CN111030177B - Wind power generation grid-connected inverter and control method thereof - Google Patents
Wind power generation grid-connected inverter and control method thereof Download PDFInfo
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- CN111030177B CN111030177B CN201911345576.0A CN201911345576A CN111030177B CN 111030177 B CN111030177 B CN 111030177B CN 201911345576 A CN201911345576 A CN 201911345576A CN 111030177 B CN111030177 B CN 111030177B
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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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/76—Power conversion electric or electronic aspects
Abstract
The application provides a wind power generation grid-connected inverter and a control method thereof, and relates to the technical field of wind power generation. The control method of the wind power generation grid-connected inverter comprises the following steps: when a braking instruction is detected, controlling the inverter circuit to stop inverting; controlling a grid-connected switch to be disconnected; controlling an unloading circuit to unload; and finally, controlling the electronic brake switch to be closed. The wind power generation grid-connected inverter is simple in structure and reliable in operation, the control method can effectively control the direct-current bus voltage in the normal operation process of the wind power generator, and the braking of the wind power generator can be quickly, effectively and safely achieved when the wind power generator meets the braking condition.
Description
Technical Field
The application relates to the technical field of wind power generation, in particular to a wind power generation grid-connected inverter and a control method thereof.
Background
At present, a wind power generation grid-connected inverter generally comprises a rectification circuit, an unloading circuit, a boosting circuit and an inverter circuit. The wind power generation grid-connected inverter, the wind power generator and the power grid form a wind power generation grid-connected system. The three-phase alternating current output end of the wind driven generator is connected with the input end of the rectifying circuit, the output end of the rectifying circuit is connected with the input end of the booster circuit through the unloading circuit, the output end of the booster circuit is connected with the direct current side of the inverter circuit, and the alternating current side of the inverter circuit is connected with the power grid.
In order to ensure that the voltage of the dc bus is lower than a preset threshold value to prevent the inverter from being burnt due to an excessively high voltage, an unloading circuit is usually used for unloading in the prior art to suppress the rise of the voltage of the dc bus and ensure that the voltage of the dc bus is lower than the preset threshold value. However, when the wind speed rapidly increases, the dc bus voltage also rapidly increases, and the unloading by the unloading circuit is insufficient to suppress the increase in the dc bus voltage, resulting in an excessively high dc bus voltage. In the grid-connected operation process, when the wind driven generator needs to be braked, if the wind driven generator is directly unloaded to brake, the energy of the power grid flows back to the inverter, and the energy of the power grid is consumed; the existing braking method can not ensure the safe and effective braking of the wind driven generator and is easy to burn out the wind driven generator.
Disclosure of Invention
The wind power generation grid-connected inverter and the control method thereof are simple in structure and reliable in operation, and can prevent the energy of a power grid from flowing back to the inverter when a wind power generator brakes, so that the braking of the wind power generator is realized quickly, effectively and safely.
The specific technical scheme is as follows:
in a first aspect, a method for controlling a wind power grid-connected inverter is provided, where the method is applied to a control component of the wind power grid-connected inverter, and the wind power grid-connected inverter further includes: the control device comprises an electronic brake switch, a three-phase bridge type half-control rectifying circuit, an unloading circuit, an inverter circuit and a grid-connected switch, wherein the electronic brake switch is connected between the output end of a wind driven generator and the input end of the three-phase bridge type half-control rectifying circuit, the output end of the three-phase bridge type half-control rectifying circuit is connected with the input end of the unloading circuit, the output end of the unloading circuit is connected with a direct current bus, the direct current bus is connected with the direct current side of the inverter circuit, the alternating current side of the inverter circuit is connected with a power grid through the grid-connected switch, a control component is respectively connected with the electronic brake switch, the three-phase bridge type half-control rectifying circuit, the unloading circuit, the inverter circuit and the grid-connected switch, and the control of the wind power generation grid-connected inverter comprises the following steps: step S1, when a brake instruction is detected, controlling the inverter circuit to stop inverting; step S2, controlling the grid-connected switch to be disconnected; step S3, controlling the unloading circuit to unload; and step S4, controlling the electronic brake switch to be closed.
Optionally, before the step S2, the method further includes: judging whether the time length of the inversion circuit after the inversion is stopped reaches a first preset time length or not; if the first preset time period is reached, the step S2 is executed.
Optionally, the step S3 includes: and controlling the duty ratio of a power switch device in the unloading circuit to increase to 100% from zero according to a preset first step length.
Optionally, after step S3, the method further includes: and controlling the conduction of a power switch device in the three-phase bridge type semi-controlled rectifying circuit, and simultaneously carrying out current-limiting control on the output current of the wind driven generator.
Optionally, the controlling the conduction of the power switch device in the three-phase bridge type half-controlled rectification circuit includes: and controlling the duty ratio of a power switching device in the three-phase bridge type semi-controlled rectifying circuit to increase to 100% from zero according to a preset second step length.
Optionally, the current-limiting control of the output current of the wind turbine includes the following steps: and when the output current of the wind driven generator is judged to exceed the preset limit current value, reducing the duty ratio of a power switch device in the three-phase bridge type semi-controlled rectifying circuit according to a preset third step length so as to limit the output current of the wind driven generator to be continuously increased.
Optionally, the control method of the wind power generation grid-connected inverter further includes: in the process of carrying out current-limiting control on the output current of the wind driven generator, when the output current of the wind driven generator continuously exceeds a preset current-limiting value within a second preset time period, the electronic brake switch is controlled to be closed.
Optionally, the control method of the wind power generation grid-connected inverter further includes: sampling the rotating speed of the wind driven generator, and controlling the three-phase bridge type semi-controlled rectifying circuit to carry out maximum power tracking on the output of the wind driven generator according to a rotating speed-power curve table when the rotating speed of the wind driven generator is greater than a preset cut-in rotating speed of the wind driven generator and is less than a preset maximum rotating speed threshold value.
Optionally, the control method of the wind power generation grid-connected inverter further includes: in the process of controlling the three-phase bridge type half-controlled rectifying circuit to carry out maximum power tracking control on the output of the wind driven generator, when the voltage of the direct-current bus is detected to be higher than the preset grid-connected switch conducting voltage, the grid-connected switch is controlled to be conducted, and when the voltage of the direct-current bus is detected to be higher than the preset grid-connected voltage, the inverter circuit is controlled to carry out inversion output.
Optionally, the controlling the inverter circuit to perform inverting output includes the following steps: carrying out Clark Clarke transformation on the output current of the inverter circuit to obtain the alpha and beta two-phase static seat of the output current of the inverter circuitAlpha-axis current component i under the scalegαAnd a beta-axis current component igβ(ii) a For the alpha-axis current component igαAnd the beta-axis current component igβCarrying out Park conversion to obtain the alpha-axis current component igαAnd the beta-axis current component igβReactive current i under dq two-phase rotating coordinate systemgdAnd an active current igq(ii) a Carrying out proportional integral operation on the difference value of the direct current bus voltage and a preset reference voltage to obtain an active current instruction value i* gq(ii) a For the reactive current igdAnd a preset reactive current instruction value i* gdThe difference value is subjected to proportional integral operation to obtain a first voltage instruction value u* sd(ii) a For the active current igqAnd the active current command value i* gqThe difference value is subjected to proportional integral operation to obtain a second voltage instruction value u* sq(ii) a For the first voltage command value u* sdAnd the second voltage command value u* sqCarrying out Park inverse transformation to obtain a first controlled quantity u* sαAnd a second control quantity u* sβ(ii) a According to the first control quantity u* sαAnd the second control amount u* sβAnd performing Space Vector Pulse Width Modulation (SVPWM) to generate a driving signal for controlling the on-off of a power switch device in the inverter circuit.
Optionally, the control method of the wind power generation grid-connected inverter further includes: when the fact that the direct-current bus voltage is continuously smaller than the grid-connected voltage within a third preset duration and the grid-connected power of the wind power generation grid-connected inverter is smaller than a preset minimum grid-connected power is detected, or the fact that the power grid is abnormal is detected, the inverter circuit is controlled to stop inversion output, wherein the grid-connected power is the difference value of the output power of the wind power generator and the power consumed by the unloading circuit.
Optionally, the wind power generation grid-connected inverter further includes a manual brake switch, and the manual brake switch is disposed between the output end of the wind power generator and the electronic brake switch, and is used for manual braking when the electronic brake switch fails or is overhauled.
Optionally, the control method of the wind power generation grid-connected inverter further includes: when the voltage of the direct current bus is detected to be higher than a preset unloading voltage, the unloading circuit is controlled to unload so as to inhibit the voltage of the direct current bus from rising; the method specifically comprises the following steps: determining an initial duty cycle according to the following formula:
wherein D is1To initial duty cycle, U3For a predetermined unloading voltage, U4To a preset full off-load voltage, UdcFor the DC bus voltage, a preset complete unloading voltage U4Greater than a predetermined unloading voltage U3(ii) a Adjusting the duty cycle of a power switching device in the unloading circuit to the initial duty cycle; and controlling the duty ratio of a power switching device in the unloading circuit to be increased to 100% from the initial duty ratio according to a preset fourth step length.
Optionally, the control method of the wind power generation grid-connected inverter further includes: when the unloading duty ratio of the unloading circuit reaches a 100% complete unloading state, if the direct-current bus voltage still shows a rising trend and reaches a preset maximum voltage threshold value, controlling the duty ratio of a power switching device in the three-phase bridge type semi-controlled rectifying circuit to increase from zero according to a preset fifth step length, and simultaneously carrying out current limiting control on the output current of the wind driven generator; and detecting the voltage of the direct current bus in real time, executing braking action if the voltage of the direct current bus still rises to reach a preset braking condition, and disconnecting a power switch device in the three-phase bridge type semi-controlled rectifying circuit if the voltage of the direct current bus drops to or below a preset maximum voltage threshold.
On the other hand, this application still provides a wind power generation grid-connected inverter, wind power generation grid-connected inverter includes the control unit that is used for carrying out any one of above-mentioned methods, wind power generation grid-connected inverter still includes electronic brake switch, three-phase bridge type half-controlled rectifier circuit, off-load circuit, inverter circuit and grid-connected switch, electronic brake switch connect in aerogenerator output with between the three-phase bridge type half-controlled rectifier circuit input, three-phase bridge type half-controlled rectifier circuit's output is connected the input of off-load circuit, the output of off-load circuit connects direct current bus, direct current bus with inverter circuit's direct current side is connected, inverter circuit's alternating current side is connected with the electric wire netting through grid-connected switch, control unit respectively with electronic brake switch, three-phase bridge type half-controlled rectifier circuit, The unloading circuit, the inverter circuit and the grid-connected switch are connected.
Optionally, the three-phase bridge type half-controlled rectification circuit and the unloading circuit are integrated and packaged in the same IGBT module, and the inverter circuit is an IPM module.
In this application, when detecting the brake instruction, at first block inverter circuit power switch device's drive signal, stop the contravariant output, then the switch that is incorporated into the power networks of disconnection can prevent that the electric wire netting energy from to the unloading circuit backward flow, consuming the electric wire netting energy. The unloading circuit is controlled to unload until the unloading is completed (the unloading resistor is completely connected), then the power switch device of the lower bridge arm of the three-phase bridge type half-controlled rectifier bridge is controlled to be conducted, and meanwhile, the output current of the wind driven generator is controlled to be limited, so that the wind driven generator is prevented from being burnt out due to overlarge current; and finally, controlling the electronic brake switch to be closed, so that the wind driven generator is braked. The wind power generation grid-connected inverter is simple in structure and reliable in operation; in the braking process of the wind power generation grid-connected inverter, gradual unloading is realized through the cooperation of the unloading circuit and the three-phase bridge type half-controlled rectifier bridge, and finally the purpose of safe braking is achieved.
Of course, not all advantages described above need to be achieved at the same time in the practice of any one product or method of the present application.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a block diagram of a topology structure of a wind power generation grid-connected inverter system according to an embodiment of the present application;
fig. 2 is a schematic view of a topological structure of a wind power generation grid-connected inverter system according to an embodiment of the present application;
fig. 3 is a flowchart of a control method of a wind power generation grid-connected inverter according to an embodiment of the present application;
fig. 4 is a flowchart of an unloading control method for a wind power generation grid-connected inverter according to an embodiment of the present application;
fig. 5 is a flowchart of inversion control of a wind power generation grid-connected inverter according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The embodiment of the application provides a control method of a wind power generation grid-connected inverter, which is applied to a control component of the wind power generation grid-connected inverter, and referring to fig. 1, the wind power generation grid-connected inverter further comprises: the wind driven generator comprises an electronic brake switch, a three-phase bridge type half-control rectifying circuit, an unloading circuit, an inverter circuit and a grid-connected switch, wherein the input end of the three-phase bridge type half-control rectifying circuit is connected with the three-phase alternating current output end of a wind driven generator, the output end of the three-phase bridge type half-control rectifying circuit is connected with the input end of the unloading circuit, the output end of the unloading circuit is connected with a direct current bus, the direct current bus is connected with the direct current side of the inverter circuit, the alternating current side of the inverter circuit is connected with a power grid through the grid-connected switch, the electronic brake switch is arranged between the output end of the wind driven generator and the three-phase bridge type half-control rectifying circuit, and a control component is respectively connected with the three-phase bridge type half-control rectifying circuit, the unloading circuit, the inverter circuit, the electronic brake switch and the grid-connected switch. The wind driven generator can convert wind energy into electric energy and output three-phase alternating current; the three-phase bridge type semi-controlled rectifying circuit can rectify three-phase alternating current output by the wind driven generator and output direct current; the inverter circuit can invert the direct current output by the three-phase bridge type semi-controlled rectifying circuit and output alternating current to a power grid. The wind driven generator, the wind power generation grid-connected inverter and the power grid form a wind power generation grid-connected system.
Referring to fig. 2, the three-phase bridge type half-controlled rectifier circuit is composed of three diodes D1, D2, D3 and three controllable switching devices V2, V3, and V4, each of the three bridge arms includes a diode and a controllable switching device, and for design convenience, the lower bridge arm is a controllable switching device in this embodiment. The wind power generation grid-connected inverter may further include a machine side filter and a grid side filter. The machine side filter is arranged at the input end of the three-phase bridge type half-control rectification circuit and is used for filtering the alternating current output by the wind driven generator. The output end of the three-phase bridge type half-control rectification circuit is connected with an unloading circuit, the unloading circuit is composed of an unloading resistor R1 and a controllable power switch tube V1, the output end of the unloading circuit is connected with the input end of an inverter circuit after being connected with a bus capacitor C1 in parallel, the output end of the inverter circuit is connected with one end of a grid-side filter, the grid-side inverter is used for filtering three-phase alternating current output by the inverter circuit, the other end of the grid-side filter is connected with one end of a grid-connected switch, and the other end of the grid-connected switch is connected with a power grid.
The wind power generation grid-connected inverter can further comprise a double-circuit power supply auxiliary switch power supply, a first input end of the double-circuit power supply auxiliary switch power supply is connected with an input end of the inverter circuit, a second input end of the double-circuit power supply auxiliary switch power supply is connected with a power grid, and an output end of the double-circuit power supply auxiliary switch power supply is connected with the control component.
The double-circuit power supply auxiliary switch power supply can be powered by a power grid to the double-circuit power supply auxiliary switch power supply, and the double-circuit power supply auxiliary switch power supply can convert electric energy provided by the power grid into electric energy required by the control component to supply power to the control component. Or the double-circuit power supply auxiliary switch power supply can supply power to the double-circuit power supply auxiliary switch power supply from the direct current bus voltage connected to the input end of the inverter circuit, and the double-circuit power supply auxiliary switch power supply can convert the direct current bus voltage into electric energy required by the control part so as to supply power to the control part.
The specific working process of the double-circuit power supply auxiliary switching power supply is as follows:
under the condition that the power grid is not powered, when the fact that the direct-current bus voltage is lower than the working voltage of the double-circuit power supply auxiliary switch power supply is detected, the double-circuit power supply auxiliary switch power supply can not convert the direct-current bus voltage into electric energy required by the control component, namely the double-circuit power supply auxiliary switch power supply does not supply power to the control component. When the voltage of the direct current bus is detected to reach the working voltage of the double-circuit power supply auxiliary switch power supply, the double-circuit power supply auxiliary switch power supply can convert the voltage of the direct current bus into electric energy required by the control part, namely the double-circuit power supply auxiliary switch power supply supplies power to the control part. Under the condition that the power grid is electrified, the double-circuit power supply auxiliary switch power supply can supply power to the double-circuit power supply auxiliary switch power supply through the power grid, the double-circuit power supply auxiliary switch power supply can convert electric energy provided by the power grid into electric energy required by the control component to supply power to the control component, and therefore the reliability of communication and monitoring of the system and energy scheduling is improved.
The following will describe a control method of a wind power generation grid-connected inverter provided in an embodiment of the present application in detail with reference to specific embodiments, as shown in fig. 3, the specific steps are as follows:
and S1, when the brake command is detected, controlling the inverter circuit to stop inverting, namely stopping outputting the driving signal to the power switching device of the inverter circuit.
It should be noted that the brake instruction is a brake instruction triggered when the output current of the wind driven generator exceeds a preset brake current value, or a brake instruction triggered when the rotating speed of the wind driven generator exceeds a preset brake rotating speed, or a brake instruction triggered when the output voltage of the wind driven generator exceeds a preset over-voltage point, or a brake instruction triggered when a manual brake button is manually pressed.
And S2, controlling the grid-connected switch to be disconnected.
The grid-connected switch is controlled to be switched off, so that the energy of the power grid can be prevented from flowing backwards to the unloading circuit and consuming the energy of the power grid. Optionally, before the grid-connected switch is controlled to be switched off, the control component further determines whether the time length after the inversion of the inverter circuit is stopped reaches a first preset time length; and if the first preset duration is reached, executing the step of controlling the grid-connected switch to be disconnected. Here, waiting for the first preset duration makes the output current of the network side filter approach zero before controlling the grid-connected switch to be switched off, and then controlling the grid-connected switch to be switched off has no influence on the system, and the output voltage of the network side filter does not fluctuate, so that smooth switching from grid connection to grid disconnection can be realized.
And S3, controlling an unloading circuit to unload.
Optionally, the specific process of controlling the unloading circuit to unload may be: and controlling the duty ratio of a power switch device in the unloading circuit to increase from zero according to a preset first step until the duty ratio is increased to 100%, and the unloading resistor is always completely connected into the circuit.
And S4, controlling the electronic brake switch to be closed so as to lock the wind driven generator.
Further, in order to reduce the impact of the current on the wind turbine during the braking process, optionally, after step S3, the method further includes the step of controlling the power switching devices in the three-phase bridge type half-controlled rectification circuit to be turned on, and simultaneously performing current-limiting control on the output current of the wind turbine. The specific process of controlling the conduction of the power switch device in the three-phase bridge type semi-controlled rectifying circuit can be as follows: and controlling the duty ratio of a power switching device in the three-phase bridge type semi-controlled rectifying circuit to be increased to 100% from zero according to a preset second step length.
Because the output current of the wind driven generator can be gradually increased in the gradual conduction process of the power switch device in the three-phase bridge type semi-controlled rectification circuit, and when the power switch device is completely conducted, namely the three-phase output end of the wind driven generator is in short circuit, in the process, the output current of the wind driven generator must be monitored to prevent overcurrent from damaging the wind driven generator.
The current-limiting control of the output current of the wind driven generator provided by the embodiment of the application comprises the following steps: and when judging whether the output current of the wind driven generator exceeds a preset limiting current value, if so, reducing the duty ratio of a power switch device in the three-phase bridge type semi-controlled rectifying circuit according to a preset third step length so as to limit the output current of the wind driven generator to be continuously increased.
Optionally, in the process of performing current-limiting control on the output current of the wind driven generator, if the output current of the wind driven generator continuously exceeds the preset limiting current value within the second preset time period, the electronic brake switch is immediately controlled to be closed.
It should be noted that the braking process of the wind turbine generator is triggered under a braking condition, for example, the braking command may be that the output current of the wind turbine generator exceeds a preset braking current value, or the rotational speed of the wind turbine generator exceeds a preset braking rotational speed, or the output voltage of the wind turbine generator exceeds a preset overvoltage point, or a manual brake button is manually pressed.
Referring to fig. 4, the control method of the wind power generation grid-connected inverter of the present application further includes a separate unloading control, and the control component detects the dc bus voltage (the voltage U across the capacitor C1) in real time when the wind power generation grid-connected inverter is in operationdc). When the wind speed is high and the direct current bus voltage is detected to be higher than the preset unloading voltage (the unloading condition is established), the control component controls the unloading circuit to unload, so that the rise of the direct current bus voltage is restrained, and the direct current bus voltage is prevented from being overhigh.
In the embodiment of the application, the control component can unload by adjusting the duty ratio of the power switch device in the unloading circuit, and the specific process can be as follows:
s01, determining an initial duty ratio according to a preset duty ratio calculation formula, wherein the duty ratio calculation formula is as follows:
wherein D is1To initial duty cycle, U3For predetermined dischargeCharged voltage, U4To a preset full off-load voltage, UdcIs the dc bus voltage.
And S02, adjusting the duty ratio of the power switch device in the unloading circuit to the initial duty ratio.
And S03, controlling the duty ratio of the power switch device in the unloading circuit to increase to 100% from the initial duty ratio according to a preset fourth step.
S04, when the unloading resistance is completely connected, if the wind speed continues to increase, the DC bus voltage will also increase rapidly, the unloading circuit is used to unload the load to restrain the rise of the DC bus voltage, when the DC bus voltage continues to rise to the preset maximum voltage threshold, at this time, the control component controls the inverter circuit to stop the inversion output, and controls the duty ratio of the power switch device in the three-phase bridge type semi-control rectification circuit to increase from zero according to the preset fifth step length, so as to restrain the rise of the DC bus voltage.
In the process, the output current of the wind driven generator is subjected to current limiting control; and detecting the voltage of the direct current bus in real time, executing braking action if the voltage of the direct current bus still rises to reach a preset braking condition, and disconnecting a power switch device in the three-phase bridge type semi-controlled rectifying circuit if the voltage of the direct current bus drops to or below a preset maximum voltage threshold.
It is worth mentioning that in the braking process, the control part compares the unloading duty ratio when the brake is currently performed with the unloading duty ratio in the independent unloading process before the brake, and selects the larger duty ratio to perform unloading control, so that the quick brake is more facilitated.
Optionally, in the process of controlling the unloading circuit to perform unloading, the control component may further determine whether the unloading circuit is abnormal, and after determining that the unloading circuit is abnormal, the control component may output alarm information.
Optionally, the wind power generation grid-connected inverter further comprises a manual brake switch, and the manual brake switch is arranged between the output end of the wind power generator and the electronic brake switch and used for manual braking when the electronic brake switch fails or is overhauled.
According to the three-phase bridge type semi-controlled rectifying circuit, the direct-current bus voltage is restrained from rising by controlling the unloading of the unloading circuit and controlling the conduction of the power switch device in the three-phase bridge type semi-controlled rectifying circuit, the rising of the direct-current bus voltage can be effectively restrained, and the direct-current bus voltage is prevented from being too high. In the braking process, the unloading of the control unloading circuit is combined with the conduction of a switching device in the three-phase bridge type semi-controlled rectifying circuit to realize the rapid, effective and safe braking.
Optionally, the control unit may further perform maximum power tracking control on the output of the wind turbine, and the specific process may include the following steps:
sampling the rotating speed of the wind driven generator by using a detection device;
when the rotating speed of the wind driven generator is judged to be greater than the preset cut-in rotating speed of the wind driven generator and less than the preset maximum rotating speed threshold, the current rotating speed value of the wind driven generator is combined, and the output phase current reference value or the output power reference value of the wind driven generator is obtained by searching a rotating speed-power curve table of the wind driven generator;
and then carrying out deviation adjustment control on the output of the wind driven generator according to the output phase current reference value or the output power reference value of the wind driven generator.
The deviation adjustment Control is that the output phase current of the wind driven generator is differed from the reference value of the output phase current of the wind driven generator to obtain a current error value, and the current error value is subjected to deviation adjustment, such as Proportional-Integral Control (PI) or Proportional-Integral-derivative Control (PID), so as to obtain a PWM Control signal for controlling the three-phase bridge type half-Control rectification circuit of the wind driven generator; or the output power of the wind driven generator is differed with the power reference value of the wind driven generator to obtain a power error value, and the power error value is subjected to deviation adjustment to obtain a control signal for controlling the three-phase bridge type semi-controlled rectifying circuit.
It should be noted that there are various representations of the wind turbine power curve, for example, it can be expressed as the relation between the wind turbine rotation speed and the output power, the relation between the wind turbine output voltage and the output power, the relation between the wind turbine output current and the output voltage, or the relation between the wind turbine rotation speed and the output current, and the various power curves can be switched with each other.
Optionally, the control component may also perform grid-connected control, and the specific process may be: in the process of controlling the three-phase bridge type semi-controlled rectifying circuit to carry out maximum power tracking control on the output of the wind driven generator, when the voltage of a direct-current bus is detected to be higher than the preset grid-connected switch conduction voltage, the grid-connected switch is controlled to be conducted; and when the voltage of the direct-current bus is detected to be higher than the preset grid-connected voltage, controlling the inverter circuit to perform inversion output.
Referring to fig. 5, a specific process of controlling the inverter circuit to perform the inverter output may be:
clark Clarke transformation is carried out on the output current of the inverter circuit to obtain an alpha-axis current component i of the output current of the inverter circuit under an alpha-beta two-phase static coordinate systemgαAnd a beta-axis current component igβ(ii) a The Clarke transformation is performed on the output current of the inverter circuit, and the phase of the power grid voltage needs to be obtained, for example, the phase θ of the power grid voltage can be detected by a PLL (phase locked loop);
for the alpha-axis current component igαAnd a beta-axis current component igβCarrying out Park conversion to obtain an alpha axis current component igαAnd a beta-axis current component igβReactive current i under dq two-phase rotating coordinate systemgdAnd an active current igq；
Carrying out proportional integral PI operation on the difference value of the direct current bus voltage and a preset reference voltage to obtain an active current instruction value i* gq；
For reactive current igdAnd a preset reactive current instruction value i* gdPerforming PI operation on the difference value to obtain a first voltage instruction value u* sd；
For active current igqAnd an active current command value i* gqPerforming PI operation on the difference value to obtain a second voltage instruction value u* sq；
For the first voltage command value u* sdAnd a second voltage command value u* sqCarrying out Park inverse transformation to obtain a first controlled quantity u* sαAnd a second control quantity u* sβ；
According to a first control quantity u* sαAnd a second control quantity u* sβAnd performing Space Vector Pulse Width Modulation (SVPWM) to generate a driving signal for controlling the on-off of a power switch device in the inverter circuit.
Wherein, a preset reactive current instruction value i is adjusted* gdThe power factor of the wind power grid-connected inverter operation can be adjusted, for example, a preset reactive current instruction value i* gdWhen the power factor is 0, the unit power factor operation of the wind power generation grid-connected inverter can be realized.
Optionally, when detecting a grid-connected switch-out instruction, the control component may control the inverter circuit to stop inverting output, and the specific process may be: and when detecting that the direct-current bus voltage is smaller than the grid-connected voltage and the grid-connected power of the wind power generation grid-connected inverter is smaller than the preset minimum grid-connected power within a third preset time period, or detecting that the power grid is abnormal, controlling the inverter circuit to stop inverting output.
Based on the same technical concept, the application also provides a wind power generation grid-connected inverter, the wind power generation grid-connected inverter comprises a control component for executing any one of the methods, the wind power generation grid-connected inverter also comprises an electronic brake switch, a three-phase bridge type half-control rectifying circuit, an unloading circuit, an inverting circuit and a grid-connected switch, the input end of the three-phase bridge type half-control rectifying circuit is connected with the three-phase output end of the wind power generator, the output end of the three-phase bridge type half-control rectifying circuit is connected with the input end of the unloading circuit, the output end of the unloading circuit is connected with a direct current bus, the direct current bus is connected with the direct current side of the inverting circuit, the alternating current side of the inverting circuit is connected with a power grid through the grid-connected switch, the electronic brake switch is arranged between the three-phase bridge type half-control rectifying circuit and the output end of the wind power generator, and the control component is respectively connected with the electronic brake switch, the three-phase bridge type half-control rectifying circuit, the three-control half-control rectifying circuit, the electronic brake switch, the three-control bridge type half-control rectifying circuit, the electronic brake switch, the unloading circuit and the inverter circuit are connected with the grid-connected switch.
Optionally, the three-phase bridge type half-controlled rectification circuit and the unloading circuit are integrally packaged in the same IGBT (Insulated Gate Bipolar Transistor) Module, and the inverter circuit is an IPM Module (Intelligent Power Module).
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. Especially, as for the device and the system, since they are basically similar to the method embodiments, the description is simple, and the relevant points can be referred to the partial description of the method embodiments.
The above description is only for the preferred embodiment of the present application, and is not intended to limit the scope of the present application. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application are included in the protection scope of the present application.
Claims (14)
1. A method for controlling a wind power generation grid-connected inverter, the method being applied to a control component of the wind power generation grid-connected inverter, the wind power generation grid-connected inverter further comprising: the control device comprises an electronic brake switch, a three-phase bridge type half-control rectifying circuit, an unloading circuit, an inverter circuit and a grid-connected switch, wherein the electronic brake switch is connected between the output end of a wind driven generator and the input end of the three-phase bridge type half-control rectifying circuit, the output end of the three-phase bridge type half-control rectifying circuit is connected with the input end of the unloading circuit, the output end of the unloading circuit is connected with a direct current bus, the direct current bus is connected with the direct current side of the inverter circuit, the alternating current side of the inverter circuit is connected with a power grid through the grid-connected switch, a control component is respectively connected with the electronic brake switch, the three-phase bridge type half-control rectifying circuit, the unloading circuit, the inverter circuit and the grid-connected switch, and the control of the wind power generation grid-connected inverter comprises the following steps:
step S1, when a brake instruction is detected, controlling the inverter circuit to stop inverting;
step S2, controlling the grid-connected switch to be disconnected;
step S3, controlling the unloading circuit to unload;
step S4, controlling the electronic brake switch to be closed;
the brake instruction is triggered when the output current of the wind driven generator exceeds a preset brake current value, or when the rotating speed of the wind driven generator exceeds a preset brake rotating speed, or when the output voltage of the wind driven generator exceeds a preset overvoltage point, or when a manual brake button is manually pressed;
prior to the step S2, the method further includes:
judging whether the time length of the inversion circuit after the inversion is stopped reaches a first preset time length or not;
if the first preset time duration is reached, executing the step S2;
the method further comprises the following steps:
sampling the rotating speed of the wind driven generator, and controlling the three-phase bridge type semi-controlled rectifying circuit to carry out maximum power tracking on the output of the wind driven generator according to a rotating speed-power curve table when the rotating speed of the wind driven generator is greater than a preset cut-in rotating speed of the wind driven generator and is less than a preset maximum rotating speed threshold value;
when the rotating speed of the wind driven generator is greater than the preset cut-in rotating speed of the wind driven generator and less than the preset maximum rotating speed threshold value, the three-phase bridge type semi-controlled rectifying circuit is controlled to carry out maximum power tracking on the output of the wind driven generator according to a rotating speed-power curve table, and the method comprises the following steps:
when the rotating speed of the wind driven generator is judged to be greater than the preset cut-in rotating speed of the wind driven generator and less than the preset maximum rotating speed threshold, obtaining an output phase current reference value or an output power reference value of the wind driven generator by searching a rotating speed-power curve table of the wind driven generator in combination with the current rotating speed value of the wind driven generator;
and performing deviation adjustment control on the output of the wind driven generator according to the output phase current reference value or the output power reference value of the wind driven generator.
2. The method according to claim 1, wherein the step S3 includes:
and controlling the duty ratio of a power switch device in the unloading circuit to increase to 100% from zero according to a preset first step length.
3. The method according to claim 1, wherein after the step S3, the method further comprises:
and controlling the conduction of a power switch device in the three-phase bridge type semi-controlled rectifying circuit, and simultaneously carrying out current-limiting control on the output current of the wind driven generator.
4. The method according to claim 3, wherein the controlling the conduction of the power switch device in the three-phase bridge semi-controlled rectification circuit comprises:
and controlling the duty ratio of a power switching device in the three-phase bridge type semi-controlled rectifying circuit to increase to 100% from zero according to a preset second step length.
5. The method according to claim 3 or 4, wherein the current-limiting control of the output current of the wind turbine comprises:
and when the output current of the wind driven generator is judged to exceed the preset limit current value, reducing the duty ratio of a power switch device in the three-phase bridge type semi-controlled rectifying circuit according to a preset third step length so as to limit the output current of the wind driven generator to be continuously increased.
6. The method of claim 5, further comprising:
in the process of carrying out current-limiting control on the output current of the wind driven generator, when the output current of the wind driven generator continuously exceeds a preset current-limiting value within a second preset time period, the electronic brake switch is controlled to be closed.
7. The method of claim 1, further comprising:
in the process of controlling the three-phase bridge type half-controlled rectifying circuit to carry out maximum power tracking control on the output of the wind driven generator, when the voltage of the direct-current bus is detected to be higher than the preset grid-connected switch conducting voltage, the grid-connected switch is controlled to be conducted, and when the voltage of the direct-current bus is detected to be higher than the preset grid-connected voltage, the inverter circuit is controlled to carry out inversion output.
8. The method according to claim 7, wherein the controlling the inverter circuit to perform an inverting output comprises:
carrying out Clark Clarke transformation on the output current of the inverter circuit to obtain an alpha-axis current component i of the output current of the inverter circuit under an alpha-beta two-phase static coordinate systemgαAnd a beta-axis current component igβ；
For the alpha-axis current component igαAnd the beta-axis current component igβCarrying out Park conversion to obtain the alpha-axis current component igαAnd the beta-axis current component igβReactive current i under dq two-phase rotating coordinate systemgdAnd an active current igq；
Comparing the DC bus voltage with a preset valueCarrying out proportional integral operation on the difference value of the reference voltage to obtain an active current instruction value i* gq；
For the reactive current igdAnd a preset reactive current instruction value i* gdThe difference value is subjected to proportional integral operation to obtain a first voltage instruction value u* sd；
For the active current igqAnd the active current command value i* gqThe difference value is subjected to proportional integral operation to obtain a second voltage instruction value u* sq；
For the first voltage command value u* sdAnd the second voltage command value u* sqCarrying out Park inverse transformation to obtain a first controlled quantity u* sαAnd a second control quantity u* sβ；
According to the first control quantity u* sαAnd the second control amount u* sβAnd performing Space Vector Pulse Width Modulation (SVPWM) to generate a driving signal for controlling the on-off of a power switch device in the inverter circuit.
9. The method of claim 8, further comprising:
when the fact that the direct-current bus voltage is continuously smaller than the grid-connected voltage within a third preset duration and the grid-connected power of the wind power generation grid-connected inverter is smaller than a preset minimum grid-connected power is detected, or the fact that the power grid is abnormal is detected, the inverter circuit is controlled to stop inversion output, wherein the grid-connected power is the difference value of the output power of the wind power generator and the power consumed by the unloading circuit.
10. The method of claim 1, wherein the wind power grid-connected inverter further comprises a manual brake switch disposed between the wind generator output and the electronic brake switch for manual braking upon failure or servicing of the electronic brake switch.
11. The method of claim 1, further comprising: when the voltage of the direct current bus is detected to be higher than a preset unloading voltage, the unloading circuit is controlled to unload so as to inhibit the voltage of the direct current bus from rising; the method specifically comprises the following steps:
determining an initial duty cycle according to the following formula:
wherein D is1To initial duty cycle, U3For a predetermined unloading voltage, U4To a preset full off-load voltage, UdcFor the DC bus voltage, a preset complete unloading voltage U4Greater than a predetermined unloading voltage U3；
Adjusting the duty cycle of a power switching device in the unloading circuit to the initial duty cycle;
and controlling the duty ratio of a power switching device in the unloading circuit to be increased to 100% from the initial duty ratio according to a preset fourth step length.
12. The method of claim 11, further comprising: when the unloading duty ratio of the unloading circuit reaches a 100% complete unloading state, if the direct-current bus voltage still shows a rising trend and reaches a preset maximum voltage threshold value, controlling the duty ratio of a power switching device in the three-phase bridge type semi-controlled rectifying circuit to increase from zero according to a preset fifth step length, and simultaneously carrying out current limiting control on the output current of the wind driven generator; and detecting the voltage of the direct current bus in real time, executing braking action if the voltage of the direct current bus still rises to reach a preset braking condition, and disconnecting a power switch device in the three-phase bridge type semi-controlled rectifying circuit if the voltage of the direct current bus drops to or below a preset maximum voltage threshold.
13. A wind power grid-connected inverter, characterized in that the wind power grid-connected inverter comprises a control component for executing the method of any one of claims 1 to 12, the wind power grid-connected inverter further comprises an electronic brake switch, a three-phase bridge semi-controlled rectifying circuit, an unloading circuit, an inverting circuit and a grid-connected switch, the electronic brake switch is connected between the output end of the wind power generator and the input end of the three-phase bridge semi-controlled rectifying circuit, the output end of the three-phase bridge semi-controlled rectifying circuit is connected with the input end of the unloading circuit, the output end of the unloading circuit is connected with a direct current bus, the direct current bus is connected with the direct current side of the inverting circuit, the alternating current side of the inverting circuit is connected with a power grid through the grid-connected switch, and the control component is respectively connected with the electronic brake switch, the, The unloading circuit, the inverter circuit and the grid-connected switch are connected.
14. The wind power generation grid-connected inverter according to claim 13, wherein the three-phase bridge type half-controlled rectification circuit and the unloading circuit are integrally packaged in the same IGBT module, and the inverter circuit is an IPM module.
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| CN201911345576.0A CN111030177B (en) | 2019-12-24 | 2019-12-24 | Wind power generation grid-connected inverter and control method thereof |
| PCT/CN2020/077561 WO2021128584A1 (en) | 2019-12-24 | 2020-03-03 | Wind power generation grid-connected inverter and control method therefor |
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| CN112234644B (en) * | 2020-08-28 | 2024-04-30 | 国网河北省电力有限公司 | Method and system for controlling re-grid-connection of photovoltaic grid-connected power generation system |
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