CN110323746B - Method and system for detecting stability of dissipated energy of direct-drive permanent magnet wind power system - Google Patents

Method and system for detecting stability of dissipated energy of direct-drive permanent magnet wind power system Download PDF

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CN110323746B
CN110323746B CN201910694971.3A CN201910694971A CN110323746B CN 110323746 B CN110323746 B CN 110323746B CN 201910694971 A CN201910694971 A CN 201910694971A CN 110323746 B CN110323746 B CN 110323746B
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马静
周晓东
李沛
汪乐天
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North China Electric Power University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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Abstract

The invention relates to a method and a system for detecting the stability of dissipated energy of a direct-drive permanent magnet wind power system, and belongs to the technical field of wind power generation. The method comprises the following steps: s1, acquiring the operation data of the direct-drive permanent magnet wind power system; s2, calculating the dissipated energy of the direct-drive permanent magnet wind power system according to the operation data; and S3, performing stability detection on the system according to the dissipated energy of the direct-drive permanent magnet wind power system. According to the method, a wind power system dissipated energy model of the links of grid-side converter phase-locked loop control, current loop control and parallel SVG control is constructed, stability detection is carried out on the direct-drive wind power system based on the dissipated energy model, and real-time detection of the stability of the wind power grid-connected system is achieved.

Description

Method and system for detecting stability of dissipated energy of direct-drive permanent magnet wind power system
Technical Field
The invention relates to the technical field of wind power generation, in particular to a method and a system for detecting the stability of dissipated energy of a direct-drive permanent magnet wind power system.
Background
With the increase of double pressure of energy crisis and environmental pollution, the conventional power supply is largely replaced by wind power. On one hand, the wind turbine generator continuously weakens the system inertia and damping level; on the other hand, due to the rapid response characteristic of the power electronic converter, the wind turbine generator is mutually coupled with the power grid, and a new broadband stability problem is caused. This allows multiple subsynchronous oscillation events to occur in the power system. Therefore, intensive research on the generation mechanism of the subsynchronous oscillation is required.
At present, the analysis of the dynamic characteristics of the subsynchronous oscillation of the wind power grid-connected system has gradually become a research hotspot of numerous experts and scholars at home and abroad. However, the deconstruction and control of the wind turbine generator are different, and the oscillation process presents the characteristics of uncertainty and diversified forms, so that the existing time domain simulation analysis method is difficult to perform stability detection on the wind power grid-connected system in real time.
Disclosure of Invention
In view of the above analysis, the invention aims to provide a method and a system for detecting the stability of dissipated energy of a direct-drive permanent magnet wind power system, so as to solve the problem that the stability of a wind power grid-connected system is difficult to detect in real time by the prior art.
The purpose of the invention is mainly realized by the following technical scheme:
on one hand, the invention provides a method for detecting the stability of dissipated energy of a direct-drive permanent magnet wind power system, which comprises the following steps: s1, acquiring the operation data of the direct-drive permanent magnet wind power system; s2, calculating the dissipated energy of the direct-drive permanent magnet wind power system according to the operation data; and S3, performing stability detection on the system according to the dissipated energy of the direct-drive permanent magnet wind power system.
Further, the operation data of the system in step S1 includes the fundamental frequency, the subsynchronous component, the voltage or current amplitude of the supersynchronous component, the angular frequency, the initial phase angle, and the electrical angular velocity of the generator.
Further, in the step S2, the direct-drive permanent magnet wind power system dissipates energy WHSDissipating energy W for a phase locked loopHS1Sum current loop dissipated energy WHS2The formula is as follows:
WHS＝WHS1+WHS2
Figure BDA0002149082920000021
Figure BDA0002149082920000022
wherein U is a voltage, I is a current, X is a voltage or a current, X0、ω0、
Figure BDA0002149082920000023
Respectively, the amplitude, angular frequency, initial phase angle, X, of the fundamental voltage or current_、
Figure BDA0002149082920000024
Amplitude, initial phase angle, X, of subsynchronous component voltage or current, respectively+、
Figure BDA0002149082920000025
Amplitude, initial phase angle, omega, of the supersynchronous component voltage or current, respectivelysIs the electrical angular velocity of the generator.
Further, the stability detection of the system according to the power dissipation energy of the direct-drive permanent magnet wind power comprises the following steps:
when W isHSWhen the frequency is more than 0, the direct-drive fan continuously emits dissipation energy in the subsynchronous oscillation process, the oscillation has a negative damping characteristic, the transient energy imported into a power grid is continuously increased, and the oscillation divergence instability is induced;
when W isHSWhen the frequency is less than 0, the direct-drive fan absorbs the dissipated energy in the subsynchronous oscillation process, the oscillation is represented as a positive damping characteristic, the transient energy converged into the power grid is gradually reduced, and the oscillation is finally converged;
when W isHSWhen being equal to 0, the direct-drive fan does not emit and does not absorb the dissipated energy, the oscillation is represented by the undamped characteristic, and the system is in constant-amplitude oscillation.
On the other hand, the system for detecting the stability of the dissipated energy of the direct-drive permanent magnet wind power system comprises a data acquisition module, a dissipated energy calculation module, a stability detection module and a result output module; the data acquisition module is used for acquiring the operating data of the direct-drive permanent magnet wind power system; the dissipated energy calculating module is used for calculating the dissipated energy of the direct-drive permanent magnet wind power system according to a dissipated energy model and the operation data output by the data acquisition module; the stability detection module is used for carrying out stability detection on the system according to the dissipated energy of the direct-drive permanent magnet wind power system; and the result output module is used for outputting the system dissipated energy and the corresponding system stability detection result.
Further, the operation data collected by the data collection module comprises a fundamental frequency, a subsynchronous component, a voltage or current amplitude value of a supersynchronous component, an angular frequency, an initial phase angle and an electrical angular velocity of the generator.
Further, the calculation formula of the dissipated energy model in the dissipated energy solving module is as follows:
WHS＝WHS1+WHS2
Figure BDA0002149082920000031
Figure BDA0002149082920000032
wherein U is a voltage, I is a current, X is a voltage or a current, X0、ω0、
Figure BDA0002149082920000033
Respectively, the amplitude, angular frequency, initial phase angle, X, of the fundamental voltage or current-、
Figure BDA0002149082920000034
Amplitude, initial phase angle, X, of subsynchronous component voltage or current, respectively+、
Figure BDA0002149082920000035
Amplitude, initial phase angle, omega, of the supersynchronous component voltage or current, respectivelysIs the electrical angular velocity of the generator.
Further, the stability detection module performing stability detection on the dissipated energy calculated by the dissipated energy model includes:
when W isHSWhen the frequency is more than 0, the direct-drive fan continuously emits dissipation energy in the subsynchronous oscillation process, the oscillation has a negative damping characteristic, the transient energy imported into a power grid is continuously increased, and the oscillation divergence instability is induced;
when W isHSWhen the frequency is less than 0, the direct-drive fan absorbs the dissipated energy in the subsynchronous oscillation process, the oscillation is represented as a positive damping characteristic, the transient energy converged into the power grid is gradually reduced, and the oscillation is finally converged;
when W isHSWhen being equal to 0, the direct-drive fan does not emit and does not absorb the dissipated energy, the oscillation is represented by the undamped characteristic, and the system is in constant-amplitude oscillation.
Further, the system stability detection result output by the result output module includes oscillation divergence, oscillation convergence and constant amplitude oscillation.
Furthermore, an input port of the data acquisition module is connected with a data output port of the direct-drive permanent magnet wind power system, an output port of the data acquisition module is connected with an input port of the dissipated energy calculation module, an output port of the dissipated energy calculation module is connected with an input port of the stability detection module, and an output port of the stability detection module is connected with an input port of the result output module.
The beneficial effects of the technical scheme are as follows: the invention discloses a method and a system for detecting the stability of dissipated energy of a direct-drive permanent magnet wind power system, wherein a wind power system dissipated energy model in the links of grid-outlet side converter phase-locked loop control, current loop control and parallel SVG control is constructed, and the stability of the direct-drive wind power system is detected based on the dissipated energy model, so that the real-time detection of the stability of the wind power grid-connected system is realized, the stability of the direct-drive wind power system is detected more comprehensively and accurately, and the stability can be effectively controlled.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
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The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
FIG. 1 is a flow chart of a method for detecting stability of dissipated energy of a direct-drive permanent magnet wind power system according to an embodiment of the invention;
FIG. 2 is a structural diagram of a direct-drive wind turbine generator set according to an embodiment of the invention;
FIG. 3 is a model of a permanent magnet synchronous generator according to an embodiment of the present invention;
fig. 4 is a structural diagram of a direct-drive fan grid-connected system according to an embodiment of the invention;
FIG. 5 is a graph of the oscillation divergence active power of the direct drive fan according to the embodiment of the present invention;
FIG. 6 is a frequency spectrum diagram of a direct-drive fan oscillating divergence outlet current according to an embodiment of the present invention;
FIG. 7 illustrates transient state energy and dissipated energy at a direct drive fan oscillation dissipating port according to an embodiment of the present invention;
FIG. 8 is a direct drive fan oscillation divergence transient energy and active power spectrum of an embodiment of the present invention;
FIG. 9 is a graph of the constant amplitude oscillation active power of the direct-drive fan according to the embodiment of the present invention;
FIG. 10 illustrates transient state energy and dissipation energy of a constant amplitude oscillation port of a direct-drive wind turbine according to an embodiment of the present invention;
FIG. 11 is a direct drive fan oscillation convergence active power curve diagram according to an embodiment of the invention;
fig. 12 shows transient energy and dissipated energy at the oscillation convergence port of the direct-drive wind turbine according to the embodiment of the invention.
Detailed Description
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate preferred embodiments of the invention and together with the description, serve to explain the principles of the invention and not to limit the scope of the invention.
One specific embodiment of the invention, as shown in fig. 1, discloses a method for detecting the stability of dissipated energy of a direct-drive permanent magnet wind power system, comprising the following steps:
s1, acquiring the operation data of the direct-drive permanent magnet wind power system;
s2, calculating the dissipated energy of the direct-drive permanent magnet wind power system according to the operation data;
and S3, performing stability detection on the system according to the dissipated energy of the direct-drive permanent magnet wind power system.
According to the method, the stability of the direct-drive permanent magnet wind power grid-connected system is detected by calculating the dissipated energy of the direct-drive permanent magnet wind power system, so that the real-time detection of the stability of the wind power grid-connected system is realized, and the stability of the system is detected more comprehensively and accurately.
In an embodiment of the present invention, the operation data of the system in step S1 includes the fundamental frequency, the subsynchronous component, the voltage or current amplitude of the supersynchronous component, the angular frequency, the initial phase angle, and the electrical angular velocity of the generator.
In an embodiment of the invention, the step S2 is a direct-drive permanent magnetWind power system dissipated energy WHSDissipating energy W for a phase locked loopHS1Sum current loop dissipated energy WHS2The formula is as follows:
WHS＝WHS1+WHS2
Figure BDA0002149082920000061
Figure BDA0002149082920000062
wherein U is a voltage, I is a current, X is a voltage or a current, X0、ω0、
Figure BDA0002149082920000063
Respectively, the amplitude, angular frequency, initial phase angle, X, of the fundamental voltage or current-、
Figure BDA0002149082920000064
Amplitude, initial phase angle, X, of subsynchronous component voltage or current, respectively+、
Figure BDA0002149082920000065
Amplitude, initial phase angle, omega, of the supersynchronous component voltage or current, respectivelysIs the electrical angular velocity of the generator.
It should be noted that, in order to obtain the dissipated energy of the direct-drive permanent magnet wind power system, a system transient energy model needs to be constructed first, and then a non-periodic component in the transient energy model is integrated to obtain the dissipated energy model, which includes the following specific processes:
the transient energy function of the direct-drive permanent magnet wind turbine generator is expressed as follows:
WPMSG＝∫(i2ddu2q-i2qdu2d)+∫(i2du2d+i2qu2q)d2＝WPMSG1+WPMSG2
in the formula: u. of2d、u2q、i2d、i2qThe d-axis component and the q-axis component of the voltage and the current of the grid-side converter are respectively,2is the power angle of the fan outlet.
As shown in fig. 2, the direct-drive wind turbine generator set is composed of a fan, a permanent magnet synchronous generator, a machine side converter, a direct current link and a grid side converter.
The direct current link only transmits active power, and the existence of the direct current capacitor ensures the stability of direct current voltage to a certain extent, but when disturbance exists in a system or the wind power changes greatly, the active power on two sides of the direct current capacitor cannot be completely consistent in the transient process. Neglecting the losses of the converter, the energy conservation can be obtained:
Figure BDA0002149082920000071
in the formula: u. of1d、u1q、i1d、i1qD-and q-axis components, u, of the voltage and current, respectively, of the machine side converter2d、u2q、i2d、i2qD-axis components and q-axis components of voltage and current of the grid-side converter respectively, C is a capacitor, and u isdcIs the dc side voltage.
Then, from the above equation:
Figure BDA0002149082920000072
in the formula: u. of1d、u1q、i1d、i1qD-and q-axis components, u, of the voltage and current, respectively, of the machine side converter2d、u2q、i2d、i2qD-axis components and q-axis components of voltage and current of the grid-side converter respectively, C is a capacitor, and u isdcIs a DC side voltage, omega2Is the electrical angular velocity of the power grid.
Because the reference values of the machine side rotating speed control and the network side system frequency regulation are consistent, the change of the electrical angular speed in the transient process is not large, namely omega1≈ω2Then, there are:
WPMSG2＝∫P1d1+∫Cω2udcdudc
in the formula: p1＝id1ud1+iq1uq1For the output of the permanent magnet synchronous generator to work, see the permanent magnet synchronous generator model shown in fig. 3,1is the power angle, omega, of the permanent magnet synchronous generator2For electric angular velocity, U, of the griddcIs a dc voltage.
The transient energy function of the direct-drive permanent magnet wind turbine generator can be expressed as follows:
WPMSG＝∫(i2ddu2q-i2qdu2d)+∫P1d1+∫Cω2udcdudc
in the formula: u. of2d、u2q、i2d、i2qD-and q-axis components of the voltage and current, P, respectively, of the grid-side converter1＝id1ud1+iq1uq1For the output of the permanent magnet synchronous generator to work, see the permanent magnet synchronous generator model shown in fig. 3,1is the power angle, omega, of the permanent magnet synchronous generator2For electric angular velocity, U, of the griddcIs a dc voltage.
The transient energy consists of three parts, which are respectively: controlled independently by grid-side converter and influenced by grid disturbance [ integral ] of2ddu2q-i2qdu2d) A moiety; integral multiple P controlled by receiver side converter and permanent magnet generator and influenced by wind power1d1A moiety; controlled by network side converter and influenced by receiver side converter2udcdudcAnd (4) partial.
Transient energy of the element comprises two parts, wherein one part is a conservative item irrelevant to a path, and corresponds to a period variable quantity, and the energy of the part also oscillates in the oscillation process, so that the characteristic of the element is not beneficial to analysis; some are non-conservative with respect to the path, are monotonic during oscillation, and dissipate energy.
The direct-drive fan participates in the field wave recording analysis of subsynchronous oscillation, subsynchronous frequency and supersynchronous frequency tend to appear in pairs, and the assumed instantaneous values of three-phase voltage and current consist of fundamental wave and a pair of subsynchronous frequency components with complementary frequencies, which can be expressed as follows:
Figure BDA0002149082920000081
wherein x is a voltage or a current; x is the number ofa、xb、xcInstantaneous values of three-phase voltages or currents; x0、ω0、
Figure BDA0002149082920000082
The amplitude, angular frequency and initial phase angle of the fundamental frequency voltage or current respectively; x-、ω-、
Figure BDA0002149082920000083
The amplitude, angular frequency and initial phase angle of the subsynchronous component voltage or current are respectively; x+、ω+、
Figure BDA0002149082920000084
The amplitude, angular frequency and initial phase angle of the supersynchronous component voltage or current are respectively.
Calculating the transient state dissipated energy, firstly converting the voltage and the current from the abc stationary coordinate system to the dq coordinate system rotating at the rated electrical angular speed, and taking the voltage and the current
Figure BDA0002149082920000085
And memorize: omegas＝ω0-ω-＝ω+-ω0Obtaining the d-axis component expression and the q-axis component expression of the voltage and the current as follows:
Figure BDA0002149082920000091
Figure BDA0002149082920000092
and obtaining the deformation of the transient energy expression by the d-axis component expression and the q-axis component expression of the voltage and the current:
WPMSG1＝∫(i2du′2q-i2qu′2d)dt
WPMSG2＝∫(i2du2d+i2qu2q)ω2dt
in the formula: u. of2′d,u2′qThe derivatives of the d and q axis components of the voltage, respectively.
The dissipated energy is the integral of the non-periodic component in the transient energy expression, and (i) is reserved2du2d+i2qu2q) The non-periodic component, ω, in the expression2The non-periodic component in (1) is approximated by ω0To obtain WPMSG2In the medium ofHS2The expression is as follows:
Figure BDA0002149082920000093
since the amplitude and phase of each frequency component are time-varying, it is necessary to correct u2d、u2qPartial derivation:
Figure BDA0002149082920000094
u's'2d、u′2q、i2d、i2qSubstituting the expression of (2) into WPMSG1And keeping the non-periodic term in the integration to obtain WPMSG1In the medium ofHS1The expression is as follows:
Figure BDA0002149082920000095
according to a specific embodiment of the invention, the stability detection of the system according to the power dissipation energy of the direct-drive permanent magnet wind power comprises the following steps:
when W isHSWhen the frequency is more than 0, the direct-drive fan continuously emits dissipation energy in the subsynchronous oscillation process, the oscillation has a negative damping characteristic, the transient energy imported into a power grid is continuously increased, and the oscillation divergence instability is induced;
when W isHSWhen the frequency is less than 0, the direct-drive fan absorbs the dissipated energy in the subsynchronous oscillation process, the oscillation is represented as a positive damping characteristic, the transient energy converged into the power grid is gradually reduced, and the oscillation is finally converged;
when W isHSWhen being equal to 0, the direct-drive fan does not emit and does not absorb the dissipated energy, the oscillation is represented by the undamped characteristic, and the system is in constant-amplitude oscillation.
According to a specific embodiment of the invention, the system for detecting the stability of the dissipated energy of the direct-drive permanent magnet wind power system comprises a data acquisition module, a dissipated energy calculation module, a stability detection module and a result output module;
the data acquisition module is used for acquiring the operating data of the direct-drive permanent magnet wind power system;
the dissipated energy calculating module is used for calculating the dissipated energy of the direct-drive permanent magnet wind power system according to a dissipated energy model and the operation data output by the data acquisition module;
the stability detection module is used for carrying out stability detection on the system according to the dissipated energy of the direct-drive permanent magnet wind power system;
and the result output module is used for outputting the system dissipated energy and the corresponding system stability detection result.
It should be noted that, in order to achieve the purpose of the present invention, a system for detecting the stability of dissipated energy of a direct-drive permanent magnet wind power system is provided, which includes the following modules connected in sequence: the device comprises a data acquisition module, a dissipated energy calculation module, a stability detection module and a result output module. The data acquisition module is used for acquiring system data and transmitting the system data to the dissipated energy calculation module. The dissipated energy calculating module receives the data transmitted by the data acquisition module and calculates the dissipated energy of the wind power system. And the stability detection module is used for detecting the stability of the wind power system according to the calculation result of the dissipated energy calculation module. And the result output module is used for outputting the system dissipation energy and the stability detection result.
In an embodiment of the present invention, the operation data collected by the data collection module includes a fundamental frequency, a sub-synchronous component, a voltage or current amplitude, an angular frequency, an initial phase angle of a super-synchronous component, and an electrical angular velocity of the generator. That is, the present embodiment provides sufficient data for the dissipated energy model through a data acquisition module to calculate the dissipated energy of the system.
In an embodiment of the present invention, the calculation formula of the dissipated energy model in the dissipated energy calculation module is as follows:
WHS＝WHS1+WHS2
Figure BDA0002149082920000111
Figure BDA0002149082920000112
wherein U is a voltage, I is a current, X is a voltage or a current, X0、ω0、
Figure BDA0002149082920000113
Respectively, the amplitude, angular frequency, initial phase angle, X, of the fundamental voltage or current-、
Figure BDA0002149082920000114
Amplitude, initial phase angle, X, of subsynchronous component voltage or current, respectively+、
Figure BDA0002149082920000115
Amplitude, initial phase angle, omega, of the supersynchronous component voltage or current, respectivelysIs the electrical angular velocity of the generator.
In an embodiment of the present invention, the stability detecting module performing stability detection on the dissipated energy calculated by the dissipated energy model includes:
when W isHSWhen the frequency is more than 0, the direct-drive fan continuously emits dissipation energy in the subsynchronous oscillation process, the oscillation has a negative damping characteristic, the transient energy imported into a power grid is continuously increased, and the oscillation divergence instability is induced;
when W isHSWhen the air pressure is less than 0, the fan is directly drivenThe energy is dissipated in the subsynchronous oscillation process, the oscillation is represented as positive damping characteristic, the transient energy which is imported into the power grid is gradually reduced, and the oscillation is finally converged;
when W isHSWhen being equal to 0, the direct-drive fan does not emit and does not absorb the dissipated energy, the oscillation is represented by the undamped characteristic, and the system is in constant-amplitude oscillation.
In practical application, as shown in fig. 4, for example, the direct-drive fan grid-connected system calculates transient energy and dissipation energy of a direct-drive fan grid-connected measurement point under different working conditions of the system, performs stability detection on the direct-drive fan grid-connected system, and verifies the correctness of a result.
The rated capacity of the fan is 1MW, and the fan passes through a transformer in a 0.69/20kV field and is connected to a PCC point through an 20/230kV transformer. The parameters of the direct drive fan are shown in table 1.
TABLE 1 direct drive Fan parameters
Figure BDA0002149082920000121
The equivalent resistance and reactance of the network side converter incoming line reactor are as follows: rT＝0.0160p.u，LT0.0004 p.u; the equivalent impedance of the power grid is 0.4 mH; rated value U of DC voltagedc1200V; the dc capacitance C is 14000 μ F.
In an embodiment of the invention, the system stability detection result output by the result output module includes oscillation divergence, oscillation convergence and constant amplitude oscillation. The concrete description is as follows:
(1) system oscillation divergence
When t is set to be 0.5s, the system is disturbed to cause subsynchronous oscillation, an active power curve output by the direct-drive fan is shown in fig. 5, fig. 6 is a current frequency spectrum, and the oscillation frequency is 28Hz/72 Hz. The transient energy and dissipation energy results of the port of the direct-drive fan obtained through calculation at this time are shown in fig. 7, and the transient energy spectrum and the active power spectrum are compared and shown in fig. 8.
As can be seen from FIG. 8, the frequency of the harmonic component in the active power and the transient energy of the direct-drive wind turbine is 22Hz, which is complementary to the subsynchronous current frequency about the fundamental frequency. The transient energy of the direct-drive fan still contains partial periodic components, is close to the subsynchronous frequency harmonic amplitude in active power and is mainly a coupling term of fundamental frequency components and subsynchronous components, so that the direct-current components, namely non-periodic components in the transient energy can intuitively reflect the development rule of oscillation.
Comparing fig. 5 and fig. 7, it can be seen that when the direct-driven fan subsynchronous oscillation is dispersed and destabilized, the calculated fan port transient energy curve has a similar trend to the active power curve, the oscillation and amplitude are continuously increased, the dissipated energy of the fan port is positive, and the slope is unchanged, so that the fan continuously provides oscillation energy to the system in the subsynchronous oscillation process, which results in dispersion destabilization.
(2) System constant amplitude oscillation
When t is set to be 0.5s, the system disturbance causes subsynchronous/supersynchronous oscillation with equal amplitude, an active power curve output by the direct-drive fan is shown in fig. 9, a port transient energy and dissipation energy result obtained through calculation is shown in fig. 10, and the transient energy spectrum is the same as the oscillation divergence condition.
When ideal equal-amplitude subsynchronous oscillation is carried out, the direct-drive fan does not emit energy or absorb energy in the transient process, but a certain positive damping or negative damping effect is achieved in the subsynchronous oscillation process due to the existence of the impedance element in an actual system, and the direct-drive fan and the converter incoming line reactor and the line impedance have zero damping characteristics on oscillation under the combined action. Therefore, the dissipation energy emitted by the direct-drive fan is not zero, in a sub/super synchronous scene where the section is located, the impedance element absorbs transient energy in the sub-synchronous oscillation process, but the transient energy absorbed by the impedance element is very limited, so that the port dissipation energy of the direct-drive fan is positive and has a small amplitude, and the transient energy of the port is increased by a small amplitude.
(3) System oscillation convergence
When t is set to be 0.5s, the system disturbance causes subsynchronous/supersynchronous oscillation, as shown in an active power curve output by the direct-drive fan in fig. 11, the oscillation is gradually converged, and the calculated port transient energy and dissipation energy results are shown in fig. 12.
It can be seen that when the subsynchronous oscillation gradually converges, the transient energy of the port of the direct-drive fan is continuously reduced but still greater than zero, which is due to the energy change in the transient process caused by the fundamental frequency component contained in the transient energy, and the direct-drive fan is a power supply, so that the energy of the transient-state port is positive. The dissipated energy is mainly affected by the magnitude of the subsynchronous/supersynchronous components, and the development of oscillation can be more intuitively reflected, as shown in fig. 12, if the dissipated energy at the fan port is negative, the fan absorbs the energy of the subsynchronous/supersynchronous oscillation and plays a positive damping role on the oscillation, which is consistent with the result of gradual convergence of the power oscillation in fig. 11.
According to a specific embodiment of the invention, an input port of the data acquisition module is connected with a data output port of the direct-drive permanent magnet wind power system, an output port of the data acquisition module is connected with an input port of the dissipated energy calculation module, an output port of the dissipated energy calculation module is connected with an input port of the stability detection module, and an output port of the stability detection module is connected with an input port of the result output module.
In summary, the invention discloses a method for detecting the stability of dissipated energy of a direct-drive permanent magnet wind power system, which comprises the following steps: s1, acquiring the operation data of the direct-drive permanent magnet wind power system; s2, calculating the dissipated energy of the direct-drive permanent magnet wind power system according to the operation data; and S3, performing stability detection on the system according to the dissipated energy of the direct-drive permanent magnet wind power system. Meanwhile, the system which forms the same inventive concept with the method is disclosed, and comprises a data acquisition module, a dissipated energy solving module, a stability detection module and a result output module; the data acquisition module is used for acquiring the operating data of the direct-drive permanent magnet wind power system; the dissipated energy calculating module is used for calculating the dissipated energy of the direct-drive permanent magnet wind power system according to a dissipated energy model and the operation data output by the data acquisition module; the stability detection module is used for carrying out stability detection on the system according to the dissipated energy of the direct-drive permanent magnet wind power system; and the result output module is used for outputting the stability detection result of the system. According to the technical scheme, a wind power system dissipation energy model of the network side converter phase-locked loop control, the current loop control and the parallel SVG control links is constructed, stability detection is carried out on the direct-drive wind power system based on the dissipation energy model, real-time detection of the stability of the wind power grid system is achieved, the stability of the direct-drive wind power system is detected more comprehensively and accurately, and the stability of the direct-drive wind power system can be effectively controlled.
Those skilled in the art will appreciate that all or part of the processes for implementing the methods in the above embodiments may be implemented by a computer program, which is stored in a computer-readable storage medium, to instruct associated hardware. The computer readable storage medium is a magnetic disk, an optical disk, a read-only memory or a random access memory.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims (8)

1. A method for detecting the stability of dissipated energy of a direct-drive permanent magnet wind power system is characterized by comprising the following steps:
s1, acquiring the operation data of the direct-drive permanent magnet wind power system;
s2, calculating the dissipated energy of the direct-drive permanent magnet wind power system according to the operation data;
dissipated energy W of direct-drive permanent magnet wind power systemHSDissipating energy W for a phase locked loopHS1Sum current loop dissipated energy WHS2The formula is as follows:
Figure FDA0002618582330000011
wherein U is a voltage, I is a current, X is a voltage or a current, X0、ω0、
Figure FDA0002618582330000012
Respectively, the amplitude, angular frequency, initial phase angle, X, of the fundamental voltage or current-、
Figure FDA0002618582330000013
Amplitude, initial phase angle, X, of subsynchronous component voltage or current, respectively+、
Figure FDA0002618582330000014
Amplitude, initial phase angle, omega, of the supersynchronous component voltage or current, respectivelysIs the electrical angular velocity of the generator;
and S3, performing stability detection on the system according to the dissipated energy of the direct-drive permanent magnet wind power system.
2. The method of claim 1, wherein the operation data of the system in step S1 includes the fundamental frequency, the subsynchronous component, the voltage or current amplitude of the supersynchronous component, the angular frequency, the initial phase angle, and the electrical angular velocity of the generator.
3. The method of claim 1, wherein the stability detection of the system according to the dissipated energy of the direct-drive permanent magnet wind power comprises:
when W isHSWhen the frequency is more than 0, the direct-drive fan continuously emits dissipation energy in the subsynchronous oscillation process, the oscillation has a negative damping characteristic, the transient energy imported into a power grid is continuously increased, and the oscillation divergence instability is induced;
when W isHSWhen the frequency is less than 0, the direct-drive fan absorbs the dissipated energy in the subsynchronous oscillation process, the oscillation is represented as a positive damping characteristic, the transient energy converged into the power grid is gradually reduced, and the oscillation is finally converged;
when W isHSWhen being equal to 0, the direct-drive fan does not emit and does not absorb the dissipated energy, the oscillation is represented by the undamped characteristic, and the system is in constant-amplitude oscillation.
4. A system for detecting the stability of dissipated energy of a direct-drive permanent magnet wind power system is characterized by comprising a data acquisition module, a dissipated energy calculation module, a stability detection module and a result output module;
the data acquisition module is used for acquiring the operating data of the direct-drive permanent magnet wind power system;
the dissipated energy calculating module is used for calculating the dissipated energy of the direct-drive permanent magnet wind power system according to a dissipated energy model and the operation data output by the data acquisition module;
the calculation formula of the dissipation energy model in the dissipation energy calculation module is as follows:
Figure FDA0002618582330000021
wherein U is a voltage, I is a current, X is a voltage or a current, X0、ω0、
Figure FDA0002618582330000022
Respectively, the amplitude, angular frequency, initial phase angle, X, of the fundamental voltage or current-、
Figure FDA0002618582330000023
Amplitude, initial phase angle, X, of subsynchronous component voltage or current, respectively+、
Figure FDA0002618582330000024
Amplitude, initial phase angle, omega, of the supersynchronous component voltage or current, respectivelysIs the electrical angular velocity of the generator; the stability detection module is used for carrying out stability detection on the system according to the dissipated energy of the direct-drive permanent magnet wind power system;
and the result output module is used for outputting the system dissipated energy and the corresponding system stability detection result.
5. The system of claim 4, wherein the operational data collected by the data collection module includes a fundamental frequency, a subsynchronous component, a voltage or current amplitude of a supersynchronous component, an angular frequency, an initial phase angle, and an electrical angular velocity of the generator.
6. The system of claim 4, wherein the stability detection module performing stability detection on the dissipated energy calculated by the dissipated energy model comprises:
when W isHSWhen the frequency is more than 0, the direct-drive fan continuously emits dissipation energy in the subsynchronous oscillation process, the oscillation has a negative damping characteristic, the transient energy imported into a power grid is continuously increased, and the oscillation divergence instability is induced;
when W isHSWhen the frequency is less than 0, the direct-drive fan absorbs the dissipated energy in the subsynchronous oscillation process, the oscillation is represented as a positive damping characteristic, the transient energy converged into the power grid is gradually reduced, and the oscillation is finally converged;
when W isHSWhen being equal to 0, the direct-drive fan does not emit and does not absorb the dissipated energy, the oscillation is represented by the undamped characteristic, and the system is in constant-amplitude oscillation.
7. The system of claim 6, wherein the system stability detection results output by the result output module include oscillation divergence, oscillation convergence, and constant amplitude oscillation.
8. The system of claim 4, wherein an input port of the data acquisition module is connected with a data output port of a direct-drive permanent magnet wind power system, an output port of the data acquisition module is connected with an input port of the dissipated energy calculation module, an output port of the dissipated energy calculation module is connected with an input port of the stability detection module, and an output port of the stability detection module is connected with an input port of the result output module.
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