CN106786797B - A kind of control method for the microgrid inverter improving microgrid busbar voltage quality - Google Patents
A kind of control method for the microgrid inverter improving microgrid busbar voltage quality Download PDFInfo
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- CN106786797B CN106786797B CN201611225599.4A CN201611225599A CN106786797B CN 106786797 B CN106786797 B CN 106786797B CN 201611225599 A CN201611225599 A CN 201611225599A CN 106786797 B CN106786797 B CN 106786797B
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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
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
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Abstract
The invention discloses a kind of control methods of microgrid inverter for improving microgrid busbar voltage quality, it is characterized in that: the microgrid inverter is to control to work independently by itself to realize power distribution between the improvement of microgrid busbar voltage quality and unit；And the scheduling of upper layer center management system can be received, microgrid inverter output voltage is adjusted according to the dispatch command of tension management system, realizes that busbar voltage control and quality of voltage improve.The present invention participates in microgrid busbar voltage quality using microgrid inverter and controls, by controlling inverter output impedance absorbing load harmonic current, can not only reduce microgrid dedicated for power quality improve power electronic equipment investment, but also due to microgrid inverter installation dispersibility to control it is more flexible.
Description
Technical field
The present invention relates to a kind of control methods of microgrid inverter for improving microgrid busbar voltage quality.
Background technique
Microgrid as one can both be incorporated into the power networks also can the independently operated compact electrical generating systems of off-grid, net internal loading form
With very big randomness and diversity.And a large amount of civilian and commercial plants have power electronic devices interface in netting, and make
It obtains load and is characterized primarily by nonlinear characteristic.Harmonic current caused by nonlinear load is in line impedance and inverter output impedance
Upper generation harmonic wave pressure drop, will lead to the distortion of busbar voltage, influence bus load supplying quality, possibly even cause when serious be
System unstability.To improve microgrid power supply quality, a kind of common method is to install power quality additional to improve device, such as active filter.So
And the power load type and capacity on micro-capacitance sensor median generatrix have very big uncertainty, this gives power quality controlling device
On-position selection bring difficulty.Ensure that load power quality just needs a large amount of power quality adjusting device, this
Micro-grid system construction and operating cost can undoubtedly be significantly greatly increased.Increase utility power quality control function by microgrid inverter, it can
The local compensation for being easily carried out harmonic wave is administered.Therefore, inverter is made to have harmonics restraint function by microgrid inverter control
Can, to the investment for improving power electronic equipment in reduction microgrid dedicated for power quality, and improvement micro-capacitance sensor busbar voltage
Quality advance system reliability has important theory and realistic meaning.Microgrid busbar voltage controls under the conditions of nonlinear load,
The control mode of multi-resonant controller is used mainly under rest frame.It is controlled for the harmonic component of each frequency
System, every control for increasing a frequency harmonic component, just needs to increase a resonant controller, and all inverters both participate in
The control of quality of voltage.This control program, all inverters both participate in the control of harmonic voltage, and inverter participates in quality of voltage
Control is without selectivity.However, in micro-capacitance sensor and not all inverter be suitable for participate in quality of voltage adjust, work as gird-connected inverter
When itself full capacity exports, then it is difficult to participate in the control of quality of voltage.In addition, every increase first harmonic voltage control, just needs to increase
Add a resonant controller, contravarianter voltage controller is complicated.
Summary of the invention
The present invention be to avoid above-mentioned deficiency of the prior art, provide a kind of control of system flexibly, control method
Improve the control method of the microgrid inverter of microgrid busbar voltage quality under succinct nonlinear load.
The present invention adopts the following technical scheme that in order to solve the technical problem
The characteristics of control method of the microgrid inverter of present invention improvement microgrid busbar voltage quality, is: the microgrid inversion
Device is to control to work independently by itself to realize power distribution between the improvement of microgrid busbar voltage quality and microgrid inverter；
And the scheduling of upper layer center management system can be received, it is defeated to adjust microgrid inverter according to the dispatch command of upper layer center management system
Voltage out realizes that busbar voltage control and quality of voltage improve.
The characteristics of control method of the microgrid inverter of present invention improvement microgrid busbar voltage quality, lies also in: inverse in microgrid
The voltage control loop for becoming device increases harmonic impedance control, by simulating harmonic wave negative impedance absorbing load harmonic current, improves microgrid
Busbar voltage quality.
The characteristics of control method of the microgrid inverter of present invention improvement microgrid busbar voltage quality, lies also in: real-time monitoring
Microgrid inverter exports electric current, the harmonic components of microgrid inverter output electric current is extracted, according to virtual impedance and line impedance meter
It calculates and obtains harmonic reference voltage, by the harmonic reference voltage superposition to fundamental wave reference voltage, and then control inverter output electricity
Pressure, makes inverter have negative harmonic impedance characteristic, improves busbar voltage quality with this；Meanwhile in the microgrid inverter receiving
The size of the scheduling of layer managing system, real time modifying virtual impedance and line impedance is to adapt to system difference operating condition.
The characteristics of control method of the microgrid inverter of present invention improvement microgrid busbar voltage quality, lies also in: the microgrid
The control algolithm of inverter output voltage is:
It is calculated using sagging control and obtains microgrid inverter fundamental wave reference voltage ureff；
By feeder current ioLow-pass filtered device LPF extracts fundamental current io1, by the fundamental current io1Multiplied by virtual
Impedance ZvObtain virtual impedance voltage uv；
By feeder current ioIt is extracted through harmonic wave and obtains harmonic current components iom, m=6n ± 1, n=1,2,3 ..., it will be described humorous
Wave current component iomWith m subharmonic reactance XmIt is multiplied and obtains m subharmonic voltage reference value urefm, m=6n ± 1；
By feeder current ioFundametal compoment, which is filtered out, through high-pass filter HPF obtains harmonic current ih, by the harmonic current ih
Multiplied by harmonic wave resistance RhObtain harmonic wave resistive reference voltage value urefR；
Then, harmonic impedance voltage reference value urefhAre as follows:
Wherein, virtual impedance Zv, harmonic compensation number m, harmonic wave reactance XmAnd harmonic wave resistance RhReceive upper layer central management
The scheduling of system, being capable of online modification.
The characteristics of control method of the microgrid inverter of present invention improvement microgrid busbar voltage quality, lies also in:
It is calculated by formula (1) and obtains microgrid inverter with reference to given voltage uref:
uref=ureff+uv+urefh (1)
The microgrid inverter is referred into given voltage urefReference voltage ac-dc axis point under rotation transformation to rotating coordinate system
AmountBy microgrid inverter output voltage uoRotation transformation is voltage ac-dc axis component u under rotating coordinate systemodq, then voltage error
ΔudqAre as follows:
By the voltage error Δ udqFundamental current reference value is obtained using the fundamental wave controller characterized by formula (2)
(ifdq)k:
(ifdq)k=a0(Δudq)k+a1(Δudq)k-1-b1(ifdq)k-1 (2)
In formula (2), k is kth time sampling instant, and k-1 is -1 sampling instant of kth, b1=-1, kvPFor fundamental wave controller proportionality coefficient, kvIFor fundamental wave controller integral coefficient, TsFor the sampling period.
The voltage error Δ udqM subharmonic current reference value is obtained via the m subharmonic controller that formula (3) characterize
(imdq)k:
(imdq)k=c1(Δudq)k+c2(Δudq)k-2-d1(imdq)k-1-d2(imdq)k-2 (3)
In formula (3):
Wherein, m is corresponding each overtone order, kRhFor harmonic controller proportionality coefficient, ωcFor harmonic controller cutoff frequency
Rate, ω0For fundamental voltage frequency；
Based on individual harmonic current reference value (imdq)kIt calculates and obtains harmonic current reference value (ihdq)kAre as follows:
Then have: current reference valueAre as follows:
By microgrid inverter electric current iLElectric current ac-dc axis electric current i under rotation transformation to rotating coordinate systemLdq, by current reference
ValueWith electric current ac-dc axis electric current i under rotating coordinate systemLdqIt is poor to make, then through current controller output voltage reference value Udq, by institute
State voltage reference value UdqThrough u under rotation transformation to rest frameabc, with the uabcSPWM modulation is participated in, microgrid inversion is controlled
The on-off of device power switch tube.
Microgrid busbar voltage controls under the conditions of the present invention is directed to nonlinear load, gives whether inverter participates in voltage matter
Amount control is controllable, participates in harmonic voltage number improves optional system control method, and harmonic controling is calculated under single coordinate transform
Method；Its microgrid inverter can not only receive the control of tension management system call, but also can be detached from top level control independent operating.Based on list
The control of coordinate transform resonance, the control to two order harmonic components may be implemented in a resonant controller, and can receive upper layer
Scheduling participates in specified subharmonic voltage control；Compared with the prior art, the invention has the advantages that:
1, present system can reduce the investment of dedicated microgrid electric energy governing device；
2, present system is more flexible in terms of busbar voltage quality control；
3, the micro-grid inverter voltage control algolithm of present system is more succinct.
Detailed description of the invention
Fig. 1 is micro-grid system structural block diagram according to the present invention
Fig. 2 is busbar voltage System control structures schematic diagram of the present invention；
Fig. 3 is control method flow chart of the present invention；
Specific embodiment
Referring to Fig. 1, in the present embodiment micro-grid system include several distributed generation units, it is linear and non-linear negative
Load, driving circuit, over-sampling modulate circuit and protection circuit, are connected in parallel between several distributed generation units, including
Main circuit, local controller are connected to common bus by feeder line；Main circuit includes that sequentially connected micro- source, three phase full bridge are inverse
Become device, filter inductance L, filter capacitor C, feeder line, three-phase full-bridge inverter circuit includes six power switch tubes, and common bus is also
Connect linear and nonlinear load；Several distributed generation units, linear and nonlinear load form independent micro-capacitance sensor, system
It further include the communication system for connecting local controller and microgrid central controller.
The control method for improving the microgrid inverter of microgrid busbar voltage quality in the present embodiment is: microgrid inverter is logical
It crosses itself control autonomous working and realizes power distribution between the improvement of microgrid busbar voltage quality and microgrid inverter；And it can
Receive the scheduling of upper layer center management system, microgrid inverter output electricity is adjusted according to the dispatch command of upper layer center management system
Pressure realizes that busbar voltage control and quality of voltage improve.
Increase harmonic impedance control in the voltage control loop of microgrid inverter, it is humorous by simulation harmonic wave negative impedance absorbing load
Wave electric current improves microgrid busbar voltage quality.By extracting harmonic current on feeder line, line impedance and virtual impedance, meter are considered
Corresponding subharmonic voltage reference value is sought in calculation, and control microgrid inverter output voltage realizes changing for microgrid busbar voltage quality indirectly
It is kind.
Specific implementation by real-time monitoring microgrid inverter export electric current, extract microgrid inverter output electric current harmonic wave at
Point, it is calculated according to virtual impedance and line impedance and obtains harmonic reference voltage, by harmonic reference voltage superposition to fundamental wave with reference to electricity
Pressure, and then inverter output voltage is controlled, so that inverter is had negative harmonic impedance characteristic, busbar voltage quality is improved with this；Together
When, microgrid inverter can receive the manage and dispatch of upper layer central controller, real time modifying virtual impedance and line impedance it is big
It is small to adapt to system difference operating condition.Upper layer central controller can be online to determine modification according to system busbar voltage condition
Microgrid inverter participates in the variables such as harmonic voltage coefficient, each frequency harmonic impedance size, virtual impedance size, this makes system control
System is more flexible, is suitable for the micro-grid system of different networking structures and does not have to operating condition.The control flow of microgrid inverter
As shown in Figure 3.
It for the control of harmonic current, is generally realized under rest frame, uses a controller for every subharmonic.
By will be realized under harmonic conversion to rotating coordinate system in the present invention, since adjacent subharmonic is characterized as together under rotating coordinate system
One frequency AC amount, a controller can realize the control to two frequency harmonic components.Compared with being controlled under rest frame,
The use of half harmonic controller can be reduced, controller is more succinct, operand is small.
The control algolithm of microgrid inverter output voltage is:
It is calculated using sagging control and obtains inverter fundamental wave reference voltage ureff；
By feeder current ioLow-pass filtered device LPF extracts fundamental current io1, by fundamental current io1Multiplied by virtual impedance
ZvObtain virtual impedance voltage uv；
By feeder current ioIt is extracted through harmonic wave and obtains harmonic current components iom, m=6n ± 1, n=1,2,3 ..., it will be described humorous
Wave current component iomWith m subharmonic reactance XmIt is multiplied and obtains m subharmonic voltage reference value urefm, m=6n ± 1；
By feeder current ioFundametal compoment, which is filtered out, through high-pass filter obtains harmonic current ih, by harmonic current ihMultiplied by humorous
Wave resistance RhObtain harmonic wave resistive reference voltage value urefR；
Then, harmonic impedance voltage reference value urefhAre as follows:
Wherein, virtual impedance Zv, harmonic compensation number m, harmonic wave reactance XmAnd harmonic wave resistance RhReceive upper layer central management
The scheduling of system, being capable of online modification.
It is to carry out in specific implementation as follows:
It is calculated by formula (1) and obtains microgrid inverter with reference to given voltage uref:
uref=ureff+uv+urefh (1)
Microgrid inverter is referred into given voltage urefReference voltage ac-dc axis component under rotation transformation to rotating coordinate systemBy microgrid inverter output voltage uoRotation transformation is voltage ac-dc axis component u under rotating coordinate systemodq, then voltage error Δ
udqAre as follows:
By the voltage error Δ udqFundamental current reference value is obtained using the fundamental wave controller characterized by formula (2)
(ifdq)k:
(ifdq)k=a0(Δudq)k+a1(Δudq)k-1-b1(ifdq)k-1 (2)
In formula (2), k is kth time sampling instant, and k-1 is -1 sampling instant of kth, b1=-1, kvPFor fundamental wave controller proportionality coefficient, kvIFor fundamental wave controller integral coefficient, TsFor the sampling period.
Voltage error Δ udqM subharmonic current reference value (i is obtained via the m subharmonic controller that formula (3) characterizemdq)k:
(imdq)k=c1(Δudq)k+c2(Δudq)k-2-d1(imdq)k-1-d2(imdq)k-2 (3)
In formula (3):
Wherein, m is corresponding each overtone order, kRhFor harmonic controller proportionality coefficient, ωcFor harmonic controller cutoff frequency
Rate, ω0For fundamental voltage frequency；
Based on individual harmonic current reference value (imdq)kIt calculates and obtains harmonic current reference value (ihdq)kAre as follows:
Then have: current reference valueAre as follows:
By microgrid inverter electric current iLElectric current ac-dc axis electric current i under rotation transformation to rotating coordinate systemLdq, by current reference
ValueWith electric current ac-dc axis electric current i under rotating coordinate systemLdqIt is poor to make, then through current controller output voltage reference value Udq, will be electric
Press reference value UdqThrough u under rotation transformation to rest frameabc, with uabcSPWM modulation is participated in, control microgrid inverter power is opened
Close the on-off of pipe.
Claims (2)
1. a kind of control method for the microgrid inverter for improving microgrid busbar voltage quality, it is characterized in that: the microgrid inverter
It is to control to work independently by itself to realize power distribution between the improvement of microgrid busbar voltage quality and microgrid inverter；And
It can receive the scheduling of upper layer center management system, microgrid inverter output is adjusted according to the dispatch command of upper layer center management system
Voltage realizes that busbar voltage control and quality of voltage improve；Increase harmonic impedance control in the voltage control loop of microgrid inverter,
By simulating harmonic wave negative impedance absorbing load harmonic current, improve microgrid busbar voltage quality；
The control algolithm of the microgrid inverter output voltage is:
It is calculated using sagging control and obtains microgrid inverter fundamental wave reference voltage ureff；
By feeder current ioLow-pass filtered device LPF extracts fundamental current io1, by the fundamental current io1Multiplied by virtual impedance
ZvObtain virtual impedance voltage uv；
By feeder current ioIt is extracted through harmonic wave and obtains harmonic current components iom, m=6n ± 1, n=1,2,3..., by the harmonic wave
Current component iomWith m subharmonic reactance XmIt is multiplied and obtains m subharmonic voltage reference value urefm, m=6n ± 1；
By feeder current ioFundametal compoment, which is filtered out, through high-pass filter HPF obtains harmonic current ih, by the harmonic current ihMultiplied by
Harmonic wave resistance RhObtain harmonic wave resistive reference voltage value urefR；
Then, harmonic impedance voltage reference value urefhAre as follows:
Wherein, virtual impedance Zv, harmonic compensation number m, harmonic wave reactance XmAnd harmonic wave resistance RhReceive upper layer center management system
Scheduling, being capable of online modification.
2. the control method of the microgrid inverter according to claim 1 for improving microgrid busbar voltage quality, it is characterized in that:
It is calculated by formula (1) and obtains microgrid inverter with reference to given voltage uref:
uref=ureff+uv+urefh (1)
The microgrid inverter is referred into given voltage urefReference voltage ac-dc axis component under rotation transformation to rotating coordinate systemBy microgrid inverter output voltage uoRotation transformation is voltage ac-dc axis component u under rotating coordinate systemodq, then voltage error Δ
udqAre as follows:
By the voltage error Δ udqFundamental current reference value (i is obtained using the fundamental wave controller characterized by formula (2)fdq)k:
(ifdq)k=a0(Δudq)k+a1(Δudq)k-1-b1(ifdq)k-1 (2)
In formula (2), k is kth time sampling instant, and k-1 is -1 sampling instant of kth, b1=-1, kvPFor fundamental wave controller proportionality coefficient, kvIFor fundamental wave controller integral coefficient, TsFor the sampling period；
The voltage error Δ udqM subharmonic current reference value (i is obtained via the m subharmonic controller that formula (3) characterizemdq)k:
(imdq)k=c1(Δudq)k+c2(Δudq)k-2-d1(imdq)k-1-d2(imdq)k-2 (3)
In formula (3):
Wherein, m is corresponding each overtone order, kRhFor harmonic controller proportionality coefficient, ωcFor harmonic controller cutoff frequency,
ω0For fundamental voltage frequency；
Based on individual harmonic current reference value (imdq)kIt calculates and obtains harmonic current reference value (ihdq)kAre as follows:
Then have: current reference valueAre as follows:
By microgrid inverter electric current iLElectric current ac-dc axis electric current i under rotation transformation to rotating coordinate systemLdq, by current reference value
With electric current ac-dc axis electric current i under rotating coordinate systemLdqIt is poor to make, then through current controller output voltage reference value Udq, by the voltage
Reference value UdqThrough u under rotation transformation to rest frameabc, with the uabcSPWM modulation is participated in, microgrid inverter power is controlled
The on-off of switching tube.
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| CN110323783B (en) * | 2019-07-24 | 2021-01-08 | 阳光电源股份有限公司 | Photovoltaic grid-connected inverter and control method thereof |
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