CN103269082A - Reverse oscillation suppression system and method of large-sized generator set subsynchronous oscillation - Google Patents

Abstract

The invention provides a reverse oscillation suppression system of large-sized generator set subsynchronous oscillation, and further provides a method of the large-sized generator set subsynchronous oscillation. The reverse oscillation suppression system of the large-sized generator set subsynchronous oscillation comprises a measurement processor, an inverted amplifier, a low-pass filter, a phase compensator and a power signal generation device. The reverse oscillation suppression system and method of the large-sized generator set subsynchronous oscillation does not need to make detailed analyses of the complex formation cause and process of subsynchronous oscillation and is clear in control principle. Specifically, each control module is easy to achieve in an engineering mode. The reverse oscillation suppression system and method of the large-sized generator set subsynchronous oscillation has strong practicability, is simple to control, convenient to install, flexible and fast, and is easily achieved in an engineering mode.

Description

The antihunt of Generator Set sub-synchronous oscillation suppresses system and method

Technical field

The present invention relates to Generator Set and stablize the control field, especially a kind of for the antihunt inhibition system and the control method thereof that suppress the Generator Set sub-synchronous oscillation.

Background technology

China has formed the electric power general layout of " transferring electricity from the west to the east " owing to energy skewness.This employing series compensation capacitance carries out the mode of big capacity, long distance power transmission, makes the sub-synchronous oscillation of Generator Set become an outstanding problem of electric power system.

Sub-synchronous oscillation belongs to the vibration unstability of system, and it is to be caused by a kind of special mechanical electric coupling in the electric power system.The harm of sub-synchronous oscillation maximum is that the heavy damage that possible cause the large steam turbine-generator set rotor axle to be causes a serious accident the security of operation of crisis electric power system.As early 1970s, the serious accident that the large steam turbine-generator set rotor macro-axis that U.S. Mohave power plant takes place damages.Togtoh, China Inner Mongol, on all, northeast Yi Min power plant, Shaanxi Jin Jie etc. send engineering, in practical application or analytical calculation, all found sub-synchronous oscillation problem in various degree.

According to the report of IEEE working group, the sub-synchronous oscillation braking measure mainly divides four classes: 1. damping and filtering; 2. relaying protection and monitoring and protecting; 3. system switching operation and unit excision; 4. the transformation of generating set and system.In the patent of the present invention, utilize the antihunt control method that sub-synchronous oscillation is suppressed, belong to damping and filtering method.By the antihunt control method, with the harmonic filtration in the sub-synchronous oscillation, the increase system is to the electrical damping of sub-synchronous oscillation.

Sub-synchronous oscillation is a kind of system's unstable phenomenon of complexity: at first, its generating process is very complicated, and what relate to a kind of prime mover shaft system and electrical system excites behavior mutually, belongs to the mechanical-electric coupling vibration; Secondly, its origin cause of formation is varied, the sub-synchronous oscillation that not only has common serial compensation capacitance to cause, and HVDC and some active quick control devices also can cause sub-synchronous oscillation; At last, its harmonic components is more complicated also, and steam turbine has several torsional oscillation modes, and sub-synchronous oscillation just has several possible frequencies.

Because these complexity of sub-synchronous oscillation, be suggested to suppress the control method of sub-synchronous oscillation at present, also can't apply in the engineering mostly and go, a lot of places that need research and discuss are arranged, as method for optimally controlling, neural net is regulated method, and by to the method for the POLE PLACEMENT USING CONTROLLER DESIGN of sub-synchronous oscillation etc.The present invention is intended to propose a kind of practical, and the system of being convenient to Project Realization suppresses sub-synchronous oscillation, and has proposed the control method of this inhibition system.

Summary of the invention

The object of the present invention is to provide a kind of antihunt to suppress system and control method thereof, the sub-synchronous oscillation that exists in the inhibition Generator Set ensures the safe operation of electric power system.Technical problem to be solved by this invention is with from the detected torsional mode component of system, is converted into the control signal of power electronic equipment by the inhibition system of antihunt, and antihunt inhibition system is reasonably controlled.

Among the present invention, it is as follows in the principle of sub-synchronous oscillation that antihunt suppresses systemic effect: when sub-synchronous oscillation took place, the axle of the electrical oscillation frequency of generator and steam turbine was a certain model frequency f _mComplementation, after disturbance took place, will flow through subsynchronous frequency on the generator unit stator was f ₀-f _mCurrent component (f ₀Be power frequency) because torque and the rotating speed deviation delta ω same-phase of its generation, the therefore effect that can produce negative damping, make vibration more and more serious, so realize the inhibition of sub-synchronous oscillation, will reduce the influence of subsynchronous frequency component in the stator current, namely reducing subsynchronous frequency is f ₀-f _mCurrent component.Antihunt control method, exactly with containing the measuring-signal of prime mover torsional mode component in the system, be converted into the grid power level electric current that offsets with it, by the power electronic equipment input system, thereby the system of elimination medium frequency is f ₀-f _mSubsynchronous frequency current, reduce the effect of negative damping of subsynchronous current component in the stator.

According to an aspect of the present invention, provide a kind of antihunt of Generator Set sub-synchronous oscillation to suppress system, comprise as lower device:

Measurement processor for the torsional mode component signal of measuring prime mover, is exported to inverting amplifier with the torsional mode component signal then;

Inverting amplifier is used for described torsional mode component is carried out anti-phase amplification, makes the signal after the anti-phase amplification can control power electronic equipment output grid power rank electric current, then the signal after the described anti-phase amplification is exported to low pass filter;

Low pass filter is used for the high-frequency signal that the signal after the described anti-phase amplification of filtering disturbs, then with filtered signal input phase compensator;

Phase compensator is used for described filtered signal is compensated because of the phase delay that electric power system and described measurement processor and low pass filter cause, then the signal after the phase compensation is exported to the power signal generating means;

The power signal generating means, it is the signal of power stage that the signal after the described phase compensation is transformed m, exports to electric power system, eliminates the subsynchronous component in the electric power system, suppresses sub-synchronous oscillation, the system that increases electric power is to the electrical damping of sub-synchronous oscillation.

Preferably, described torsional mode component is the signal that can reflect the sub-synchronous oscillation characteristic, the described signal of sub-synchronous oscillation characteristic that can reflect comprises generator speed deviation, machine end power output or high pressure cylinder rotating speed deviation, described low pass filter is used for the signal after the described anti-phase amplification is higher than the whole filterings of interference signal of power frequency.

Preferably, described measurement processor mainly is made of the transfer function H of described measurement processor a first order inertial loop ₁(s) be:

$H_1\left(s\right)=\frac{1}{1+s{T}_1}$ Formula 1

In the formula 1, T ₁Be time constant.

Preferably, described low pass filter adopts second-order low-pass filter, the transfer function H of described low pass filter ₂(s) be:

$H_2\left(s\right)\frac{{\mathrm{<figure-callout\; id="0"\; label="G"\; filenames="HSA00000883392500021.png"\; state="\{\{state\}\}">G</figure-callout>}}_0{{\mathrm{\&omega;}}_n}^2}{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="HSA00000883392500021.png"\; state="\{\{state\}\}">s</figure-callout>}}^2+\mathrm{\&xi;}{\mathrm{\&omega;}}_{n}s+{{\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HSA00000883392500021.png"\; state="\{\{state\}\}">n</figure-callout>}}}^2}$ Formula 2

In the formula 2, G ₀Be the logical gain of band of low pass filter, ω _nBe natural angular frequency, ξ is the damping coefficient of filter.

Preferably, the transfer function H of described phase compensator (s) is:

$H\left(s\right)=\frac{s-c}{s+c}$ Formula 3

In the formula 3, the value of parameter c is by determining with following formula 4:

Formula 4

In the formula 4, α ₁Phase deviation, α for the synchronizing frequency component ₂The phase deviation, the α that cause at model frequency for low pass filter ₃The time delay, the α that cause for measurement ₄Be the time delay that power electronic equipment may cause, ω _pFrequency for current sub-synchronous oscillation.

According to another aspect of the present invention, also provide a kind of antihunt inhibition method of Generator Set sub-synchronous oscillation, comprise the steps

Step 1: the torsional mode component signal of measuring prime mover;

Step 2: the anti-phase amplification of described torsional mode component that will measure makes the signal after the anti-phase amplification can control power electronic equipment output grid power rank electric current;

Step 3: the high-frequency signal that disturbs in the signal after the described anti-phase amplification of filtering;

Step 4: the phase delay that causes because of electric power system and described measurement processor and low pass filter in the described filtered signal is compensated;

Step 5: the signal after the described phase compensation is converted into the signal of power stage, exports to electric power system, eliminate the subsynchronous component in the electric power system, suppress sub-synchronous oscillation, the system that increases electric power is to the electrical damping of sub-synchronous oscillation.

Preferably, described torsional mode component is the signal that can reflect the sub-synchronous oscillation characteristic, the described signal of sub-synchronous oscillation characteristic that can reflect comprises generator speed deviation, machine end power output or high pressure cylinder rotating speed deviation, in described step 3, since all frequencies of oscillation in the sub-synchronous oscillation all at 10 hertz between the power frequency, so in the inhibition of sub-synchronous oscillation, do following processing:

-all are higher than all filterings of interference signal of power frequency; Perhaps

In-actual the engineering, disturb if power frequency component produces control system, then power frequency is also contained in the filtering scope of low pass filter, or increases the band stop filter of power frequency in addition.

Preferably, described step 1 particularly, utilizes measurement processor to realize that wherein, described measurement processor mainly is made of a first order inertial loop, the transfer function H of described measurement processor ₁(s) be:

$H_1\left(s\right)=\frac{1}{1+s{T}_1}$ Formula 1

In the formula 1, T ₁Be time constant.

Preferably, in described step 3 since sub-synchronous oscillation in all frequencies of oscillation all at 10 hertz between the power frequency, so in the inhibition of sub-synchronous oscillation, do following processing:

-all are higher than all filterings of interference signal of power frequency; Perhaps

In-actual the engineering, disturb if power frequency component produces control system, then power frequency be also contained in the filtering scope of low pass filter, or increase the band stop filter of power frequency in addition,

Particularly, utilize low pass filter to realize, wherein, described low pass filter adopts second-order low-pass filter, the transfer function H of described low pass filter ₂(s) be:

$H_2\left(s\right)\frac{{\mathrm{<figure-callout\; id="0"\; label="G"\; filenames="HSA00000883392500021.png"\; state="\{\{state\}\}">G</figure-callout>}}_0{{\mathrm{\&omega;}}_n}^2}{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="HSA00000883392500021.png"\; state="\{\{state\}\}">s</figure-callout>}}^2+\mathrm{\&xi;}{\mathrm{\&omega;}}_{n}s+{{\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HSA00000883392500021.png"\; state="\{\{state\}\}">n</figure-callout>}}}^2}$ Formula 2

In the formula 2, G ₀Be the logical gain of band of low pass filter, ω _nBe natural angular frequency, ξ is the damping coefficient of filter.

Preferably, described step 4 is brought compensating of delay to the measurement in the abovementioned steps, filtering link and power electronic equipment, in the practical application, by increase suitable leading-delay component, the angle of these delays is reduced to below 10 °,

Particularly, utilize phase compensator to realize that the transfer function H of described phase compensator (s) is:

$H\left(s\right)=\frac{s-c}{s+c}$ Formula 3

In the formula 3, the value of parameter c is by determining with following formula 4:

Formula 4

In the formula 4, α ₁Phase deviation, α for the synchronizing frequency component ₂The phase deviation, the α that cause at model frequency for low pass filter ₃The time delay, the α that cause for measurement ₄Be the time delay that power electronic equipment may cause, ω _pFrequency for current sub-synchronous oscillation.

The present invention proposes a kind of for the antihunt system that suppresses sub-synchronous oscillation, and the control method of this system is provided.Compare with existing method, antihunt provided by the invention suppresses system and control method does not need the origin cause of formation, process and waveform composition to the sub-synchronous oscillation complexity to do labor, control principle is more clear, also all be easy to Project Realization specific to each control module, stronger practicality is arranged.Antihunt inhibition system and control method are controlled simply in actual applications, and be easy for installation, fast, is easy to Project Realization flexibly.

Description of drawings

By reading the detailed description of non-limiting example being done with reference to the following drawings, it is more obvious that other features, objects and advantages of the present invention will become:

Fig. 1 inserts the structural representation of electrical system for antihunt inhibition system among the present invention;

Fig. 2 is the system construction drawing of l-G simulation test in the embodiment of the invention;

Fig. 3 is system's shafting torsional oscillation waveform of introducing in the embodiment of the invention before antihunt suppresses system;

Fig. 4 is the system's shafting torsional oscillation waveform after the introducing antihunt inhibition system in the embodiment of the invention.

Embodiment

The present invention is described in detail below in conjunction with specific embodiment.Following examples will help those skilled in the art further to understand the present invention, but not limit the present invention in any form.Should be pointed out that to those skilled in the art, without departing from the inventive concept of the premise, can also make some distortion and improvement.These all belong to protection scope of the present invention.

As shown in Figure 1, the measurement processor 1, inverting amplifier 2, low pass filter 3, phase compensator 4, the power signal generating means 5 that comprise the torsional mode signal that links to each other successively according to antihunt inhibition provided by the invention system.The torsional mode component of from steam turbine and generator, gathering, input to measurement processor 1, the signal input inversion amplifier 2 of measurement processor 1 output, signal input low pass filter 3 after inverting amplifier 2 anti-phase amplifications, signal input phase compensator 4 after low pass filter 3 filtering High-frequency Interference, signal input power signal generating means 5 after phase compensator 4 compensation, 5 pairs of systems of power signal generating means output reactive current, the increase system effectively suppresses sub-synchronous oscillation to the electrical damping of sub-synchronous oscillation.

Described measurement processor 1 is made of its transfer function H a first order inertial loop ₁(s) be:

$H_1\left(s\right)=\frac{1}{1+s{T}_1}$ Formula 1

In the formula, T ₁Be time constant.

Because the generator speed deviation signal is lower to the phase shift susceptibility of controller, gets final product so generally get the speed error signal of generator.Sometimes also can use machine end power output as measuring object.

Described inverting amplifier 2 carries out anti-phase amplification with the signal after the measurement links, and with the sub-synchronous oscillation electric current in the inhibition system, its amplification coefficient is K.This amplification coefficient needs to adjust according to actual conditions, and the too for a short time purpose that does not reach effective inhibition sub-synchronous oscillation can influence the normal operation of system too greatly again.

Described low pass filter 3, the elimination high-frequency interferencing signal adopts second-order low-pass filter here, its transfer function H ₂(s) be:

$H_2\left(s\right)\frac{{\mathrm{<figure-callout\; id="0"\; label="G"\; filenames="HSA00000883392500021.png"\; state="\{\{state\}\}">G</figure-callout>}}_0{{\mathrm{\&omega;}}_n}^2}{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="HSA00000883392500021.png"\; state="\{\{state\}\}">s</figure-callout>}}^2+\mathrm{\&xi;}{\mathrm{\&omega;}}_{n}s+{{\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HSA00000883392500021.png"\; state="\{\{state\}\}">n</figure-callout>}}}^2}$ Formula 2

In the formula, G ₀Be the logical gain of band of low pass filter, ω _nBe natural angular frequency, ξ is the damping coefficient of filter.

Described phase compensator 4 is to design at the delay in filtering, the measurement links, and power electronic equipment also can cause some delays in addition.Phase compensator 4 can adopt the all-pass digital filter series connection to compensate.Its advantage is that amplitude-frequency characteristic does not change signal amplitude to all frequencies, only carries out phase compensation.Its transfer function H (s) is: $H\left(s\right)=\frac{s-c}{s+\mathrm{<figure-callout\; id="3"\; label="c\; Formula"\; filenames="HSA00000883392500021.png"\; state="\{\{state\}\}">c</figure-callout>}}$ Formula 3

During the designed phase compensation tache, consider the phase deviation α of each subsynchronous frequency component ₁, the phase deviation α that causes at model frequency of low pass filter ₂, measure the time delay α cause ₃, and the power electronic equipment time delay α that may cause ₄Then the value of c is determined by following formula.

Formula 4

In the formula, ω _pFrequency for current sub-synchronous oscillation.

Described power signal generating means 5 is a kind of devices that can send controlled reactive current to system.Reactive current input oscillatory system is eliminated subsynchronous component, and the increase system is to the electrical damping of sub-synchronous oscillation.

Because the sub-synchronous oscillation test is a destructive testing for large-scale unit, so be difficult for carrying out, sub-synchronous oscillation second model that will provide IEEE in Matlab/Simulink below carries out the l-G simulation test of present embodiment.As shown in Figure 2, the parameter of this system: generator: 600MVA, 22kV; Main step-up transformer: 22kV/500Kv; String benefit degree: 55%; Infinite bus system: 3333MVA, 500kV.Experiment back 4/3 cycle of beginning, circuit generation three phase short circuit fault, be 0.0169s fault time.

System's string benefit degree is 55% o'clock, and the resonance frequency of electrical system is 44.53Hz, with the torsion frequency 15.54Hz complementation (in the emulation, system's power frequency is 60Hz) of steam turbine.As seen from Figure 3, after fault took place, the axle of unit was that torque oscillation increases, and the sub-synchronous oscillation phenomenon has taken place.Fault takes place after the 8s, and generator and low pressure (LP) cylinder countershaft are that moment of torsion has reached 17p.u, and low pressure (LP) cylinder and high pressure cylinder countershaft are that moment of torsion has reached 7p.u.

Adopt antihunt inhibition system and control method in the present embodiment that this sub-synchronous oscillation is suppressed.As seen from Figure 4, added after the antihunt inhibition system, system's axle is that moment of torsion is decayed fast.Fault takes place after the 8s, and generator and low pressure (LP) cylinder countershaft are that moment of torsion has dropped to below the 0.5p.u, and low pressure (LP) cylinder and high pressure cylinder countershaft are that moment of torsion has dropped to below the 0.25p.u.

By explanation and the checking of present embodiment, as seen, after the introducing antihunt suppressed system and control method thereof, the sub-synchronous oscillation of system was effectively suppressed, and the moment of torsion between axle system of system is reduced greatly.

More than specific embodiments of the invention are described.It will be appreciated that the present invention is not limited to above-mentioned specific implementations, those skilled in the art can make various distortion or modification within the scope of the claims, and this does not influence flesh and blood of the present invention.

Claims (10)

1. the antihunt of a Generator Set sub-synchronous oscillation suppresses system, it is characterized in that, comprises as lower device:

Measurement processor for the torsional mode component signal of measuring prime mover, is exported to inverting amplifier with the torsional mode component signal then;

Inverting amplifier is used for described torsional mode component is carried out anti-phase amplification, makes the signal after the anti-phase amplification can control power electronic equipment output grid power rank electric current, then the signal after the described anti-phase amplification is exported to low pass filter;

Low pass filter is used for the high-frequency signal that the signal after the described anti-phase amplification of filtering disturbs, then with filtered signal input phase compensator;

Phase compensator is used for described filtered signal is compensated because of the phase delay that electrical system and described measurement processor and low pass filter cause, then the signal after the phase compensation is exported to the power signal generating means;

The power signal generating means is converted into the signal of power stage with the signal after the described phase compensation, exports to electrical system, increases electrical system to the electrical damping of sub-synchronous oscillation, eliminates the subsynchronous component in the electrical system, suppresses sub-synchronous oscillation.

2. the antihunt of Generator Set sub-synchronous oscillation according to claim 1 suppresses system, it is characterized in that, described torsional mode component is the signal that can reflect the sub-synchronous oscillation characteristic, the described signal of sub-synchronous oscillation characteristic that can reflect comprises generator speed deviation, machine end power output or high pressure cylinder rotating speed deviation, described low pass filter is used for the signal after the described anti-phase amplification is higher than the whole filterings of interference signal of power frequency.

3. the antihunt of Generator Set sub-synchronous oscillation according to claim 1 suppresses system, it is characterized in that described measurement processor mainly is made of the transfer function H of described measurement processor a first order inertial loop ₁(s) be:

$H_1\left(s\right)=\frac{1}{1+s{T}_1}$ Formula 1

In the formula 1, T ₁Be time constant.

4. the antihunt of Generator Set sub-synchronous oscillation according to claim 1 suppresses system, it is characterized in that, described low pass filter adopts second-order low-pass filter, the transfer function H of described low pass filter ₂(s) be:

$H_2\left(s\right)\frac{G_0{{\mathrm{\&omega;}}_n}^2}{s^2+\mathrm{\&xi;}{\mathrm{\&omega;}}_{n}s+{{\mathrm{\&omega;}}_n}^2}$ Formula 2

In the formula 2, G ₀Be the logical gain of band of low pass filter, ω _nBe natural angular frequency, ξ is the damping coefficient of filter.

5. the antihunt of Generator Set sub-synchronous oscillation according to claim 1 suppresses system, it is characterized in that the transfer function H of described phase compensator (s) is:

$H\left(s\right)=\frac{s-c}{s+c}$ Formula 3

In the formula 3, the value of parameter c is by determining with following formula 4:

Formula 4

In the formula 4, α ₁Phase deviation, α for the synchronizing frequency component ₂The phase deviation, the α that cause at model frequency for low pass filter ₃The time delay, the α that cause for measurement ₄Be the time delay that power electronic equipment may cause, ω _pFrequency for current sub-synchronous oscillation.

6. the antihunt inhibition method of a Generator Set sub-synchronous oscillation is characterized in that, comprises the steps

Step 1: the torsional mode component signal of measuring prime mover;

Step 2: the anti-phase amplification of described torsional mode component that will measure makes the signal after the anti-phase amplification can control power electronic equipment output grid power rank electric current;

Step 3: the high-frequency signal that disturbs in the signal after the described anti-phase amplification of filtering;

Step 4: the phase delay that causes because of electrical system and described measurement processor and low pass filter in the described filtered signal is compensated;

Step 5: the signal after the described phase compensation is converted into the signal of power stage, exports to electrical system, eliminate the subsynchronous component in the electrical system, suppress sub-synchronous oscillation, increase electrical system to the electrical damping of sub-synchronous oscillation.

7. the antihunt inhibition method of Generator Set sub-synchronous oscillation according to claim 6, it is characterized in that, described torsional mode component is the signal that can reflect the sub-synchronous oscillation characteristic, the described signal of sub-synchronous oscillation characteristic that can reflect comprises generator speed deviation, machine end power output or high pressure cylinder rotating speed deviation, in described step 3, since all frequencies of oscillation in the sub-synchronous oscillation all at 10 hertz between the power frequency, so in the inhibition of sub-synchronous oscillation, do following processing:

-all are higher than all filterings of interference signal of power frequency; Perhaps

In-actual the engineering, disturb if power frequency component produces control system, then power frequency is also contained in the filtering scope of low pass filter, or increases the band stop filter of power frequency in addition.

8. the antihunt inhibition method of Generator Set sub-synchronous oscillation according to claim 6 is characterized in that, described step 1, particularly, utilize measurement processor to realize, wherein, described measurement processor mainly is made of a first order inertial loop, the transfer function H of described measurement processor ₁(s) be:

$H_1\left(s\right)=\frac{1}{1+s{T}_1}$ Formula 1

In the formula 1, T ₁Be time constant.

9. the antihunt inhibition method of Generator Set sub-synchronous oscillation according to claim 6, it is characterized in that, in described step 3 since sub-synchronous oscillation in all frequencies of oscillation all at 10 hertz between the power frequency, so in the inhibition of sub-synchronous oscillation, do following processing:

-all are higher than all filterings of interference signal of power frequency; Perhaps

In-actual the engineering, disturb if power frequency component produces control system, then power frequency be also contained in the filtering scope of low pass filter, or increase the band stop filter of power frequency in addition,

Particularly, utilize low pass filter to realize, wherein, described low pass filter adopts second-order low-pass filter, the transfer function H of described low pass filter ₂(s) be:

$H_2\left(s\right)\frac{G_0{{\mathrm{\&omega;}}_n}^2}{s^2+\mathrm{\&xi;}{\mathrm{\&omega;}}_{n}s+{{\mathrm{\&omega;}}_n}^2}$ Formula 2

In the formula 2, G ₀Be the logical gain of band of low pass filter, ω _nBe natural angular frequency, ξ is the damping coefficient of filter.

10. the antihunt inhibition method of Generator Set sub-synchronous oscillation according to claim 6, it is characterized in that, described step 4, measurement in the abovementioned steps, filtering link and power electronic equipment are brought compensating of delay, in the practical application, by increase suitable leading-delay component, the angle of these delays is reduced to below 10 °

Particularly, utilize phase compensator to realize that the transfer function H of described phase compensator (s) is:

$H\left(s\right)=\frac{s-c}{s+c}$ Formula 3

In the formula 3, the value of parameter c is by determining with following formula 4:

Formula 4

In the formula 4, α ₁Phase deviation, α for the synchronizing frequency component ₂The phase deviation, the α that cause at model frequency for low pass filter ₃The time delay, the α that cause for measurement ₄Be the time delay that power electronic equipment may cause, ω _pFrequency for current sub-synchronous oscillation.

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