CN107276120B - Doubly-fed fan synchronous machine system and method for restraining oscillation of synchronous generator - Google Patents
Doubly-fed fan synchronous machine system and method for restraining oscillation of synchronous generator Download PDFInfo
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Abstract
The invention discloses a double-fed fan synchronous machine system and a method for inhibiting oscillation of a synchronous generator; the method comprises the steps that a dq axis component signal of the power grid voltage is obtained by detecting the power grid voltage through a phase-locked loop, and two compensation signals are obtained through processing of two different error amplifiers and phase compensator units; the two compensation signals are respectively used as feedforward of the current control of the converter at the rotor side of the wind driven generator and are added to the instruction value of the dq axis component of the rotor current to respectively compensate the dq component of the rotor current. The internal potential amplitude phase of the doubly-fed wind turbine is controlled through the compensation control of the rotor current, the amplitude phase of the internal potential of the synchronous motor is further influenced through the power transmission line, and the effect of restraining the oscillation of the synchronous generator is achieved. Due to the fact that the corresponding speed of the current loop is high, the electronic current dq component can track the instruction value quickly, therefore, when the synchronous generator oscillates, the oscillation signal can be extracted quickly, and positive damping is provided for oscillation of the rotor of the synchronous generator quickly through the additional stable signal.
Description
Technical Field
The invention belongs to the field of new energy power generation, and particularly relates to a double-fed fan synchronous machine system and a method for inhibiting oscillation of a synchronous generator.
Background
China has become the first energy producing and consuming countries in the world since 2010, however, the undesirable energy consuming structure causes China to face serious energy problems at the same time. On the one hand, the supply of coal and petroleum in China has the problem of safety risk. From the aspect of energy supply, the energy situation in China is more vulnerable with the rapid increase of the total demand and the increasing of the external dependence. On the other hand, the large consumption of coal and oil poses serious environmental problems. China has become the first major carbon-emitting country in the world since 2008. The main cause of the haze problem in China is also due to the use of a large amount of coal and petroleum. According to the Paris climate agreement signed in 2016, China proposes that the emission of carbon dioxide reaches a peak value in 2030 years and strives to be realized as early as possible. The total carbon dioxide emission in domestic production in 2030 years is reduced by 60-65% compared with 2005, and the non-fossil energy accounts for about 20% of the consumption proportion of primary energy. It can be seen that reducing the specific gravity of fossil energy consumption such as coal has become the development direction of the future countries. The use of renewable energy is an important measure to solve this problem. Among them, wind power generation is one of the most potential forms of renewable energy.
Although the wind power generation in China starts late, the development is rapid. According to statistics, the wind energy reserves which can be developed and utilized by China are about 10 hundred million kilowatts, wherein the wind energy reserves on the land are about 2.53 hundred million kilowatts (calculated according to the data of the height of 10 meters above the ground), and the wind energy reserves which can be developed and utilized on the sea are about 7.5 hundred million kilowatts. According to statistics of the national energy agency, the capacity of a grid-connected wind generating set in China reaches 14864 ten thousand kilowatts and accounts for 9.03 percent of the capacity of the grid-connected set by 2016 years, the generated energy is steadily improved in recent years, and the power ratio of wind power generation reaches 4 percent in 2016. Because the wind resources in China are unevenly distributed, a large amount of high-quality wind resources are concentrated in northwest areas and northeast areas. Particularly, in inner Mongolia, Xinjiang and Gansu, the wind power generation installation accounts for 23.15%, 22.91% and 26.9% of the total installation of the whole province respectively; in the whole power grid of the northwest five provinces, the accumulated grid-connected wind power accounts for 19.6% of the total installed amount of the whole power grid. It can be seen that the proportion of wind power in northwest and northeast regions of China is already quite high. Wind power has become the primary power source in local power grids. With the increasing proportion of wind power generation in power systems, the influence of the wind power generation on the dynamic process and stability of the power systems gradually appears, and the wind power generation becomes a focus of attention in the industry. In particular, in recent years, a plurality of wind power off-grid accidents occur, and the safe and stable operation of a power system is seriously threatened. Research on characteristics of wind power generation and influence of wind power generation on safety and stability of a power system is urgent
Since in conventional power systems the synchronous generator is the primary, or even the only, power source, the dynamics directly determine the dynamics of the system. The situation is different as the wind power permeability is improved. The wind power generator needs to have a deeper understanding of the effect of low frequency oscillations of the synchronous generator. On the one hand, some research results find that the damping of the system gradually becomes stronger as the permeability and the output of the doubly-fed wind generator increase, which is considered to be caused by the fact that the doubly-fed wind generator is used as an asynchronous generator, and slip power is generated to provide positive damping to the system. On the other hand, some studies find that by replacing the synchronous generator, the system damping is reduced as the wind permeability is increased, which is considered to be caused by the increased tidal current, because the sensitivity analysis finds that the damping has low sensitivity to the wind generator, and the rapid voltage control does not substantially change the system damping. In other studies, it was thought that wind generators might both enhance and attenuate damping. Different studies have yielded contradictory results due to the conditions of the comparison. If a wind driven generator is added in the system, the change of topology and tide can be caused, and the change of the damping of the synchronous generator can be caused by the change of the topology and the tide; however, if the synchronous generator with equal capacity is replaced, the damping of the synchronous generator is affected by the synchronous generator, and it is difficult to explain what effect is caused to the system damping change after the wind driven generator is connected. Thus, logically, it is necessary to find a reference scenario that has no damping effect on the system.
In summary, the wind power generator has abundant characteristics, and the damping effect on the synchronous generator is possible. Further research is needed on the mechanism and physical process of the wind power generator to influence the synchronous generator.
Disclosure of Invention
Aiming at the defects or improvement requirements of the prior art, the invention provides a method for inhibiting the oscillation of the synchronous generator based on the doubly-fed wind turbine generator, breaks through the limitation that the damping influence of the wind turbine generator on the synchronous generator is undefined, and realizes the function of controlling the wind turbine generator to provide positive damping for the synchronous generator, thereby inhibiting the oscillation of the synchronous generator.
The invention provides a synchronous machine system of a double-fed fan, which comprises: synchronous generator SG, wind power generator, rotor-side converter, grid-side inductor LgThe direct current capacitor C, the phase-locked loop and the signal processor; the input end of the phase-locked loop is used for being connected to a power grid, the phase-locked loop is used for collecting a power grid voltage signal and outputting a power grid voltage amplitude variable quantity d-axis component after the power grid voltage signal is converted
And phase variation q-axis componentThe input end of the signal processor is connected to the output end of the phase-locked loop, and the signal processor is used for obtaining the d-axis component of the amplitude variation of the power grid according to the d-axis component
And phase variation q-axis componentOutputting a rotor side current loop auxiliary control signal irdconAnd irqcon(ii) a The control end of the rotor-side converter is connected to the output end of the signal processor, and the output end of the rotor-side converter is connected to the current control end of the wind driven generator; the capacitor C is connected between the connection ends of the grid-side converter and the rotor-side converter, and the other end of the capacitor C is grounded; when the network voltage fluctuates due to the oscillation of the synchronous machine, the current control command i is changed according to the auxiliary control signal of the current loop controller of the rotor-side converterrFromAnd the amplitude and the phase of the potential in the rotor voltage output by the rotor side converter are changed, so that the air gap magnetic field of the synchronous generator is changed, the output voltage of the stator is changed, and the amplitude and the phase of the potential in the synchronous generator are further influenced by the power transmission line.
Still further, the phase locked loop includes: a Park converter, a PI controller and an integrator; the voltage input end of the Park converter is used for receiving a power grid voltage signal VA、VB、VCThe feedback input end of the Park converter is connected to the output end of the integrator, and the Park converter is used for outputting a d-axis component of the grid amplitude variation quantity through a first output end after the two-phase rotating coordinate system conversion is carried out on the grid voltage signal
And outputting q-axis component of phase variation of power grid from second output terminal
The output of the Park converter is the output of the phase-locked loop. The input end of the PI controller is connected to the second output end of the Park converter, and the PI controller is used for controlling the q-axis componentAfter PI treatment omega is obtainedpIndicating the power grid frequency measured by the phase-locked loop; the input end of the integrator is connected to the output end of the PI controller; the integrator is used for the pair of omegapObtaining a power grid voltage theta after integration processingpAs the feedback input of the Park transformation.
Still further, the signal processor includes: for the first output of the phase-locked loop
In other words, the input end of the first error amplifier and the first phase compensator which are connected in sequence is used for receiving the d-axis component
For the second output of the phase-locked loopA high-pass filter, a second error amplifier and a second phase compensator which are connected in sequence; the input end of the high-pass filter is used for receiving the q-axis component
The output end of the first phase compensator is used for outputting an auxiliary control signal i of a rotor side current looprdcon(ii) a The output end of the second phase compensator is used for outputting a current loop auxiliary control signal i of the grid-side converterrqcon。
Further, the rotor-side converter includes: the adder, the PI regulator, the vector modulator SVM and the switch circuit are connected in sequence; the first input end of the adder is used for receiving a rotor side current reference command value idref/iqrefA second input terminal for receiving a current auxiliary control signal irdcon/irqconAnd a third input terminal for receiving a q-axis component i of the rotor currentrd/irqThe output end of the switch circuit outputs a current control command i for controlling the generatorr(ii) a When the power grid normally operates, the current auxiliary control signal irdcon/irqconIs zero, idref/iqrefAnd ird/irqObtaining a current error value after addition, and obtaining a rotor voltage control signal for controlling a switching sequence of the first switching circuit after the current error value is subjected to PI regulation and vector modulation in sequence; when the grid voltage fluctuates due to oscillations of the synchronous generator, irdcon/irqconWhen the voltage amplitude and the phase fluctuation component of the detected power grid act on the current loop control branch circuit through the adder, the current control instruction i is changedrd/irqSo as to change the amplitude and phase of the rotor voltage output by the rotor-side converter, thereby changing the air-gap magnetic field of the synchronous generator, further changing the output voltage of the stator, and influencing the synchronous generator by the synchronous transmission lineThe magnitude and phase of the electrical potential within the machine, and thus the oscillations, provide positive damping, damping the oscillations of the synchronous generator.
The invention also provides a method for inhibiting the oscillation of the synchronous generator based on the double-fed wind turbine generator, which comprises the following steps:
(1) processing the collected power grid voltage signal to obtain a d-axis component representing the power grid voltage amplitude
And a q-axis component representing the phase of the grid voltage
(2) D-axis component of grid voltage amplitude
Carrying out error amplification and phase compensation to obtain a first auxiliary control signal i of a current loop controller of the rotor-side converterrdcon(ii) a Q-axis component of grid voltage amplitude
Carrying out error amplification and phase compensation to obtain a second auxiliary control signal i of the current loop controller of the rotor-side converterrqcon；
(3) When the network voltage fluctuates due to oscillation of the synchronous generator, the current control command i is changed according to the auxiliary control signal of the current loop controller of the rotor-side converterrTherefore, the instruction value of the rotor voltage output by the rotor side converter is changed, the air gap magnetic field of the synchronous generator is changed, the output voltage of the stator is changed, the synchronous transmission line influences the amplitude and the phase of the electric potential in the synchronous generator, positive damping is provided by oscillation, and the oscillation of the synchronous generator is restrained.
Furthermore, in step (1), the two-phase rotating coordinate system transformation is performed on the grid voltage signal to obtain the d-axis component of the grid voltage amplitude
And q-axis component
Compared with the prior art, the technical scheme provided by the invention has the advantages that under the condition of large-scale wind power generation grid connection, when the synchronous machine oscillates in the power grid, the voltage amplitude and the phase of the power grid are directly processed and fed back through the double-fed wind power generator phase-locked loop signal, namely the positive damping torque is provided for the synchronous machine, so that the oscillation of the synchronous machine is inhibited, the equipment is faster than the traditional oscillation inhibiting equipment, the bandwidth of the power grid oscillation signal measured by the phase-locked loop is larger, the oscillation modes of the synchronous machine such as low-frequency oscillation, subsynchronous oscillation and the like can be inhibited simultaneously, and the investment cost of the power grid can be saved in the economic aspect compared with the condition that other equipment such as a PSS (power system stabilizer) and the like is additionally arranged.
Drawings
FIG. 1 is a schematic diagram of a double-fed wind turbine generator system for suppressing oscillation of a synchronous generator according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a phase-locked loop control architecture provided by an embodiment of the present invention;
FIG. 3 is a schematic diagram of a signal processing structure of an auxiliary control signal of a current loop controller of a rotor-side converter according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a structure of a rotor-side converter current loop controller for assisting a control signal to control the output voltage of the rotor-side converter.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
According to the invention, the influence of the phase-locked loop is deeply researched, the interaction between the internal potential power angle of the doubly-fed wind generator and the power angle of the synchronous generator is analytically researched, and the phenomenon that the doubly-fed wind generator can remarkably participate in oscillation to cause continuous oscillation when the phase-locked loop is in weak damping and the bandwidth is close to the oscillation frequency of the synchronous generator is found. Based on the research, the additional control signal is added to the rotor-side converter of the doubly-fed wind turbine, so that the amplitude phase of the internal potential of the generator is controlled to influence the amplitude phase of the internal potential of the synchronous generator, and the oscillation of the synchronous generator is restrained.
The invention provides a method for inhibiting oscillation of a synchronous generator based on a doubly-fed wind turbine generator, which is characterized in that two disturbance quantities capable of representing system oscillation are obtained by acquiring signals of grid-connected side voltage through a phase-locked loop and performing Park transformation and subsequent error amplification and phase compensation processing, and an auxiliary control signal is provided for controlling a current control loop of a rotor side converter, so that the amplitude and the phase of an internal potential output by the rotor side converter of a doubly-fed motor are controlled, the amplitude phase of the internal potential of the synchronous motor is further influenced through a power transmission line, and the positive damping effect of a fan generator on the synchronous generator is further realized. According to the oscillation theory, the larger the positive damping of the system is, the faster the system oscillation is attenuated, the oscillation divergence may be caused by the insufficient damping of the system, and the positive damping is provided for the system, so that the oscillation degree of the system can be effectively inhibited. The invention can provide positive damping for the synchronous machine by controlling the fan generator without changing the original control frame, thereby inhibiting the oscillation of the synchronous generator. In consideration of technology and economy, the invention adopts the technical scheme that through the existing control of the doubly-fed wind driven generator, a signal detected and processed by a phase-locked loop is an auxiliary control signal controlled by a current loop of a rotor-side converter, and positive damping is provided for the synchronous generator, so that the oscillation of the synchronous generator is suppressed.
The core content of the invention is that terminal voltage signals detected by a phase-locked loop are processed to form two auxiliary control signals, and the rotor voltage is controlled by auxiliary control of a current loop of a rotor-side converter of the doubly-fed wind turbine so as to control the amplitude and the phase of an internal potential output by the rotor converter. The d and q axis components of the signal obtained by the phase-locked loop
The disturbance components respectively represent the amplitude of the voltage of the power grid and the disturbance components of the angular speed, and the auxiliary control signals of the current loop controller of the rotor side converter are obtained after the disturbance components pass through the first error amplifier, the second error amplifier, the first phase compensator and the second phase compensator, so that the amplitude and the phase of the internal potential output by the rotor side are controlled. Therefore, when the synchronous machine generates subsynchronous oscillation, the phase-locked loop forms amplitude and angular velocity disturbance components by detecting a power grid voltage fluctuation signal, feeds the amplitude and the phase of the voltage output by the rotor-side converter back to the rotor-side current loop controller, controls the amplitude and the phase of the voltage output by the rotor-side converter, and further influences the amplitude phase of the internal potential of the synchronous machine through the power transmission line, so that the oscillation of the synchronous generator is suppressed.
The basic principle is as follows: when the synchronous machine oscillates, the amplitude and the phase of the system voltage after passing through the power transmission line are correspondingly disturbed, and a voltage signal V at the grid-connected side is acquired by utilizing the phase-locked loopA、VB、VCCarrying out Park conversion on the Q-axis component under a phase-locked loop coordinate system to obtain a q-axis component
And d-axis component
Using q-component of grid-connected side voltage
And integrating to obtain the angular speed change value of the voltage phase of the power grid. And obtaining a d-axis current instruction additional compensation signal controlled by a current loop of the rotor-side converter after passing through the first error amplifier and the first phase compensator. Using d-axis component of grid-connected side voltage
An additional compensation signal for the q-axis current command for the current loop control of the rotor-side converter is available as an amplitude disturbance component of the grid voltage. Adding the current control signal to the rotor converter to obtain a rotor d-axis current error signal and a rotor q-axis current error signal, and obtaining a rotor d-axis voltage signal and a rotor q-axis voltage signal through a PI controller linkVoltage signals forming a rotor voltage vector. And the amplitude and the phase of the internal potential output by the double-fed motor rotor side converter are further controlled, and the amplitude phase of the internal potential of the synchronous motor is adversely affected by the transmission line, so that the effect of controlling the wind driven generator to provide positive damping for the synchronous generator is realized, and the oscillation of the synchronous generator can be inhibited.
For further explanation of the method and system for suppressing oscillation of a synchronous generator based on a doubly-fed wind turbine provided by the embodiments of the present invention, the following is detailed with reference to the accompanying drawings:
as shown in fig. 1, a method for suppressing oscillation of a synchronous generator based on a doubly-fed wind turbine includes: synchronous generator and side inductor X of synchronous generatortWind driven generator, rotor side converter, grid side converter and grid side inductor LgA capacitor C, a phase-locked loop and a signal processor. When the synchronous generator oscillates, the generator passes through XtSo that the grid-connected point voltage also changes. The wind power generator converts wind power resources into electric power to be transmitted to a power grid, the rotor side converter controls the rotor excitation voltage of the generator, further controlling the stator voltage, the phase-locked loop controls the doubly-fed wind driven generator to track the phase of the power grid and output the required power by collecting the amplitude and the phase change of the power grid voltage and providing the amplitude and the phase change to a controller of the rotor-side converter, the signal processor is the core of the method of the invention, and the signal acquired by the phase-locked loop is processed, thereby realizing the extraction of the voltage change component of the power grid, further provides an auxiliary control signal of a current loop dq axis controller of the rotor side converter, thereby controlling the output voltage of the doubly-fed wind power generator through the auxiliary control signal of the rotor side converter, the amplitude and the phase of the electric potential in the synchronous generator are further influenced by the power transmission line, positive damping is provided for the oscillation of the synchronous generator, and the oscillation of the synchronous generator is restrained.
As shown in fig. 2, the phase locked loop includes: a Park converter 11, a PI controller 12, and an integrator 13. Stator voltage orientation is achieved. The input of the three-phase voltage tracking device is three-phase voltage, and the output of the three-phase voltage tracking device is d-axis and q-axis voltage components of the tracked voltage vector amplitude and phase change of the stator terminal. The transformation between the stationary three-phase coordinate system and the rotating dq coordinate system is as followsFormula (1). Wherein theta ispThe phase of the dq coordinate system is rotated for the phase locked loop.
Suppose that the three phase voltages are respectively
Then the components in the rotating dq coordinate system can be obtained by equation (1) as
When theta ispWhen ω t + γ, it is apparent that there is Vsq0. Then theta is at this timepIs equal to the phase of the terminal voltage vector, and is corresponding
The voltage amplitude is represented. The resulting phase locked loop is then constructed using this principle. As shown in (2) above, the first step,the signal takes tracking the amplitude of the power grid as a target;
the signal is aimed at tracking the phase of the power grid, the phase of the voltage can be obtained through the PI controller and the integrator, and the phase is fed back to the Park converter 11, so that the tracking of the phase of the power grid is realized.
Two signals which need to be extracted for the signal processor respectively represent the amplitude and the phase disturbance of the system voltage, and the fluctuation component corresponding to the grid voltage is obtained by the signal processor and is used for current loop auxiliary control of the rotor-side converter.
The invention aims to solve the problem of synchronous machine oscillation possibly caused by the weakening of system damping under the condition of large-scale wind power generation grid connection in the existing double-fed wind power generator control technology. The method for inhibiting the oscillation of the synchronous generator based on the doubly-fed wind turbine finally aims to detect the frequency signal of the oscillation generated by the system through the phase-locked loop to serve as an auxiliary control signal for controlling the current of the rotor side of the doubly-fed wind turbine generator, so that the output voltage of the rotor side is controlled, the amplitude phase of the internal potential of the synchronous generator is further influenced through the power transmission line, the damping of the synchronous generator is increased, the oscillation of the synchronous generator is further inhibited, and a feasible solution is provided for stabilizing a large-scale wind power generation grid-connected power system.
The system structure is shown in fig. 1, and mainly comprises a double-fed wind driven generator phase-locked loop and a signal processor for detecting signals, and generates an auxiliary control signal of a rotor side current loop controller to control the output voltage of a rotor side converter. The phase-locked loop 1 is obtained by detecting the voltage of the power grid
Representing a fluctuation in the amplitude of the grid voltage,
representing the voltage phase fluctuation, the signal processor 2 obtains the auxiliary control signal i of the rotor-side and grid-side convertersrdcon/irqconThe output voltage of the rotor-side converter is controlled.
FIG. 2 shows a typical phase locked loop controller for a doubly fed wind generator, which detects a grid voltage signal VA、VB、VCThen, the Q-axis component is obtained by carrying out Park transformation on the Q-axis component under a phase-locked loop coordinate system
And d-axis component
The phase-locked loop structure comprises a park converter 11, a PI controller 12 and an integrator 13, wherein the park converter 11 is used for changing three-phase sine wave quantity of a power grid to a two-phase rotating coordinate systemInstead, the q-axis component of the voltage is passed through the PI controller 12 to obtain ωpAnd then the voltage theta of the power grid is obtained through the integrator 13p. Wherein the signal that the signal processor 2 needs to receive is the q-axis component
And d-axis component
Representing the fluctuations in voltage amplitude and phase, respectively.
Fig. 3 shows a specific structure of the signal processor 2, which includes a high-pass filter 23, first and second error amplifiers 21 and 24, and first and second phase compensators 22 and 25. Two disturbance signals obtained in the phase-locked loop 1
Obtaining the variation component of the grid voltage amplitude value after passing through the pass filter 23, in order to make the rotor side of the doubly-fed wind generator respond to the amplitude value of the grid voltage and the component of the angular velocity fluctuation, two error amplifiers and two phase compensators with different parameters are needed to be arranged, so that the amplitude value of the grid voltage and the angular velocity fluctuation component are respectively obtained after passing through the two error amplifiers and the two phase compensators, and then the current loop auxiliary control signal i of the rotor side converter is obtainedrdconAnd irqcon。
Fig. 4 shows a current loop controller 3 of a rotor-side converter, which includes an adder 31, a PI regulator 32, a vector modulator SVM33, and a switching circuit 36. Signal irdconAnd irqconCurrent auxiliary control signal, i, for output of signal processor 2rdrefAnd irqrefFor the current reference command value, irdAnd irqAre the d and q axis components of the rotor current. When the power grid normally operates, the voltage signal obtained by the detection of the phase-locked loop
Zero when passing through the high-pass filter 23, and
orientation, and therefore from the analysis of formula (2)
So irqconAnd irdconThe signal is zero, in which case the current loop controller behaves as a typical current loop controller, irdrefAnd irdThe current error value is obtained by the adder 31, and the rotor voltage d-axis component u is obtained by the PI regulator 32rd，irqrefAnd irqThe current error value is obtained by the adder 34, and the rotor voltage q-axis component u is obtained by the PI regulator 35rq，urdAnd urqObtaining a switching sequence of the rotor voltage control signal control switching circuit 36 through a vector modulator SVM 33; when the grid voltage has low-frequency oscillation, irqconAnd irdconThe voltage amplitude and the angular velocity fluctuation components of the power grid are detected, the voltage amplitude and the angular velocity fluctuation components act on the current loop control branch through the adders 31 and 34, the rotor voltage output by the rotor side converter is changed through changing the current control instruction, the output current of the rotor converter is controlled, the output voltage of the stator is changed, the amplitude and the phase of the potential in the synchronous machine are influenced through the power transmission line, and the oscillation of the synchronous generator is restrained.
A method for restraining oscillation of a synchronous generator based on a doubly-fed wind turbine generator set comprises the following steps:
firstly, a phase-locked loop collects a power grid voltage signal to obtain two d-axis components representing power grid voltage disturbance of synchronous machine oscillation
Component of q axis
A second step of
Obtaining a voltage disturbance component by a high pass filter of a signal processorRespectively, then respectively
Obtaining an auxiliary control signal i of the rotor side current loop controller through two paths of error amplifiers and a phase compensator of the signal processorrqconAnd irdcon；
And thirdly, an auxiliary control signal obtained by the signal processor and a current loop dq shaft control loop of the rotor side converter form a closed loop together to control the rotor side output voltage of the doubly-fed wind driven generator, the internal potential amplitude and the phase of the synchronous generator are further influenced through a power transmission line, positive damping is provided for the system, and oscillation of the synchronous generator is further inhibited.
The method has the advantages that under the condition of grid connection of a large-scale wind driven generator, the limitation that the double-fed wind driven generator has undefined damping influence on the synchronous generator is overcome, the method has a better suppression effect on the oscillation of the synchronous generator, is simple and understandable from the principle, and only needs to add an auxiliary control module to generate a corresponding auxiliary control signal under the condition of not changing the existing control strategy of the double-fed wind driven generator from the realization and economic aspects, so that the fan is suppressed from the oscillation of the synchronous generator.
The method for inhibiting the oscillation of the synchronous generator based on the double-fed fan has good economical efficiency and easy operability. It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (6)
1. A synchronous quick-witted system of doubly-fed fan, its characterized in that includes: synchronous generator SG, wind driven generator, rotor side converter, grid side converter and grid side inductor LgCapacitor C, lockA phase loop and a signal processor;
the input end of the phase-locked loop is used for being connected to a power grid, the phase-locked loop is used for collecting a power grid voltage signal and outputting a d-axis component of a power grid voltage amplitude variation after the power grid voltage signal is converted
And q-axis component representing phase variation of power grid
The input end of the signal processor is connected to the output end of the phase-locked loop, and the signal processor is used for processing the d-axis component according to the grid voltage amplitude variation
Output d-axis auxiliary control signal irdconA control loop to the rotor side current loop d-axis; the signal processor represents q-axis component of power grid phase variation according to the characteristicOutput q-axis auxiliary control signal irqconA control loop to the rotor side current loop q axis;
the network side inductor LgIs used for being connected to a power grid, the grid side inductance LgThe other end of the first and second switches is connected to the input end of the grid-side converter;
the control end of the grid-side converter is connected to the output end of the signal processor;
the input end of the rotor-side converter is connected to the output end of the grid-side converter, the control end of the rotor-side converter is connected to the output end of the signal processor, and the output end of the rotor-side converter is connected to the current control end of the wind driven generator; one end of the capacitor C is connected to the connecting end of the grid-side converter and the rotor-side converter, and the other end of the capacitor C is grounded;
when the power grid is poweredWhen the voltage fluctuates due to the oscillation of the synchronous machine, the auxiliary control signal i is based on the d-axis of the current loop controller on the rotor siderdconAnd q-axis auxiliary control signal irqconChanging the current control command irTherefore, the amplitude and the phase of the potential in the rotor voltage output by the rotor-side converter are changed, the air gap magnetic field of the synchronous generator is changed, the output voltage of the stator is changed, and the amplitude and the phase of the potential in the synchronous generator are further influenced through the power transmission line.
2. The doubly fed wind turbine synchronous machine system of claim 1, wherein the phase locked loop comprises: a Park converter (11), a PI controller (12) and an integrator (13);
the voltage input end of the Park converter (11) is used for receiving a power grid voltage signal VA、VB、VCThe feedback input end of a Park converter (11) is connected to the output end of the integrator (13), and the Park converter (11) is used for outputting a q-axis component representing the phase variation of the power grid from a second output end after the two-phase rotating coordinate system conversion is carried out on the power grid voltage signal
And outputting the d-axis component of the amplitude variation of the grid voltage from the first output terminal
The output of the Park converter (11) is the output of the phase-locked loop (1);
the input end of the PI controller (12) is connected to the second output end of the Park converter (11), and the PI controller (12) is used for comparing the q-axis component representing the phase variation of the power grid
After PI treatment omega is obtainedp；
The input end of the integrator (13) is connected to the output end of the PI controller (12); the integrator (13) is used for the pair of omegapObtaining the voltage of the power grid after integral processingPhase thetapAs a feedback input for the Park transformation.
3. The doubly fed wind turbine synchronous machine system of claim 1, characterized in that said signal processor (2) comprises: a first error amplifier (21) and a first phase compensator (22) which are connected in sequence, and a high-pass filter (23), a second error amplifier (24) and a second phase compensator (25) which are connected in sequence;
the input end of the first error amplifier (21) is used for being connected to the first output end of the phase-locked loop (1), and the output end of the first phase compensator (22) is used for outputting a d-axis auxiliary control signal i of a rotor side current loop controllerrdcon；
The input end of the high-pass filter (23) is connected to the second output end of the phase-locked loop (1), and the output end of the second phase compensator (25) is used for outputting a q-axis auxiliary control signal i of a rotor side current loop controllerrqcon。
4. A synchronous machine system for doubly fed wind turbines as claimed in any of claims 1 to 3, characterized in that said rotor-side converter (3) comprises: a first adder (31), a second adder (34), a first PI regulator (32), a second PI regulator (35), a vector modulator SVM (33), and a switching circuit (36);
the first input end of the first adder (31) is used for receiving a reference command value i of the rotor side d-axis currentdrefAnd the second input end is used for receiving a d-axis auxiliary control signal i of the rotor side current loop controllerrdconAnd a third input terminal for receiving a d-axis component i of the rotor currentrdA first input of the second adder (34) is used for receiving a rotor side q-axis current reference command value iqrefA second input terminal for receiving q-axis auxiliary control signal i of the rotor-side current loop controllerrqconAnd a third input terminal for receiving a q-axis component i of the rotor currentrqThe output end of the switch circuit (36) outputs a current control command i for controlling the generatorr；
D-axis auxiliary control of rotor side current loop controller when power grid normally operatesSignal irdconAnd q-axis auxiliary control signal i of rotor side current loop controllerrqconAre all zero, idref/iqrefAnd ird/irqObtaining a current error value after subtraction, and obtaining a rotor voltage control signal for controlling a switching sequence of the switching circuit after the current error value is subjected to PI regulation and vector modulation in sequence;
when the grid voltage fluctuates due to oscillations of the synchronous generator, irdcon/irqconWhen the voltage amplitude and the phase fluctuation component of the detected power grid act on the current loop control branch circuit through the adder, the current control instruction i is changedrTherefore, the amplitude and the phase of the rotor voltage output by the rotor-side converter are changed, the air gap magnetic field of the synchronous generator is changed, the output voltage of the stator is changed, the synchronous transmission line influences the amplitude and the phase of the electric potential in the synchronous generator, and therefore positive damping is provided by oscillation, and the oscillation of the synchronous generator is restrained.
5. A method for suppressing oscillation of a synchronous generator based on the doubly-fed wind turbine synchronous machine system of claim 1, characterized by comprising the following steps:
(1) processing the collected grid voltage signal to obtain a d-axis component representing the amplitude variation of the grid voltage
And q-axis component representing phase variation of power grid
(2) D-axis component of grid voltage amplitude variation
Carrying out error amplification and phase compensation to obtain a d-axis auxiliary control signal i of the rotor side current loop controllerrdcon(ii) a Q-axis component representing phase variation of power grid
Carrying out error amplification and phase compensation to obtain a q-axis auxiliary control signal i of the rotor side current loop controllerrqcon；
(3) When the grid voltage fluctuates due to the oscillation of the synchronous generator, the auxiliary control signal i is generated according to the d-axis of the rotor side current loop controllerrdconAnd q-axis auxiliary control signal irqconChanging the current control command irTherefore, the instruction value of the rotor voltage output by the rotor-side converter is changed, the air gap magnetic field of the synchronous generator is changed, the output voltage of the stator is changed, the synchronous transmission line influences the amplitude and the phase of the potential in the synchronous generator, positive damping is provided by oscillation, and the oscillation of the synchronous generator is restrained.
6. The method of claim 5, wherein in step (1), the phase-locked rotating coordinate transformation is performed on the grid voltage signal to obtain the d-axis component of the grid voltage amplitude variation
And q-axis component representing phase variation of power grid
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| CN109274130B (en) * | 2018-11-19 | 2022-03-22 | 贵州大学 | No-load grid-connected phase correction control method for doubly-fed wind generator |
| CN109755964B (en) * | 2019-03-18 | 2022-06-07 | 哈尔滨工业大学 | Control method for improving stability of double-fed wind turbine generator under weak grid condition |
| DE102019117477A1 (en) * | 2019-06-28 | 2020-12-31 | Wobben Properties Gmbh | Method for minimizing generator vibrations |
| CN110323746B (en) * | 2019-07-30 | 2020-10-16 | 华北电力大学 | Method and system for detecting stability of dissipated energy of direct-drive permanent magnet wind power system |
| CN110854912B (en) * | 2019-11-27 | 2023-05-26 | 中国石油大学(华东) | Current instruction control method for doubly-fed fan during fault ride-through in weak network environment |
| CN111082436B (en) * | 2019-12-27 | 2023-04-07 | 华北电力大学 | Direct-drive wind power plant oscillation suppression method and system based on phase-locked consistency |
| CN113328446B (en) * | 2020-02-28 | 2022-12-27 | 贵州电网有限责任公司 | Method and system for improving operation stability of new energy synchronous motor pair |
| CN112928781B (en) * | 2021-03-23 | 2022-06-14 | 南方电网科学研究院有限责任公司 | Double-fed fan transient stability control method and system, computer equipment and medium |
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