CN104242245A - Method and device for generator out-of-step protection - Google Patents
Method and device for generator out-of-step protection Download PDFInfo
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Abstract
The invention provides a method and a device for generator out-of-step protection. The method comprises the steps of A, obtaining the total impedance of a generator to an infinite bus, B, determining the isostatic boundary circle of the impedance plane of the infinite bus according to the total impedance, C, converting the isostatic boundary circle into a isostatic boundary circle on the impedance plane of a generator terminal, D, measuring the impedance of the generator terminal, when the impedance of the generator terminal goes in from the right side of the isostatic boundary circle and out from the left side of the isostatic boundary circle in predetermined time, confirming out-of-step acceleration of the generator and performing out-of-step acceleration protection, and when the impedance of the generator terminal goes in from the left side of the isostatic boundary circle and out from the right side of the isostatic boundary circle in the predetermined time, confirming out-of-step deceleration of the generator and performing out-of-step deceleration protection. According to the method and the device for generator out-of-step protection, the out-of-step faults can be detected in the first period of oscillation and the power swing is excellent.
Description
Technical Field
The invention relates to the field of power system equipment, in particular to a power system fault diagnosis and processing technology.
Background
Generator sets are one of the important components of electrical power systems. With the development of large generating sets and ultrahigh voltage power systems, the number of generating sets is continuously increased, the single-machine capacity of the generating sets is rapidly increased, the large generating sets are connected with a transformer forming unit, once system oscillation occurs, an oscillation center is often positioned near the generator end, and the safety of a generator, a transformer and even the whole system can be endangered. On the other hand, the continuous occurrence of the oscillation current can overheat the stator of the large-scale turbonator, cause the mechanical damage to the end part, strain the large shaft and shorten the service life. Therefore, the generator step-out protection is necessary based on the objective requirement of the safety and stability of the power system.
There are a plurality of methods for detecting whether the generator in the power system is out of synchronization: the method for detecting the step-out by using the impedance track measured at the machine end usually uses a double impedance element or a triple impedance element, and the method distinguishes the step-out, synchronous oscillation and short-circuit fault according to the impedance change track, has the defects of complex setting, incomplete physical meaning of the impedance element in an action area during the setting, and longer action time of the step-out fault by calculating the times of a sliding pole; on the other hand, the splitting device for detecting the asynchronous operation state by using the periodic change of the current amplitude envelope line has a simple structure and is easy to realize, but the change of the operation mode needs to change a fixed value, otherwise, synchronous oscillation is difficult to avoid, and selectivity is difficult to obtain when the oscillation period is short. The method is based on the step-out prediction protection of transient stability calculation, the step-out protection is based on a stability criterion and a theory, and has certain limitation in practical application, such as the condition that the equal-area rule is not suitable for being damaged by static stability; the step-out protection based on synchronous phase Measurement is characterized in that a signal of a certain reference voltage in a remote place is synchronously transmitted to the local place through a channel and compared with a local voltage signal to judge and predict step-out, a Global Positioning System (GPS) well solves the sampling synchronization problem of Phasor Measurement of different places in an electric power system, but a Phasor Measurement Unit (PMU) of the GPS is expensive to manufactureThe method for judging the step-out of the power system comprises the steps of calculating the voltage of an oscillation center by using the voltage and the current collected at the installation position of the device, and distinguishing step-out oscillation, synchronous oscillation and short circuit according to the change rule of the voltage of the oscillation centerFault, etc. the method has simple principle and clear physical meaning, but within one oscillation periodMay be small, the criterion may be due toCannot be refused when the system is out of step and oscillates due to continuous change in each zone.
At present, the out-of-step protection criterion which is mostly used in China is an impedance type criterion. The traditional impedance type criteria mainly comprise a double-impedance element out-of-step protection criterion and a three-impedance element out-of-step protection criterion. The setting of the double-impedance element is complex, the lens characteristic is set according to the dynamic stability limiting angle, but the dynamic stability limiting angle has different values, the setting value has errors, and the misoperation can be caused. The three-impedance element is complex in setting, and the step-out fault is judged by calculating the number of slide poles, so that the quick action is poor.
Disclosure of Invention
In view of the above, the invention aims to provide a fast and effective generator step-out protection method, and the invention introduces the change rule of the oscillation center voltage into the impedance plane, and reflects the change rule near the zero crossing point of the oscillation center voltage on the impedance plane, thereby disclosing a new impedance type step-out protection method and a device based on the change rule of the oscillation center voltage.
In order to achieve the purpose, the invention adopts the following technical scheme.
A method of generator step-out protection, the method comprising the steps of:
A. acquiring the total impedance of the generator to an infinite bus;
B. determining an isobaric boundary circle of an impedance plane at an infinite bus according to the total impedance;
C. transforming the isobaric boundary circle to an isobaric boundary circle on an impedance plane at the machine end;
D. measuring the impedance of the machine end, determining the generator as accelerating step loss when the impedance of the machine end penetrates into the right side and penetrates out of the left side of an isobaric boundary circle on an impedance plane of the machine end within preset time, and executing the accelerating step loss protection; and when the impedance at the machine end penetrates into the left side and penetrates out of the right side of the isobaric boundary circle on the impedance plane at the machine end in a preset time, determining that the generator is decelerated and desynchronized, and executing deceleration and desynchronization protection.
Wherein, the step B of determining the isobaric boundary circle of the impedance plane at the infinite bus comprises the following steps:
the center of a circle is <math>
<mrow>
<mfrac>
<mrow>
<msub>
<mi>Z</mi>
<mi>Σ</mi>
</msub>
<mo>/</mo>
<mn>2</mn>
</mrow>
<mrow>
<msubsup>
<mi>k</mi>
<mi>m</mi>
<mn>2</mn>
</msubsup>
<mo>-</mo>
<mn>1</mn>
</mrow>
</mfrac>
<mo>,</mo>
</mrow>
</math> Radius of
Wherein ZΣThe total impedance of the generator to the infinite bus;
kma voltage that is the center of oscillation;
the difference between the impedance angle at the oscillation center and the impedance angle at the infinite bus;
in addition, k ismThe value is 0.2.
Wherein, the step C of transforming the isobaric boundary circle into the isobaric boundary circle on the impedance plane at the terminal is as follows:
at circular diameter displacement Xs+XtObtaining an isobaric boundary circle on an impedance plane at the terminal;
wherein XsReactance, X at bus of infinitetIs the transformer reactance.
When the generator is a non-salient pole machine, the acceleration step-out protection is to send an acceleration step-out signal to the non-salient pole machine and reduce the output of a prime motor.
Or when the generator is a non-salient pole machine, the deceleration and desynchronization protection is to send a deceleration and desynchronization signal to the non-salient pole machine and increase the output of a prime motor.
Or the generator is a salient pole machine, and correspondingly, the acceleration step-out protection and/or the deceleration step-out protection is the operation of a generator cutter.
And the predetermined time is 25ms to 50 ms.
In particular, the predetermined time is 40 ms.
A generator step-out protection device, the generator step-out protection device comprising:
the impedance obtaining unit is used for obtaining the total impedance from the generator to an infinite bus;
the isobaric boundary circle calculation unit is connected to the impedance acquisition unit and used for determining an isobaric boundary circle of an impedance plane at an infinite bus according to the total impedance;
the isobaric boundary circle transformation unit is connected to the isobaric boundary circle calculation unit and is used for transforming the isobaric boundary circle of the impedance plane at the infinite bus into the isobaric boundary circle on the impedance plane at the terminal;
a terminal impedance measuring unit for measuring terminal impedance;
the generator step-out judging unit is connected to the extreme impedance measuring unit and the isobaric boundary circle transforming unit, and determines that the generator is out of step in an acceleration mode when the machine-end impedance penetrates from the right side and penetrates out of the left side of the isobaric boundary circle on the impedance plane at the end in a preset time, and determines that the generator is out of step in a deceleration mode when the machine-end impedance penetrates from the left side and penetrates out of the right side of the isobaric boundary circle on the impedance plane at the end in the preset time;
and the step-out protection unit is connected to the generator and the step-out judgment unit of the generator and is used for executing acceleration step-out protection or deceleration step-out protection according to the step-out type.
By adopting the method and the device for protecting the generator from the step-out, the step-out fault can be detected in the first oscillation period, and measures can be taken quickly. The problems that the traditional impedance type step-out protection setting is complex and the quick action performance is poor are solved.
In addition, the generator step-out protection method and the generator step-out protection device are still realized on an impedance plane, so that the method and the device can be improved on the basis of the original device, have low cost and good compatibility, and have better practical engineering significance.
Drawings
Fig. 1 is an equivalent circuit diagram of a single machine versus infinite system.
Fig. 2 is a schematic diagram of the voltage change of the oscillation center during the step-out process of the generator.
Fig. 3 is a schematic diagram of isobaric boundary circles for different values of oscillation center voltage.
Fig. 4 is a schematic diagram of determining the step-out of the generator according to the embodiment of the present invention.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings.
Detailed exemplary embodiments are disclosed below. However, specific structural and functional details disclosed herein are merely for purposes of describing example embodiments.
It should be understood, however, that the intention is not to limit the invention to the particular exemplary embodiments disclosed, but to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure. Like reference numerals refer to like elements throughout the description of the figures.
It will also be understood that the term "and/or" as used herein includes any and all combinations of one or more of the associated listed items. It will be further understood that when an element or unit is referred to as being "connected" or "coupled" to another element or unit, it can be directly connected or coupled to the other element or unit or intervening elements or units may also be present. Moreover, other words used to describe the relationship between components or elements should be understood in the same manner (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.).
The characteristics of the physical quantities during the loss of synchronism of the generator are first described below. FIG. 1 is an equivalent circuit diagram of a single machine versus infinite system. When the generator and the system in fig. 1 lose synchronization, the power angle between the generator and the infinite system swings, and the voltage U at the oscillation centerocA continuous change will ensue, with zero crossing. The process is shown in the attached figure 2: the oscillation center voltage is discontinuously changed and has sudden change when short circuit fault and fault are cut off; in synchronous oscillation, the oscillation center voltage is continuously varied, but does not cross zero. However, there is a problem in discriminating the step-out fault using the oscillation center voltage: u in each oscillation periodocAre not necessarily equal in amplitude, and sometimes may be greatly different, so that even if an out-of-step fault occurs, U cannot be guaranteedocVary continuously within each zoneThere is a possibility that a rejection will occur. Therefore, simply use UocThe out-of-step fault discrimination is difficult to realize by the amplitude change of the voltage. However, from the above analysis, it can be found that in UocNear the zero crossing point, the step-out and synchronous oscillation and short-circuit fault are different, thereby avoiding the U faultocAmplitude variations lead to the problem of motion rejection. Therefore, by utilizing the characteristic, the method and the device for the step-out protection of the impedance type generator can be obtained by introducing the change rule of the oscillation center voltage into the impedance plane.
Analyzing the oscillation center voltage U as shown in FIG. 1ocThe relationship between the variation law and the impedance characteristics measured at the terminal. ZΣThe voltage at 2 is the oscillation center voltage Uoc. When oscillation occurs, the oscillation center voltage UocGradually decreasing to a predetermined value, further decreasing to zero, and increasing in reverse direction after zero crossing, thus, by | UocThe constant value is used as an analysis condition to indicate the impedance characteristics measured at the machine end.
Wherein,for the purpose of the line current, it is,is the voltage at the infinite bus-bar,is the impedance at the infinite bus-bar,as to the angle of its impedance, the impedance angle,is the voltage at the center of the oscillation,is the impedance at the center of the oscillation,is its impedance angle, kmThe ratio of the voltage at the center of oscillation to the voltage amplitude at the infinite bus is generally consideredThen k ismRepresents the voltage value at the oscillation center, so there are:
|Zoc|/Zsy|＝km
further, the following relationship is provided:
wherein Z isΣRepresenting the total impedance of the generator to the infinite bus. And is provided with
The above equation is a circular equation called the isobaric boundary circle. The circle center and the radius are respectively as follows:
Zsythe impedance circle intersects A, B with its diameter at two points, whose coordinates are:
it can be seen from the above derivation that when the oscillation center voltage U is equal toocAt a certain value, the impedance Z observed at the infinite bussyThe variation locus is a circle.
When the voltage at the center of oscillation is kmThe resulting circle is reduced and an inclusion relationship is formed, which is represented in FIG. 3, where k is1＜k2＜k3The distribution forms isobaric boundary circles of different sizes. A certain oneDetermined voltage k at the center of oscillationmCorresponding to a circular curve on the impedance plane at the infinite bus, when the impedance track enters the circle, it indicates that the oscillation center voltage is less than km. Wherein, according to the actual conditions of engineering, when oscillation occurs, the oscillation center voltageMay be small, up to a minimum of 0.3-0.4, so if k ismThe larger value may cause the impedance trace to be always from k in a certain oscillation periodmAnd the step loss judgment cannot be carried out in the isobaric boundary circle with the determined value. Taking into account a certain margin, k may be takenmAnd (3) 0.2, ensuring that the impedance track can cross the impedance circle once in one oscillation period when the step-out fault occurs. The process reflects the change process of the oscillation center voltage, namely, when oscillation occurs, the oscillation center voltage is gradually reduced to a certain preset value, further is continuously reduced to zero, and is reversely increased after zero crossing until the amplitude is larger than the preset value. In conjunction with measuring the impedance trace characteristics at the oscillation timing end, neglecting the stator resistance r, the oscillation center voltage zero crossing point (i.e., when δ is 180 °) corresponds to the moment when the impedance trace crosses the reactance axis. The impedance at the infinite bus is added into the connection reactance and the transformer reactance, so that the expression of the impedance measured at the terminal can be obtained, and the change of the numerical value does not influence the inclusion relation characteristic of the isobaric boundary circle on the impedance plane at the terminal. Therefore, if the impedance trace measured at the terminal enters from a certain kmThe isobaric boundary circle on the impedance plane at the end of the numerically determined terminal indicates that the oscillation center voltage is lower than a certain value. The relation can reflect the change rule of the oscillation center voltage, and the step-out fault is detected.
Therefore, the generator step-out protection method comprises the following steps:
A. acquiring the total impedance of the generator to an infinite bus;
B. determining an isobaric boundary circle of an impedance plane at an infinite bus according to the total impedance;
C. transforming the isobaric boundary circle to an isobaric boundary circle on an impedance plane at the machine end;
D. measuring the end impedance, determining the generator as acceleration out-of-step when the end impedance penetrates from the right side and the left side of the isobaric boundary circle within a preset time, and executing acceleration out-of-step protection; and when the impedance at the generator end penetrates in from the left side and penetrates out from the right side of the isobaric boundary circle within preset time, determining that the generator is decelerated and desynchronized, and executing deceleration and desynchronization protection.
From the above analysis, when the machine end impedance penetrates into the right side and penetrates out of the left side of the isobaric boundary circle within the predetermined time, the change process of the oscillation center voltage is described as follows: the oscillation center voltage is gradually reduced to a certain preset value, further continuously reduced to zero, and reversely increased after zero crossing until the amplitude is larger than the preset value. This indicates that the generator has experienced an accelerated loss of mains and that accelerated loss of mains protection should be performed. When the impedance of the machine end penetrates in from the left side and penetrates out from the right side of the isobaric boundary circle within the preset time, the change process of the oscillation center voltage is shown as follows: the oscillation center voltage is gradually increased from a negative value to a certain preset value, then is continuously increased to zero, and is reversely increased after zero crossing until the amplitude is larger than the preset value. This indicates that the generator has experienced a deceleration step-out and that an accelerated step-out protection should be performed.
In the embodiment of the present invention, the determination method of the isobaric limit circle is further refined, but those skilled in the art will appreciate that the method can be modified by the foregoing embodiment, or the oscillation center can be directly measured
The reaction of the voltage at the impedance plane determines the isobaric boundary circle.
In another embodiment of the present invention, the method for determining the isobaric limit circle is determined as follows:
the circle center of the isobaric boundary circle is <math>
<mrow>
<mfrac>
<mrow>
<msub>
<mi>Z</mi>
<mi>Σ</mi>
</msub>
<mo>/</mo>
<mn>2</mn>
</mrow>
<mrow>
<msubsup>
<mi>k</mi>
<mi>m</mi>
<mn>2</mn>
</msubsup>
<mo>-</mo>
<mn>1</mn>
</mrow>
</mfrac>
<mo>,</mo>
</mrow>
</math> Radius of
Wherein ZΣThe total impedance of the generator to the infinite bus;
kma voltage that is the center of oscillation;
the difference between the impedance angle at the oscillation center and the impedance angle at the infinite bus;
through the mode, the isobaric boundary circle can be determined without measuring impedance change, so that the method is quick and effective, and the accuracy of the generator step-out protection method is improved.
From the above analysis, it can be seen that, according to the actual engineering situation, when oscillation occurs, the oscillation center voltageMay be small, up to a minimum of 0.3-0.4, so if k ismThe larger value may cause the impedance trace to be always from k in a certain oscillation periodmWithin the circle defined by the values.
Thus, in yet another embodiment of the present invention, for kmIs limited by taking kmThe value is 0.2, and experiments prove that the value can quickly determine the step-out fault of the generator and has good discrimination. What is needed isThe step C of transforming the isobaric boundary circle into an isobaric boundary circle on an impedance plane at the end is as follows:
in the above embodiment, the diameter is displaced by X in the circles+XtObtaining an isobaric boundary circle on an impedance plane at the terminal;
wherein XsReactance, X at bus of infinitetIs the transformer reactance.
The manner of the out-of-step protection may be active investment protection, may be adjusting parameters, etc., and may be selected by one skilled in the art in light of the teachings of the disclosed embodiments of the present invention.
As a specific embodiment of the present invention, when the generator is a non-salient pole machine, the acceleration step-out protection is to send an acceleration step-out signal to the non-salient pole machine and reduce the output of a prime mover. The deceleration step-out protection is to send out deceleration step-out signals to the non-salient pole machine and increase the output of a prime motor.
As another specific embodiment of the present invention, when the generator is a salient pole machine, the acceleration step-out protection and/or the deceleration step-out protection is to perform a cutting machine operation.
After different accelerating out-of-step protection/decelerating out-of-step protection modes are adopted for different generator types, different types of generators can be protected in a targeted mode.
In the above embodiment, the predetermined time is determined by the shortest oscillation period, so that the person skilled in the art can select the predetermined time Δ t according to the oscillation characteristics of the actual generator system.
In one embodiment, the predetermined time Δ t is 25ms to 50 ms. Experiments verify that most of the acceleration or deceleration out-of-step is done in this phase.
In particular, in another embodiment, the predetermined time Δ t is 40 ms. Based on the statistical data, the shortest oscillation period of the system oscillation can be 0.2s, and the maximum value of the oscillation center voltage in one oscillation period is1, consider taking kmWhen the step loss fault occurs, the shortest time required for the impedance track to pass from the isobaric boundary circle on the impedance plane at the entry end to the isobaric boundary circle on the impedance plane at the exit end is as follows: 200ms (0.21) ═ 40ms, therefore, Δ t was determined to be 40 ms.
The following description of fig. 4 illustrates a specific embodiment of the present invention.
Through the center of a circleRadius ofTo determine the isobaric boundary circle at infinite generatrix.
By displacement of X over the diameter of the circles+XtResulting in an isobaric boundary circle on the impedance plane at the termination.
The right half arc of an isobaric boundary circle on an impedance plane at the machine end is a curve I, the left half arc is a curve II, the impedance at the machine end is measured, when the impedance at the machine end penetrates in from the right side and penetrates out from the left side of the isobaric boundary circle within preset time (40 ms in the embodiment), namely when the impedance track is shown as a curve a in the figure, the generator is determined to be in accelerated step loss, and accelerated step loss protection is executed; when the terminal impedance penetrates into the left side and penetrates out of the right side of the isobaric boundary circle within a preset time (40 ms in the embodiment), namely the impedance trace is shown as a curve b in the figure, the generator is determined to be decelerated and desynchronized, and the deceleration and desynchronized protection is executed. Further, when the impedance locus changes according to the curve c, the fault is the occurrence of a three-phase short circuit, and when the impedance locus changes according to the curve d, the fault is the occurrence of synchronous oscillation. Therefore, in the embodiment of the invention, various faults of the generator are well distinguished, and the monitoring precision is high.
In order to realize the generator step-out protection method, the invention also discloses a generator step-out protection device, which comprises the following steps:
the impedance obtaining unit is used for obtaining the total impedance from the generator to an infinite bus;
the isobaric boundary circle calculation unit is connected to the impedance acquisition unit and used for determining an isobaric boundary circle on an impedance plane at an infinite bus according to the total impedance;
the isobaric boundary circle transformation unit is connected to the isobaric boundary circle calculation unit and is used for transforming the isobaric boundary circle on the impedance plane at the infinite bus into the isobaric boundary circle on the impedance plane at the terminal;
a terminal impedance measuring unit for measuring terminal impedance;
the generator step-out judging unit is connected to the extreme impedance measuring unit and the isobaric boundary circle transforming unit, and determines that the generator is out of step in an acceleration mode when the machine-end impedance penetrates from the right side and penetrates out of the left side of the isobaric boundary circle on the impedance plane at the end in a preset time, and determines that the generator is out of step in a deceleration mode when the machine-end impedance penetrates from the left side and penetrates out of the right side of the isobaric boundary circle on the impedance plane at the end in the preset time;
and the step-out protection unit is connected to the generator and the step-out judgment unit of the generator and is used for executing acceleration step-out protection or deceleration step-out protection according to the step-out type.
It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and should not be construed as limiting the scope of the present invention, and any minor changes and modifications to the present invention are within the scope of the present invention without departing from the spirit of the present invention.
Claims (10)
1. A method of generator step-out protection, the method comprising the steps of:
A. acquiring the total impedance of the generator to an infinite bus;
B. determining an isobaric boundary circle of an impedance plane at an infinite bus according to the total impedance;
C. transforming the isobaric boundary circle to an isobaric boundary circle on an impedance plane at the machine end;
D. measuring the impedance of the machine end, determining the generator as accelerating step loss when the impedance of the machine end penetrates into the right side and penetrates out of the left side of an isobaric boundary circle on an impedance plane of the machine end within preset time, and executing the accelerating step loss protection; and when the impedance at the machine end penetrates into the left side and penetrates out of the right side of the isobaric boundary circle on the impedance plane at the machine end in a preset time, determining that the generator is decelerated and desynchronized, and executing deceleration and desynchronization protection.
2. The method for generator step-out protection as recited in claim 1, wherein said step B of determining an isobaric boundary circle of the impedance plane at infinite bus comprises:
the center of a circle is <math>
<mrow>
<mfrac>
<mrow>
<msub>
<mi>Z</mi>
<mi>Σ</mi>
</msub>
<mo>/</mo>
<mn>2</mn>
</mrow>
<mrow>
<msubsup>
<mi>k</mi>
<mi>m</mi>
<mn>2</mn>
</msubsup>
<mo>-</mo>
<mn>1</mn>
</mrow>
</mfrac>
<mo>,</mo>
</mrow>
</math> Radius of
Wherein ZΣThe total impedance of the generator to the infinite bus;
kma voltage that is the center of oscillation;
the difference between the impedance angle at the oscillation center and the impedance angle at the infinite bus;
3. the method of generator step-out protection as recited in claim 2 wherein k ismThe value is 0.2.
4. The generator step-out protection method of claim 1 wherein the transformation of the isobaric boundary circle to an isobaric boundary circle on the impedance plane at the generator end in step C is:
at circular diameter displacement Xs+XtObtaining an isobaric boundary circle on an impedance plane at the terminal;
wherein XsReactance, X at bus of infinitetIs the transformer reactance.
5. The method for generator step-out protection according to any one of claims 1 to 4, wherein the generator is a non-salient pole machine, and correspondingly the step-out protection is to send out a step-out signal to the non-salient pole machine and reduce the output of a prime mover.
6. The method for protecting generator from step loss according to any one of claims 1 to 4, wherein the generator is a non-salient pole machine, and correspondingly the deceleration step loss protection is to send a deceleration step loss signal to the non-salient pole machine and increase the output of a prime mover.
7. Generator step-out protection method according to any of claims 1-4, wherein the generator is a salient pole machine and correspondingly the acceleration step-out protection and/or deceleration step-out protection is a generator tripping operation.
8. The method of generator step-out protection as recited in claim 1 wherein said predetermined time is between 25ms and 50 ms.
9. The method of generator step-out protection as recited in claim 1 wherein said predetermined time is 40 ms.
10. A generator step-out protection device, the generator step-out protection device comprising:
the impedance obtaining unit is used for obtaining the total impedance from the generator to an infinite bus;
the isobaric boundary circle calculation unit is connected to the impedance acquisition unit and used for determining an isobaric boundary circle of an impedance plane at an infinite bus according to the total impedance;
the isobaric boundary circle transformation unit is connected to the isobaric boundary circle calculation unit and is used for transforming the isobaric boundary circle of the impedance plane at the infinite bus into the isobaric boundary circle on the impedance plane at the terminal;
a terminal impedance measuring unit for measuring terminal impedance;
the generator step-out judging unit is connected to the extreme impedance measuring unit and the isobaric boundary circle transforming unit, and determines that the generator is out of step in an acceleration mode when the machine-end impedance penetrates from the right side and penetrates out of the left side of the isobaric boundary circle on the impedance plane at the end in a preset time, and determines that the generator is out of step in a deceleration mode when the machine-end impedance penetrates from the left side and penetrates out of the right side of the isobaric boundary circle on the impedance plane at the end in the preset time;
and the step-out protection unit is connected to the generator and the step-out judgment unit of the generator and is used for executing acceleration step-out protection or deceleration step-out protection according to the step-out type.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410546889.3A CN104242245B (en) | 2014-10-16 | 2014-10-16 | Generator out-of-step protection method and apparatus |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105048636A (en) * | 2015-09-01 | 2015-11-11 | 华中科技大学 | Power generator hierarchical out-of-step protection method |
| CN106683561A (en) * | 2017-02-20 | 2017-05-17 | 苏州市职业大学 | Processing demonstration system for mechanical teaching |
| CN107134776A (en) * | 2017-06-27 | 2017-09-05 | 华北电力大学 | The centralized positioning of multi frequency system asynchronous oscillation and displacement path tracing system and method |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105048636A (en) * | 2015-09-01 | 2015-11-11 | 华中科技大学 | Power generator hierarchical out-of-step protection method |
| CN106683561A (en) * | 2017-02-20 | 2017-05-17 | 苏州市职业大学 | Processing demonstration system for mechanical teaching |
| CN106683561B (en) * | 2017-02-20 | 2022-12-30 | 苏州市职业大学 | Machining demonstration system for mechanical teaching |
| CN107134776A (en) * | 2017-06-27 | 2017-09-05 | 华北电力大学 | The centralized positioning of multi frequency system asynchronous oscillation and displacement path tracing system and method |
| CN107134776B (en) * | 2017-06-27 | 2020-11-03 | 华北电力大学 | System and method for positioning out-of-step oscillation center and tracking displacement path of multi-frequency system |
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| CN104242245B (en) | 2017-06-13 |
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