Next, the operation of the sixth embodiment will be described. In the correction method according to the fifth embodiment, the time series data of the electric output (PE) and the phase angle (δ) used for the correction are selected from the current time at a fixed time interval while going back in the past and used for the calculation.

On the other hand, the power phase difference characteristic correction method according to the sixth embodiment focuses on the phase angle when selecting data while going back in time from the current time to the past. Is selected which satisfies the condition that the angle exceeds a predetermined angle. By repeating this operation, when selecting past time series data,
On the plane of the power phase difference, as shown in FIG. 8A, the selected time-series data is selected at equal intervals,
It is possible to improve the calculation accuracy when calculating the power phase difference characteristic by the least square method.

By using the power phase difference characteristic corrected by this method to perform the prediction calculation of the one-generator-infinite bus system, it is possible to improve the prediction calculation accuracy.

Embodiment 7 FIG. (A) of FIG. 9 is a flowchart of a prediction calculation method (method 1) when the generator is shut off when the prediction calculation method according to the seventh embodiment of the present invention is used. FIG. 9B is a flowchart of another prediction calculation method (method 2) when the generator is shut down when this prediction calculation method is used.

Next, the operating principle of the seventh embodiment will be described with reference to FIG. First, method 1 will be described.

Based on the data measurement at its own end in step S31, in step S32, a generator constant of an equivalent generator model that characterizes the oscillation phenomenon after the accident is calculated using the above-described modeling method or the like.

In step S33, the number of shutoffs of the self-end generator is set.

In step S34, the inertia constant (M
Using the inertia constant (M) of the equivalent generator calculated in 1) and step S32, the inertia constant (M2) of the virtual counter-end generator is calculated by the following equation.

[Equation 33]

In step S35, a change in the inertia constant of the self-end generator is calculated using the number of cutoffs selected in step S33. That is, when the total number of generators is N and the number of generators to be cut off is n, the cutoff coefficient (a =
(N−n / N)), the inertia constant (M′1) of the self-end generator after the cutoff is performed is expressed by the following equation.

(Equation 34) Is represented by

In step S36, using the M2 calculated in step S34 and the M'1 calculated in step S35, the inertia constant (M ') of the equivalent generator after the cutoff is calculated by the following equation.

(Equation 35)

In step S37, a prediction calculation is performed by using the above-described prediction calculation method or the like, using the inertia constant of the equivalent generator after the cutoff calculated in step S36.

Next, method 2 will be described. In method 2, the inertia constant of the equivalent generator of method 1 is calculated (step S
34, S35, and S36) are simplified from step S38. By this simplification, the step S of the scheme 2 is performed.
In 38, the following expression is used instead of Expression 35 in Step S36 of Method 1.

[Equation 36]

By this simplification, M ′ calculated using the method 1 includes an error when compared with M ′ calculated using the method 2, but in general, the inertia constant ( Inertia constant (M2) of virtual counter-end generator compared to M1)
Is about 10 times larger, the effect of the error is small.

Embodiment 8 FIG. FIG. 10 is a flowchart illustrating the operation principle of the step-out prediction determination method according to the eighth embodiment of the present invention. Next, the operation of the eighth embodiment will be described with reference to FIG.

In this method, in step S41, the electric output value of the self-end generator before the occurrence of the accident is stored.

In step S42, the above-described fifth embodiment is used.
And 6, the prediction calculation of the generator fluctuation phenomenon is performed for one sample step.

In step S43, the electric output of the equivalent generator obtained in step S42 is compared with the electric output of the previous prediction operation to determine whether the electric output has decreased. If so,
Since the step-out phenomenon does not occur, the process returns to step S42 to perform a prediction calculation at the next time. If it has decreased, there is a possibility of step-out, so the process proceeds to step S44.

In step S44, it is determined whether or not the equivalent generator electric output value currently predicted and calculated is smaller than the actual electric output of the self-end generator stored in advance. If it is large, the step-out phenomenon does not occur, and the process returns to step S42 to perform the prediction calculation of the next time. If small,
Since there is a possibility of step-out, the process proceeds to step S45.

In step S45, it is determined whether or not the phase angle has increased by comparing the result of the previous calculation with the phase angle. If it has decreased, no step-out phenomenon occurs, so the process returns to step S42 to perform a prediction calculation at the next time. If it has increased, it is determined that the step-out occurs.

Embodiment 9 FIG. 1 is a diagram illustrating a system having a system stabilization control device 4A incorporating a stabilization control method according to a ninth embodiment of the present invention. FIG. 11 is a flowchart showing the operation principle of the stabilization control method according to the ninth embodiment. The schematic configuration of the system in FIG. 1 is substantially the same as that of the above-described conventional example shown in FIG. 19 except for the system stabilization control device 4A.
The same reference numerals as in 9 are used.

Next, the operation principle of the ninth embodiment will be described with reference to the flowchart of FIG. In step S51, self-end information such as a power value, a current value, and a voltage value is measured. In step S52, the first to fourth embodiments
The phase angle and the generator constant are calculated for the equivalent generator model that characterizes the swaying phenomenon after the accident by using such a method.

In step S53, the fifth and sixth embodiments are used.
By using a prediction calculation method such as that described above, a prediction calculation of a fluctuation phenomenon of the generator ahead of the current state is performed.

In step S54, a determination is made as to whether or not the current operating state of the generator will step out in the future using the out-of-step prediction determination method of the eighth embodiment or the like. If it is not determined that the step-out occurs, the process returns to the measurement of the self-end information in step S51. If it is predicted that the step-out will occur, the process proceeds to step S55.

In step S55, a preset number of generators is selected from a plurality of self-terminal generator groups.

In step S56, the generator selected in step S55 is actually cut off.

Embodiment 10 FIG. FIG. 12 is a flowchart showing the operation principle of the stabilization control method according to the tenth embodiment of the present invention.

The operation principle of the tenth embodiment will be described with reference to FIG. Steps S51 to S54 are the same as in the ninth embodiment.

In step S57, the number of generators to be cut off is increased by one. When this process is performed for the first time, one device is selected.

In step S58, a prediction calculation is performed in the case where the number of generators selected in step S57 is cut off, using the method of the seventh embodiment or the like.

In step S59, it is determined using the out-of-step prediction determination method of the eighth embodiment or the like whether or not the fluctuation phenomenon of the generator calculated in step S58 is out of step. If it is not determined that the step-out occurs, step S
Proceed to 60. If step-out is predicted, the process returns to step S57.

In step S60, the number of generators to be cut off selected in step S57 is selected from a plurality of own-end generators, and the cutoff is actually performed.

The application result of this method using a simple two-machine system model system will be described. FIG. 13 shows the configuration of a two-machine system model used for verification. In the figure, G1 is a power station at its own end where a system stabilization control device based on the equal stabilization control method is installed, and G2
Is the power station on the other end.

FIG. 14 shows the result of performing the generator phase angle calculation according to the method described in the second embodiment using the self-end information at the data measurement point (GEN1) of the self-end power plant G1 in this system. Show. From FIG. 14, it can be confirmed that the two values are exactly the same and that the phase angle between the own end and the other end can be calculated from only the own end information.

FIG. 15 shows a generator constant calculation result of an equivalent generator using the generator constant calculation method shown in the fourth embodiment.
Shown in In FIG. 15, it can be seen that the true value indicated by the solid line and the predicted value indicated by the broken line substantially match.

The self-power station G1 of the two-machine system model is
FIG. 17 shows a prediction calculation result accompanying the calculation of the control amount in the case where four generators are provided and each of them can be cut off one by one. In FIG. 17, the number of generators shut off is shown in parentheses. From FIG. 17, when the shut-off is not performed, the electric output (PE) of the generator continues to decrease, leading to step-out. However, by shutting down one unit, the step-out phenomenon can be prevented beforehand. Obtained from the prediction operation results. Note that the number of cutoff units coincided with the result of selecting the number of cutoff units by trial and error using a detailed generator stability analysis program.

Embodiment 11 FIG. FIG. 18 is a flowchart showing the operation principle of the stabilization control method according to the eleventh embodiment of the present invention.

Next, the operation principle of the eleventh embodiment will be described with reference to FIG. In step S71, self-end information such as a power value, a current value, and a voltage value is measured.

In step S72, the phase angle and the generator constant are calculated for the equivalent generator model that characterizes the post-accident sway phenomenon using the techniques of the first to fourth embodiments.

In step S73, it is determined whether the value of the phase angle calculated in step 2 is a minimum value, and whether the additional cutoff flag is set to true. Note that when entering step S73 for the first time, the additional cutoff flag is set to false. If applicable (true), step S77
If not, the process proceeds to step S74.

In step S74, a prediction calculation of the fluctuation phenomenon of the generator ahead of the current state is performed using the prediction calculation method of the fifth and sixth embodiments.

In step S75, a determination is made as to whether or not the current operating state of the generator will step out in the future, using the out-of-step prediction determination method of the eighth embodiment or the like. If it is not determined that the step-out occurs, the process returns to the measurement of the self-end information in step S71. If step-out is predicted, step S75
Proceed to.

In step S76, the additional cutoff flag is set to false.

In step S77, the additional cutoff flag is set to true.

In step S78, a preset number of generators is selected from a plurality of self-terminal generator groups.

In step S79, the selected generator is actually cut off.

[0102]

As described above, according to the first or second aspect of the present invention, with respect to the phase angle calculation method between the self-end and the virtual counter end, regardless of the pre-set value of the virtual counter-end voltage, Based on the self-end information measured during the oscillation of the system, the line reactance between the self-end and the virtual mating end is calculated, and then the phase angle between the self-end and the virtual mating end is calculated. Therefore, even if the voltage at the other end or the line reactance changes during the phenomenon, the phase angle can be calculated correctly.

According to the third aspect of the present invention, since the self-end and the virtual counter-end generators are combined into an equivalent generator to calculate the generator constant, the generator constant of the virtual counter-end is likely to be low in calculation accuracy. Without performing the calculation, the characteristic of the equivalent single-generator that characterizes the fluctuation phenomenon can be identified.

According to the fourth aspect of the invention, when solving the equation of motion of the equivalent generator, the term of the second derivative of the phase angle, which is likely to cause an error, is deleted by performing indefinite integration in advance on the mathematical expression. Therefore, there is an effect that the calculation of the generator constant is hardly affected by a calculation error.

According to the fifth or sixth aspect of the present invention, the relationship between the electrical output of the equivalent generator and the phase angle is corrected using actual measurement data. This has the effect of reducing the error.

According to the seventh aspect of the present invention, when performing the prediction calculation of the swaying phenomenon, the generator constant is calculated when the generator is shut off, so that the swaying phenomenon after the execution of the shutoff is performed. Has the effect that the prediction calculation of

According to the eighth aspect of the present invention, it is possible to determine whether or not the generator shakes using the result of the prediction calculation of the fluctuation phenomenon of the generator.

According to the ninth, tenth, or eleventh aspect of the present invention, when the generator loses synchronism by using the prediction calculation result of the fluctuation phenomenon of the generator, the loss of synchronism is prevented beforehand. Therefore, there is an effect that the system can be stabilized by shutting off the generator necessary for the system.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a system stabilization device using a stabilization control method according to a ninth embodiment of the present invention.

FIG. 2 is a flowchart illustrating a phase angle calculation method according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between phase angles in a phase angle calculation method according to the first embodiment of the present invention.

FIG. 4 is a flowchart illustrating an operation of a phase angle calculation method according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating reduction by an equivalent generator in a generator constant calculation method according to a third embodiment of the present invention.

FIG. 6 is a flowchart illustrating an operation of a prediction calculation method according to Embodiments 5 and 6 of the present invention.

FIG. 7 is an explanatory diagram of a power phase difference characteristic correction method in a prediction calculation method according to a fifth embodiment of the present invention.

FIG. 8 is an example of a correction result by a power phase difference characteristic correction method in a prediction calculation method according to a sixth embodiment of the present invention.

FIG. 9 is a flowchart illustrating an operation of a prediction calculation method according to a seventh embodiment of the present invention.

FIG. 10 is a flowchart illustrating an operation of a step-out prediction determination method according to an eighth embodiment of the present invention.

FIG. 11 is a flowchart illustrating an operation of a control amount calculation method according to a ninth embodiment of the present invention.

FIG. 12 is a flowchart illustrating an operation of a control amount calculation method according to a tenth embodiment of the present invention.

FIG. 13 shows a model system verified in the tenth embodiment of the present invention.

FIG. 14 shows verification results of a phase angle difference calculation method according to the tenth embodiment of the present invention.

FIG. 15 shows verification results of a generator constant calculation method according to the tenth embodiment of the present invention.

FIG. 16 is a diagram illustrating a prediction calculation result of a generator output value according to the tenth embodiment of the present invention.

FIG. 17 shows a cutoff amount calculation result according to the tenth embodiment of the present invention.

FIG. 18 is a flowchart illustrating an operation of a control amount calculation method according to Embodiment 11 of the present invention.

FIG. 19 is an explanatory diagram of a stabilization control method based on self-end information published so far.

FIG. 20 is a conceptual diagram of a system showing an example of a conventional system stabilization control device.

[Explanation of symbols]

1 The generator at the power station where the stabilizer is installed, 2
This system is composed of a multi-machine system including a representative generator at a position other than its own end. 3 A representative generator (representative generator) on the main system used for conventional system stabilization; 4, 4A system stabilization control device;
Data measurement point at own end, 6 Data measurement device of representative generator on main system side used for system stabilization, 7 Transmission for data transfer from data measurement device installed at representative generator to system stabilization device Road, eight virtual systems reduced by a single-generator model, virtual counter-end, 9 track reactance virtually existing between the self-end and virtual counter-end.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideharu Oshida 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Shinichi Imai 1-3-1, Uchisaiwaicho, Chiyoda-ku, Tokyo TEPCO Inside (72) Inventor Toshiya Shoji 1-3-1 Uchisaiwai-cho, Chiyoda-ku, Tokyo Inside Tokyo Electric Power Company (56) References JP-A-8-126205 (JP, A) JP-A-6-351163 (JP) , A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02J 3/00 G06F 17/00 G06F 19/00 H02J 3/24

Claims (11)

(57) [Claims] 1. A power plant having a group of pumped generators,
While the generator is shaking due to the occurrence of an accident in this system, while measuring information that can be measured at the own end, the shaking phenomenon between the own end and the main system using the self-end and virtual counterpart models that characterize the shaking phenomenon local end voltage for simulating the - virtual remote end collector
A method for calculating the phase angle between the pressure in the transition region of the upset phenomenon, assume that the voltage of the virtual remote end does not change, the phase with respect to the host terminal voltage measurable amount of current and the current at local end with corner, a step of calculating a phase angle with respect to the host terminal voltage of the virtual remote end voltage from the vector diagram, when the phase angle during each upset cycle is maximized, local end using a current amount of the time A step of calculating the reactance between the virtual counterpart terminals, and after the reactance calculation, the amount of current measurable at the own end and the phase angle of the current with respect to the self-end voltage are used to calculate the virtual counter-end voltage based on the vector diagram. Calculating a phase angle with respect to the terminal voltage . 2. The modeling method according to claim 1, wherein a virtual counter-end phase angle obtained by using the calculated line reactance, a current value measured at the self-end, and a phase angle of the current with respect to the self-end voltage ; The value of the virtual partner terminal voltage set in advance as the value, the current value measured at the own terminal, and the own terminal of the current
Self-end of virtual counterpart obtained using phase angle with respect to voltage
Comparing the phase angle with respect to the voltage to determine the phase angle difference between them, and when the phase angle difference is larger than a preset value, set the line reactance and the set value of the virtual counter-end voltage value. Correcting the phase angle difference so as to reduce the phase angle difference. 3. The modeling method according to claim 1, wherein the self-end voltage of the virtual counter-end voltage calculated from the vector diagram is
The time-series data of the virtual remote end generator output calculated from the measured values of the electric output of the absolute phase angle and Zidane generator virtual remote end voltage obtained from the phase angle by subtracting the absolute phase angle of the host terminal voltage against , the inertia constants of more virtual remote end generator method of least squares fit to the equation of motion of the virtual remote end generator, further comprising the step of calculating the value of the damping coefficient and mechanical input, the inertia of the virtual remote end generator In the step of calculating the values of the constant, the damping coefficient, and the mechanical input, the self-end-virtual counter end generator is replaced by a one-generator-infinite bus model equivalent in stability to the self-end-virtual counter end. Apply the time series data of the calculated value of the phase angle between and the measured value of the electrical output of the own-end generator to the equation of motion of the equivalent generator, and apply the inertia constant, damping coefficient and mechanical Modelin to calculate the value of a statistical input Method. 4. The modeling method according to claim 3, wherein, instead of the measured value of the electric output of the self-end generator, an integral value of the measured value of the electric output is mathematically indefinitely integrated with the equation of motion of the generator. Modeling method was by fitting the equation to calculate more generator inertia constants, the value of the damping coefficient and mechanical input to the least squares method. 5. A phase angle, a phase angular velocity and a line reactance obtained by the modeling method according to claim 1 or 2,
Using a generator generator constants obtained by modeling method according to claim 3 or 4, the state of the phase angle and electrical output of the previous generator from the present time, by solving the equation of motion and the network equations alternately In the prediction method of performing the prediction calculation, the electric power and the phase angle of the generator that can be measured at the own end are calculated.
Prediction method using the time-series data of more resulting phase angle law, performs predictive operation on the network equations makes a correction based on the assumption that can be represented by a trigonometric function. 6. The prediction method according to claim 5, wherein the electric power of the generator which can be measured at its own end and the time series data of the phase angle obtained by the phase angle calculation method are used.
A prediction method in which, when correcting a network equation, a prediction operation is performed after correcting the network equation using the time series data selected so that the phase difference is constant with respect to the phase angle time series data used for the correction. . 7. The predicting method according to claim 5, wherein a step of calculating a generator constant and a power phase difference characteristic of the equivalent generator when the self-end generator is cut off; Performing a prediction calculation of a fluctuation phenomenon of the generator when the generator is cut off in the operation state of the above. 8. The prediction method according to claim 5, wherein the electric output value of the self-end generator before the occurrence of the system fault and the electric output value of the self-end generator after the occurrence of the system accident obtained by the prediction calculation And the predicted value of the phase angle value, the predicted value of the electric output value is lower than the electric output value before the accident or the value obtained by multiplying the electric output before the accident by a coefficient set in advance, and the predicted value of the phase angle A step of predicting that the generator will step out when is increasing. 9. A step of predicting whether or not the generator will step out after the occurrence of a system fault, using the prediction method of claim 8,
A step of shutting off a preset number of a plurality of self-end generators to prevent a step-out of the self-end generator beforehand, and a system stabilization control method comprising: 10. The system stabilization control method according to claim 9, wherein when it is predicted that the generator is out of synchronization by the generator out-of-synchronization prediction determination method, the out-of-synchronization is performed while increasing the number of shut-offs of the generator one by one. Calculating the number of generators required to prevent step-out by repeatedly applying the prediction method according to claim 7 until the prediction is no longer performed; A step of preventing out-of-step of the own-end generator by shutting down the number of the generators, further comprising: 11. The system stabilization control method according to claim 9, wherein when it is predicted that the generator will step out after a system accident occurs,
A step of shutting off a predetermined number of the plurality of self-end generators, and a time when the phase angle difference between the self-end and the virtual counterpart end becomes minimum after cutting off the predetermined number of the plurality of self-end generators A step of waiting for, and further adding a specified number of cutoffs to prevent step-out of the self-end generator beforehand.