CN1804644B - Method for capturing out-of-step interface based on reactive power - Google Patents

Abstract

The invention discloses a method for quoting the step-out centre of the involved interconnected power system. It uses the device to collect the integral quantity of the instantaneous value of reactive power in a step-out period to quote the step-out cross mutual connection of the step-out centre to ascertain the step-out cross. It uses the active zero cross to quote the oscillation period and integer to the reactive power in the period to quote the step-out cross mutual connection of the step-out centre and forecast the moving direction of the step-out center.

Description

Seek the method for step-out section based on reactive power

Technical field

The present invention relates to seek after a kind of electric system step-out the method that the step-out section carries out off-the-line, at the step-out section system is carried out off-the-line and help calming down vibration between the step-out system, avoid accidents such as generation systems collapses, has a power failure on a large scale.

Background technology

Both at home and abroad the generation of major accident nearly all is to enlarge because of system's unstability, because of there not being predetermined countermeasure, develops into disastrous consequence.Operation practice shows, although to the increasingly stringent that requires of system stability, measure is perfect day by day, always because of the stack of some prior unpredictable accidentalia, produces the accident of stability disruption, causes the step-out of system.In transferring electricity from the west to the east, under the interconnected condition in north and south, China will form on national network gaint power system, if major accident, its scale might increase considerably with the loss that causes.The step-out off-the-line is to guarantee the unlikely last line of defense of collapse fully of whole electrical network as the important measures that guarantee system safety operation, is the important measures that various countries' power system safety and stability control is generally adopted.The system decomposition of suitably naming a person for a particular job in electric system becomes two or several subsystems, makes by frequency not wait and that two parts system of vibration takes place is out of touch, thereby has also just eliminated vibration, avoids accident in system-wide further expansion.Under the asynchronous mode, in the cycle, minimum that of voltage is called out-of-step center on the step-out section interconnection at an asynchronous oscillation.The step-out disconnection device that is applied at present in the electric system substantially all is the position of measuring apparent impedance method or minimum voltage method judgement out-of-step center by minimum, judges that it is above circuit that whether is positioned at device control.Along with the interconnected development of electric system, these two kinds of methods have been difficult to adapt to the situation of the complicated interconnected electric power system of present Da Qu.Particularly, when the hinge bus connects many interconnections, and the step-out section all do not comprise this bus and connected interconnection the time, be difficult to effectively distinguish step-out section interconnection and non-step-out section interconnection based on minimum measuring voltage or minimum apparent impedance.

In the complicated electric power system of reality, judge that exactly the step-out section is very important.Because if can not implement off-the-line at system's step-out section exactly, then system oscillation is not eliminated.

After the electric system step-out, by the step-out section with system sectionalizing can make by frequency do not wait take place the vibration two parts system out of touch, thereby oscillation-damped avoids accident in system-wide further expansion.China's " power system safety and stability guide rule " clearly stipulates: operating electric system must be provided with splitting point in suitable place, and the installing automatic splitting device.When system's generation stability disruption, can in a planned way system be separated rapidly and reasonably and classify supply and demand balance (measures such as the hydraulic turbine, low frequency self-starting hydrogenerator of cutting with automatic low-frequency rate load shedding, overfrequency match) as far as possible as, and the two or several parts of each self-sustaining synchronous operation.Anti-locking system for a long time can not pull-in step or is caused system frequency and collapse of voltage, the expansion accident.In oscillation period, the voltage magnitude minimum of (out-of-step center) is always arranged a bit on each bar step-out section interconnection.Out-of-step center is on the electric on line between two step-out group of planes, and therefore two subsystems implementing in the out-of-step center both sides after off-the-line generally can guarantee off-the-line keep (can cooperate some ancillary methods) synchronously separately substantially.The step-out disconnection device is only after determining that out-of-step center is on the interconnection that disconnection device controls, sending the off-the-line order implements off-the-line and might guarantee that just synchronous (accent) of each subsystem moves after the off-the-line, and then calm down vibration in the system, the accident that prevents enlarges, and avoids causing the accident of the long-time large-area power-cuts of system.Therefore, domestic disconnection device substantially all will remove to catch out-of-step center by the whole bag of tricks, when " determining that out-of-step center drops on this circuit ", just carries out off-the-line.

At present, whether the position that the minimum voltage value of oscillating voltage envelope or the minimum measured value of apparent impedance are differentiated out-of-step center when being applied to many employings of the step-out disconnection device system asynchronous oscillation of electric system is among the operating space, and determines the step-out section based on this.But this method is applicable to system relatively simple for structure, and for the interconnected electric power system of complexity, often is difficult to reach off-the-line requirement accurately and fast; Domestic disconnection device is based on the position that single-ended local amount is judged out-of-step center substantially, and this can't determine the out-of-step center position, is at most in which direction.Single-ended amount is caught out-of-step center, is difficult to accurately determine the interconnection that out-of-step center really is positioned at, and is difficult to effectively adapt to the requirement that the Da Qu interacted system is caught the step-out section; When the line construction complexity, particularly exist the single busbar node to be connected with under the situation of many interconnections, be difficult to accurately judge the step-out section really which bar interconnection is made of, be difficult in other words judge exactly out-of-step center really is present among which the bar interconnection that constitutes the step-out section.

Summary of the invention

The purpose of this invention is to provide a kind of method that can carry out accurately, fast judge out-of-step center to the interconnected electric power system of complexity.

The present invention takes following technical scheme to realize:

Based on the method for reactive power searching step-out section, it is characterized in that the instantaneous value of the reactive power that use device collects removes to judge the step-out section interconnection at out-of-step center place in the size of the integrated value of a step-out in the cycle, thereby determine the step-out section.

The aforesaid method of seeking the step-out section based on reactive power, the method that it is characterized in that wherein said searching step-out section is to utilize meritorious zero passage to judge oscillation period and in this cycle reactive power is carried out integration, thereby judges which bar interconnection out-of-step center drops on and can predict the moving direction of out-of-step center.

Aforesaid method based on reactive power searching step-out section is characterized in that it comprises the following steps:

(1) represents equivalent generator with amplitude simple harmonic electromotive force source fixing, after the virtual impedance; Supposing the system angle of impedance and line impedance angle equate, and with the equivalent impedance reduction of system in the interconnection impedance; The system synthesis resistance value is invariable, ignores the influence of system loading trend;

(2) out-of-step center be an asynchronous oscillation in the cycle on the step-out section interconnection voltage magnitude minimum that appears;

(3) reactive power in the oscillation period is carried out integration, monocycle inactivity integration be zero point just near out-of-step center, and be positioned at the less relatively side of equivalent electromotive force amplitude.

The aforesaid method of seeking the step-out section based on reactive power, the direction that it is characterized in that the described out-of-step center of step 3 wherein judges it is that the positive dirction of definition electric current is to flow to circuit by bus, when the positive dirction of electric current is pointed to out-of-step center, think the positive dirction of out-of-step center at measurement point; When the positive dirction of electric current is left out-of-step center, think the opposite direction of out-of-step center at measurement point.

Aforesaid method based on reactive power searching step-out section is characterized in that determining that based on the integrated value of reactive power in the unit step-out cycle criterion formula of out-of-step center position is

∫ _t1 ^t2Q(t)dt＜-|Qset| (13)

∫ _t1 ^t2Q(t)dt＞+|Qset| (14)

|∫ _t1 ^t2Q(t)dt|≤|Qset| (15)

Formula (13) and formula (14) they are to determine the criterion of out-of-step center locality, wherein | and Qset| is the setting valve of reactive power monocycle integrated value; Consider the swing of reactive power, the variation of the equivalent electromotive force in both sides and the actual parameter of electrical network, set suitable reactive power setting valve; The idle integration setting valve of formula (13)-Shi (15) also can be adjusted respectively, especially to unitary device, in the locality of determining out-of-step center, go to judge the residing scope of out-of-step center based on reactive power monocycle integrated value, thereby determine the actuating range of device; To many table apparatus, particularly the interconnection two ends all dispose the situation of disconnection device,, determine among the interconnection that out-of-step center really is positioned at by the cooperation strategy, and implement off-the-line the position judgment of out-of-step center by to each other; If integral and calculating display type (13) is set up, illustrate that out-of-step center is installing the reverse of installation place; If integral and calculating display type (14) is set up, the forward of out-of-step center in the device installation place is described; If integral and calculating display type (15) is set up, illustrate that out-of-step center is near the device installation place.

Below technical scheme of the present invention is made detail analysis:

Method based on interconnection reactive power searching step-out section of the present invention is: the instantaneous value of the reactive power that use device collects removes to judge the step-out section interconnection at out-of-step center place in the size of the integrated value of a step-out in the cycle, thereby determines the step-out section.Catch the method for out-of-step center and compare with traditional voltage or apparent impedance passed through, reactive power more can be applied to seizure to system's step-out section neatly because of having directivity.Judge in the measurement of multiple spot by reactive power, can judge exactly not only which bar interconnection out-of-step center drops on and can predict the moving direction of out-of-step center, be beneficial to the coordination between the disconnection device, realize reasonable and planned off-the-line, effectively eliminate system oscillation, avoid the generation of system's major break down.

The variation characteristic of step-out section interconnection electric parameters:

To equivalent two machine systems, the variation characteristic of electric parameters in the step-out process of the interconnection between two systems that the connection frequency does not wait is:

1, on the step-out section interconnection (out-of-step center) arranged a bit, the amplitude of variation of its voltage magnitude is obviously greater than other places of interconnection, and far away more apart from out-of-step center, and amplitude changes more little, promptly in the asynchronous oscillation process, there is tangible voltage gradient in step-out section interconnection;

2, in the actual transformable scope of the equivalent electromotive force in two ends, in the arbitrary position of step-out section interconnection, instantaneous active power all can zero passage in an oscillation period twice.

3, at an asynchronous oscillation in the cycle, comprehensive reactive power of cycle is by among the step-out section two side inflow step-out sections.This mainly is because have tangible voltage gradient on the step-out section interconnection.

Utilize meritorious zero passage to judge oscillation period and in this cycle reactive power is carried out integration, this integrated value can reflect these features of step-out section.Based on this, proposed to seek the method for step-out section based on reactive power.

Determine that based on the interconnection reactive power method of step-out section has following advantage:

1, when out-of-step center when connecting the bus place of many interconnections, be difficult to determine by traditional method of catching out-of-step center which bar interconnection out-of-step center really is on based on voltage or apparent impedance.Reactive power because of have directivity relatively more can flexible Application in analysis to the step-out system.Based at asynchronous oscillation integration to both-end or multiterminal reactive power in the cycle, compare the integration size by optical fiber vertical (mutually) connection, not only can judge one group of interconnection at out-of-step center place exactly and can predict the moving direction of out-of-step center, be convenient to the coordination between the disconnection device.

2,, can determine the step-out section interconnection at out-of-step center place based on interconnection both-end amount or multiterminal amount (particularly idle).Than abroad by real-time measurement phase angle and compare (very high to hardware requirements such as real-time and passages, and there is measuring error in influence such as non-constant and interference owing to system's transient state parameter in the transient state process) go to catch the method for out-of-step center, go to judge that by idle integration the method for out-of-step center position is relatively low to time requirement, and be easy to realize the reliability height.

3, considered in this method derivation proof procedure that the equivalent electromotive force in off-the-line section both sides does not wait and factor such as interconnection loss, hypothesized model is consistent with the feature of actual step-out system as far as possible;

4, this method adaptive system structural change or changes of operating modes automatically is promptly with the method for operation of system, the structure-irrelevant of electrical network;

5, this method is adjusted conveniently, is convenient to the user and uses;

6, this method mainly utilizes the general character of asynchronous oscillation to differentiate, and is beneficial to be applied in the Da Qu interacted system;

7, this method has been considered the ability that subsystem after the off-the-line keeps (accents) synchronously to move, and can effectively eliminate the vibration between system, the generation of accident such as avoid accident expansion, system crash, have a power failure on a large scale.

Description of drawings

Fig. 1 is equivalent dual systems;

Fig. 2 be on Fig. 1 system step-out section interconnection one oscillation period idle integration size distribution schematic diagram;

The equivalent three machine system diagrams of Fig. 3;

Figure is waved at the merit angle of Fig. 4 unit;

Each sampling node voltage magnitude figure of Fig. 5 interconnection L0102-1;

Fig. 6. each sampling node voltage magnitude figure of interconnection L0103;

Fig. 7. each sampling node voltage magnitude figure of interconnection L0302;

Each segmentation active power of Fig. 8 interconnection L0102-1 and reactive power instantaneous value;

Each segmentation active power of Fig. 9 interconnection L0103 and reactive power instantaneous value;

Each segmentation active power of Figure 10 interconnection L0302 and reactive power instantaneous value;

Embodiment

Method shown in Fig. 1-10 based on reactive power searching step-out section:

Fig. 1 is equivalent two machine systems, adopts following equivalent condition in analysis:

Represent equivalent generator with amplitude simple harmonic electromotive force source fixing, after the virtual impedance; Supposing the system angle of impedance and line impedance angle equate, use The expression, and with system equivalent impedance reduction in the interconnection impedance, promptly the interconnection both end voltage is exactly With The system synthesis impedance is Z _∑, in the actual transformable scope of frequency, think Z _∑Value invariable; Ignore the influence of system loading trend.

During power system oscillation, equivalent electromotive force amplitude is actual to be unequal, the power taking gesture Be reference vector,

Amplitude be

K _eDoubly, the merit angular difference between two systems is δ, then

${\stackrel{\·}{E}}_M=k_e{\stackrel{\·}{E}}_N{e}^{\mathrm{j\δ}}---\left(1\right)$

Equivalent electric potential difference between two systems is

The electric current of interconnection is

Suppose that the disconnection device mounting points is a D point among Fig. 1, makes Z ₁Be of the impedance of the equivalent generator neutral point of M side to measurement point.Make k=Z ₁/ Z _∑, k represents the position of measurement point in total system, k ∈ (0,1).The voltage of measurement point is

${\stackrel{\&CenterDot;}{U}}_D={\stackrel{\&CenterDot;}{E}}_M-\stackrel{\&CenterDot;}{I}\&CenterDot;{\mathrm{<figure-callout\; id="1"\; label="Z"\; filenames="H05137658020050222E000021.png,H05137658020050222E000023.png"\; state="\{\{state\}\}">Z</figure-callout>}}_1=E_N\&CenterDot;[k_e(1-k)\cos \mathrm{\&delta;}+k+j{k}_e(1-k)\sin \mathrm{\&delta;}]---\left(4\right)$

${\left|U_D\right|}^2={\mathrm{<figure-callout\; id="2"\; label="E\; N"\; filenames="H05137658020050222E000021.png,H05137658020050222E000023.png"\; state="\{\{state\}\}">E</figure-callout>}}_N^{}\&CenterDot;[k_e^2{(1-k)}^2+2k_e(1-k)k\cos \mathrm{\&delta;}+{\left(k\right)}^2]---\left(5\right)$

When δ=π,

${\left|U_D\right|}^2={\mathrm{<figure-callout\; id="2"\; label="E\; N"\; filenames="H05137658020050222E000021.png,H05137658020050222E000023.png"\; state="\{\{state\}\}">E</figure-callout>}}_N^{}\&CenterDot;{(1+k_e)}^2\&CenterDot;{(k-\frac{{\mathrm{<figure-callout\; id="1"\; label="k\; e"\; filenames="H05137658020050222E000021.png,H05137658020050222E000023.png"\; state="\{\{state\}\}">k</figure-callout>}}_e}{1+k_e})}^2---\left(6\right)$

Know by formula (6), work as k=k _e/ (1+k _e) time, the voltage magnitude of measurement point is zero.To equivalent two machine systems, definition is when δ=k π (k ∈ odd number), and voltage magnitude is that zero that is out-of-step center (Center ofOut-of-step) on the interconnection.Out-of-step center be an asynchronous oscillation in the cycle on the step-out section interconnection voltage magnitude that of minimum appears.

Definition trend positive dirction is from M to N, and the applied power of device mounting points is:

Separating formula (7) can get

Make ke＞1 analyze now, can directly obtain by symmetry for the situation of ke＜1.

The integration of reactive power is in an oscillation period

$f_1\left(k\right)={\&Integral;}_0^{2\mathrm{\&pi;}}\mathrm{Qd\&delta;}$

Differentiate gets to k with formula (10)

Because

So function f ₁(k) be monotone decreasing about variable k, when $k<{\mathrm{<figure-callout\; id="2"\; label="k\; e"\; filenames="H05137658020050222E000021.png,H05137658020050222E000023.png"\; state="\{\{state\}\}">k</figure-callout>}}_e^{}/({\mathrm{<figure-callout\; id="2"\; label="k\; e"\; filenames="H05137658020050222E000021.png,H05137658020050222E000023.png"\; state="\{\{state\}\}">k</figure-callout>}}_e^{}+1)$ The time, f ₁(k)＞0; When $k={\mathrm{<figure-callout\; id="2"\; label="k\; e"\; filenames="H05137658020050222E000021.png,H05137658020050222E000023.png"\; state="\{\{state\}\}">k</figure-callout>}}_e^{}/({\mathrm{<figure-callout\; id="2"\; label="k\; e"\; filenames="H05137658020050222E000021.png,H05137658020050222E000023.png"\; state="\{\{state\}\}">k</figure-callout>}}_e^{}+1)$ The time, f ₁(k)=0; When $k>{\mathrm{<figure-callout\; id="2"\; label="k\; e"\; filenames="H05137658020050222E000021.png,H05137658020050222E000023.png"\; state="\{\{state\}\}">k</figure-callout>}}_e^{}/({\mathrm{<figure-callout\; id="2"\; label="k\; e"\; filenames="H05137658020050222E000021.png,H05137658020050222E000023.png"\; state="\{\{state\}\}">k</figure-callout>}}_e^{}+1)$ The time, f ₁(k)＜0.

When equivalent electromotive force when constant, the monocycle at out-of-step center place, idle integrated value was

In practical power systems, both sides system equivalent electromotive force is than ke ≈ 1, so out-of-step center is that zero point is very little apart from idle integration of monocycle on the interconnection, promptly $k_e/(k_e+1)\&ap;{\mathrm{<figure-callout\; id="2"\; label="k\; e"\; filenames="H05137658020050222E000021.png,H05137658020050222E000023.png"\; state="\{\{state\}\}">k</figure-callout>}}_e^{}/({\mathrm{<figure-callout\; id="2"\; label="k\; e"\; filenames="H05137658020050222E000021.png,H05137658020050222E000023.png"\; state="\{\{state\}\}">k</figure-callout>}}_e^{}+1),$ Therefore can think idle integration of monocycle be zero point just near out-of-step center, and be positioned at the less relatively side of equivalent electromotive force amplitude.

Shown in Figure 2 is when the equivalent electromotive force constant amplitude in both sides and ke＞1, the distribution trajectory diagram of reactive power monocycle integrated value on step-out section interconnection.Know that by this figure reactive power monocycle integrated value is dull and distributes on interconnection, therefore also can utilize the size of monocycle reactive power integrated value to remove to determine the actuating range of device.

A large amount of emulation and practice show, in system's asynchronous oscillation process, the equivalent electromotive force in both sides is not to wait and constantly variation, but among comprehensive reactive power of cycle always flows to the step-out section from step-out section both sides.

The positive dirction of definition electric current is to flow to circuit by bus.When the positive dirction of electric current is pointed to out-of-step center, think the positive dirction of out-of-step center at measurement point; When the positive dirction of electric current is left out-of-step center, think the opposite direction of out-of-step center at measurement point.

The criterion formula of determining the out-of-step center position based on the integrated value of reactive power in the unit step-out cycle is

${\&Integral;}_{t_1}^{t_2}Q\left(t\right)\mathrm{dt}<-\left|Q_{\mathrm{set}}\right|---\left(13\right)$

${\&Integral;}_{t_1}^{t_2}Q\left(t\right)\mathrm{dt}>+\left|Q_{\mathrm{set}}\right|---\left(14\right)$

$I\left|{\&Integral;}_{t_1}^{t_2}Q\left(t\right)\mathrm{dt}\right|\&le;\left|Q_{\mathrm{set}}\right|---\left(15\right)$

Formula (13) and formula (14) they are to determine the criterion of out-of-step center locality, wherein | and Q _Set| be the setting valve of reactive power monocycle integrated value.Consider the swing of reactive power, the variation of the equivalent electromotive force in both sides and the actual parameter of electrical network, set suitable reactive power setting valve.The idle integration setting valve of formula (13)-Shi (15) also can be adjusted respectively, especially to unitary device, in the locality of determining out-of-step center, go to judge the residing scope of out-of-step center based on reactive power monocycle integrated value, thereby determine the actuating range of device; To many table apparatus, particularly the interconnection two ends all dispose the situation of disconnection device,, determine among the interconnection that out-of-step center really is positioned at by the cooperation strategy, and implement off-the-line the position judgment of out-of-step center by to each other.If integral and calculating display type (13) is set up, illustrate that out-of-step center is installing the reverse of installation place; If integral and calculating display type (14) is set up, the forward of out-of-step center in the device installation place is described; If integral and calculating display type (15) is set up, illustrate that out-of-step center is near the device installation place.In logic, formula (15) can be lower with voltage (for example, voltage be lower than ratings 18%) phase " and with ", judge that out-of-step center is whether near device.Sampled point t ₁With sampled point t ₂Between time span determine that according to concrete vibration situation select 1 oscillation period usually, this can match with the active power zero passage, meritorious zero passage is for twice an oscillation period on the step-out section interconnection.For equivalent two machine systems, active power is zero passage first when both sides merit angular difference reaches 180 ° greatly, it has been generally acknowledged that on the engineering that this moment, system experienced from being synchronized to the transition state of step-out.Determine that by meritorious zero passage the asynchronous oscillation Cycle Length is not only very suitable, accurate, and realize simple.And then judge the position of out-of-step center according to the size of integral result.

Emulation of the present invention illustrates institute's equivalent three machine system simulation models of doing and trend reference direction as shown in Figure 3, and simulation system parameters all comes from the actual electric network model parameter, studies by this model is carried out transient emulation.0.12 during second, the three-phase shortcircuit accident has taken place in interconnection L0102-2.Excise this interconnection through main protection correct operation after 0.1 second, asynchronous oscillation appears in system.The merit angle geometric locus figure that is unit G2 and unit G3 with respect to unit G1 shown in Figure 4.By this figure as seen, unit G2 and G3 step-out are in unit G1.The step-out section as shown in Figure 3.Uniform sampling 4 points in interconnection L0102-1, L0103 and L0302, this moment, each interconnection was divided into 5 sections successively along the trend reference direction.Fig. 5, Fig. 6 and Fig. 7 are respectively the voltage magnitude variation diagrams of each interconnection two ends bus and middle 4 sampled points.By the voltage magnitude variation diagram as can be known, step-out section interconnection is L0102-1 and L0103, and there is tangible voltage gradient in the step-out section circuit, and unit exists the voltage magnitude of a node to change in the middle of oscillation period maximum, the minimum voltage amplitude occurs, this node is positioned near the out-of-step center or is exactly out-of-step center.Fig. 8 and Fig. 9 are the active power that measures at each segmentation end along the trend reference direction of each segmentation on interconnection L0102-1 and the interconnection L0103 and the instantaneous value figure of reactive power.Be defined in the oscillation period, the integrated value of reactive power size is that the cycle is comprehensively idle.Known that by Fig. 8 and Fig. 9 step-out section interconnection instantaneous reactive that two ends are surveyed is partial to positive and negative both sides respectively, this explanation cycle is comprehensive idle to be certain part in the middle of flowing to from the interconnection two ends.It shown in table 1 and the table 2 the meritorious size of (oscillation period) idle integration and mean value thereof during twice of the zero passage continuously first.Wherein,

$\underset{\&OverBar;}{\&Integral;Q}={\&Integral;}_{t_1}^{t_2}Q\left(t\right)\mathrm{dt}---\left(16\right)$

$\&Integral;Q=\left[{\&Integral;}_{t_1}^{t_2}Q\left(t\right)\mathrm{dt}\right]/(t_2-t_1)---\left(17\right)$

In formula (16) and the formula (17), t ₁And t ₂It is a starting point and the terminal point in oscillation period.Known always have any to survey idle integration minimum on step-out section interconnection by table 1, it is big more to put idle integration absolute value away from this more.Idle integrated value is dull substantially and distributes.The idle distribution characteristics of Here it is step-out section interconnection.Know that by Fig. 5 out-of-step center is near the C point, and as shown in Table 1, idle integrated value drops in L4 (CD) section, is positioned at C point left side zero point.As shown in Table 2, idle integrated value drops in L9 (GH) section, and as shown in Figure 6, out-of-step center is near the G point.Shown in Figure 10 is the meritorious and idle instantaneous value figure of the interconnection L0302 between a people having the same aspiration and interest group of planes, on this interconnection synchronized oscillation takes place.

Know by above analysis, the cycle comprehensive idle always flow to section from step-out section both sides among, and its size is basic on step-out section interconnection becomes monotonicity to distribute.

For step-out section interconnection, cutting off from the interconnection two ends all is the same meaning from middle certain the some cut-out of interconnection still, is positioned among the cut interconnection as long as disconnection device can be judged out-of-step center.So load onto disconnection device respectively in the interconnection both sides between valve system of waiting shown in Figure 3, after system's step-out, at the fall into a trap idle integration of calculating apparatus installation place of each asynchronous oscillation cycle, respectively install the idle integrated value of installation place by optical fiber vertical (mutually) connection, judge the interconnection at out-of-step center place, thereby determine the step-out section of system and implement off-the-line.

The integral result of each a segmentation reactive power oscillation period of table 1 step-out section interconnection L01 02-1

The integral result of table 2 step-out section interconnection L01 03 each a segmentation reactive power oscillation period

The integral result (L0102-1) of table 1 a reactive power oscillation period

The integral result (L0103) of table 2 a reactive power oscillation period

The foregoing description does not limit the present invention in any form, and all technical schemes that form obtained of taking to be equal to replacement or equivalent transformation all drop within protection scope of the present invention.

Claims (4)

1. seek the method for step-out section based on reactive power, the instantaneous value that it is characterized in that the reactive power that use device collects removes to judge the step-out section interconnection at out-of-step center place in the size of the integrated value of a step-out in the cycle, be that integrated value is that the canonical out-of-step center is in device installation place positive dirction, integrated value is the opposite direction of negative then out-of-step center in the device installation place, thereby determines the step-out section.

2. the method for seeking the step-out section based on reactive power according to claim 1, the method that it is characterized in that wherein said searching step-out section is to utilize meritorious zero passage to judge oscillation period and in this cycle reactive power is carried out integration, thereby judges which bar interconnection out-of-step center drops on and can predict the moving direction of out-of-step center.

3. the method based on reactive power searching step-out section according to claim 1 is characterized in that it comprises the following steps:

(1) represents equivalent generator with amplitude simple harmonic electromotive force source fixing, after the virtual impedance; Supposing the system angle of impedance and line impedance angle equate, and with the equivalent impedance reduction of system in the interconnection impedance; The system synthesis resistance value is invariable, ignores the influence of system loading trend;

(2) active power zero crossing periodically during asynchronous oscillation is an asynchronous oscillation cycle between twice equidirectional zero passage, and described twice equidirectional zero passage promptly all served as reasons for twice negative to just or by just to negative zero passage;

(3) reactive power in the oscillation period is carried out integration, monocycle reactive power integration is that zero point is just near out-of-step center.

4. the method for seeking the step-out section based on reactive power according to claim 3, the direction that it is characterized in that the described out-of-step center of step 3 wherein judges it is that the positive dirction of definition electric current is to flow to circuit by bus, when the positive dirction of electric current is pointed to out-of-step center, think the positive dirction of out-of-step center at measurement point; When the positive dirction of electric current deviates from out-of-step center, think the opposite direction of out-of-step center at measurement point.

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