The utility model content
The technical assignment of the technical problems to be solved in the utility model and proposition is that the prior art scheme is improved and improved, and provides a kind of microgrid system with two-way inverter, to stablize the purpose of electrical network.For this reason, the utility model is taked following technical scheme.
A kind of microgrid system with two-way inverter, comprise little electricity generation system, connect little electricity generation system to the net-connected controller of the combining inverter of public electric wire net and the work of control combining inverter, it is characterized in that: described microgrid system also comprises storage battery, connect storage battery to the two-way inverter of public electric wire net, control the stability controller of two-way inverter work, net-connected controller is connected to control combining inverter with combining inverter can export the maximum power of little electricity generation system to public electric wire net, described stability controller is established line voltage and frequency sampling module, to stablize electrical network, described two-way inverter and ac bus also connect stability controller according to line voltage and the two-way inverter work of FREQUENCY CONTROL.This microgrid system is made up of the distributed power station of having complementary functions and two-way inverter.Be chosen on the dc bus still on the ac bus and connect technology and the corresponding energy management strategy that depends on that system constructing uses.If local load DC load is more, then adopts direct current and connect; If local load AC load is more, then adopt to exchange and connect.The technical program proposes energy management control scheme, according to voltage and the frequency of current electrical network at the sagging control of V/F, determine the mode of operation of the two-way inverter of photovoltaic, effectively reduce little electrical network to the impact of electrical network, stablize electrical network, improve Electrical Safety, and the fault emergency capability.
As the further of technique scheme improved and replenish, the utility model also comprises following additional technical feature.
Described two-way inverter connects the microgrid liptinite under little electricity generation system and the storage battery formation isolated island pattern.Microgrid liptinite self band electricity generation system, little electricity generation system can be charge in batteries, or directly power supply, improve the electric network emergency ability, when electrical network broke down, two-way inverter was exported the store electrical energy of electric energy and the storage battery of little electricity generation system, reduced the loss that fault is brought.
Described two-way inverter comprises second electric capacity, the 7th switching tube, first inductance, first diode, first switching tube, the second switch pipe, the 3rd switching tube, the 4th switching tube, the 3rd inductance, the 3rd electric capacity, the 5th switching tube, the 6th switching tube, second inductance, the two ends of described second electric capacity are connected with two outputs of the cell panel of little electricity generation system respectively, one end of first inductance is connected with second electric capacity, one end, the other end links to each other with the source electrode of the 7th switching tube and the positive pole of first diode, the source electrode of the negative pole of first diode and the 5th switching tube, first electric capacity reaches by first switching tube, the second switch pipe, the 3rd switching tube, the inverter bridge that the 4th switching tube is formed connects, one output of inverter bridge links to each other with the 3rd inductance, the other end of the 3rd inductance is connected as inverter first output with the 3rd electric capacity one end, the other end of the 3rd electric capacity is connected as inverter second output with another output of inverter bridge, the source electrode of the drain electrode of described the 5th switching tube and the 6th switching tube, second inductance, one end links to each other, the drain electrode of the 6th switching tube, battery terminal negative, second electric capacity, the drain electrode of the 7th switching tube, first electric capacity, inverter bridge ground connection.
Beneficial effect: the technical program proposes energy management control scheme, according to voltage and the frequency of current electrical network at the sagging control of V/F, determine the mode of operation of the two-way inverter of photovoltaic, effectively reduce little electrical network to the impact of electrical network, stablize electrical network, improve Electrical Safety, and the fault emergency capability.
Embodiment
Below in conjunction with Figure of description the technical solution of the utility model is described in further detail.
The utility model comprises little electricity generation system, connect little electricity generation system to the net-connected controller of the combining inverter of public electric wire net and the work of control combining inverter, described microgrid system also comprises storage battery, connect storage battery to the two-way inverter of public electric wire net, control the stability controller of two-way inverter work, net-connected controller is connected to control combining inverter with combining inverter can export the maximum power of little electricity generation system to public electric wire net, described stability controller is established line voltage and frequency sampling module, stablizing electrical network, described two-way inverter and dc bus also connect or with ac bus and connect stability controller according to line voltage and the two-way inverter work of FREQUENCY CONTROL.
The energy management control of two-way inverter is based upon on the basis of V/F control algolithm.V/F voltage-frequency control is micro power network/exchange and the scoop out core technology of usefulness.Two-way inverter need be by changing frequency to regulate the balance between generating-power consumption-storage in the microgrid system.
Two-way inverter and the mode that connects two kinds of forms are arranged:
(1) dc bus and connecing
(2) ac bus and connecing
Be chosen on the dc bus still on the ac bus and connect technology and the corresponding energy management strategy that depends on that system constructing uses.If local load DC load is more, then adopts direct current and connect.If local load AC load is more, then adopt to exchange and connect.Two-way inverter in the present embodiment and the mode that connects adopt and exchange and connect.
In micro power network, storage battery generally adopts on the ac bus and confluxes during as core component.Two-way inverter is satisfying between AC load and the charge in batteries, carries out energy control and conversion.
Interchange and the pattern that connects connect as shown in Figure 1: among Fig. 1, be followed successively by solar power plant, resident's load, two-way inverter from left to right, produce load, wind energy power plant.Two-way inverter input is connected with little electricity generation system.
Two-way inverter circuit topology block diagram is seen accompanying drawing 2, and two-way inverter comprises second capacitor C
2, the 7th switching tube Q, first inductance L
1, the first diode D
1, the first switching tube Q
1, second switch pipe Q
2, the 3rd switching tube Q
3, the 4th switching tube Q
4, the 3rd inductance L, the 3rd capacitor C
3, the 5th switching tube Q
5, the 6th switching tube Q
6, second inductance L
2, described second capacitor C
2Two ends be connected first inductance L with two outputs of the cell panel of little electricity generation system respectively
1An end be connected with second capacitor C, 2 one ends, the other end links to each other with the source electrode of the 7th switching tube Q and the positive pole of first diode, the negative pole of first diode and the 5th switching tube Q
5Source electrode, first capacitor C
1And by the first switching tube Q
1, second switch pipe Q
2, the 3rd switching tube Q
3, the 4th switching tube Q
4The inverter bridge of forming connects, and an output of inverter bridge links to each other with the 3rd inductance L, the other end of the 3rd inductance L and the 3rd electric capacity
C3One end connects as inverter first output, the 3rd capacitor C
3The other end be connected as inverter second output described the 5th switching tube Q with another output of inverter bridge
5Drain electrode and the 6th switching tube Q
6Source electrode, second inductance L
2One end links to each other, the 6th switching tube Q
6Drain electrode, battery terminal negative, second capacitor C
2, the 7th switching tube Q drain electrode, first capacitor C
1, inverter bridge ground connection.Second capacitor C
2, first capacitor C
1Be respectively PV side equalizing capacitance and dc bus side equalizing capacitance, be mainly used to burning voltage.First inductance L
1, the first diode D
1, the 7th switching tube Q is respectively booster circuit side energy storage inductor, conducting diode and switching tube, it constitutes step-up side main circuit topology.First, second, third and fourth switching tube Q
1, Q
2, Q
3, Q
4Form inverter bridge, it is by the pulsewidth ripple control of triangular carrier modulation output.The 3rd inductance L, the 3rd capacitor C are respectively inductance and the electric capacity of inversion side filter circuit, and it constitutes the LC filter.The LC filter can effectively suppress noise, the interference in the circuit, makes inverter export pure alternating current.Second inductance L
2, the 5th, six switching tube Q
5, Q
6Energy storage inductor and switching tube for storage battery two quadrant DC-DC converter.Two quadrant DC-DC converter is mainly used to the energetic interaction of storage battery.Its circuit topology can either charge, and also can discharge.
Build 3KW photovoltaic off-grid inverter model by circuit topology among Fig. 2.When normal band carried, photovoltaic off-grid inverter BOOST side was operated in constant voltage mode to support DC bus-bar voltage.The voltage reference signal of given different frequency when band carries, the power of actual output sees Table 1.
Table 1 power and frequency change relation
Known by table 1, increase the load end power reduction with frequency.Both relations of being inversely proportional to.
In the micro power network, combining inverter always with the ac bus Frequency Synchronization.In the distributed power source, the operation standard of inverter sees Table 2.
The response of table 2 mains frequency
Determined the operating state of each distributed unit in the microgrid by table 2.
The combining inverter normal operating conditions:
State 1: little mains frequency is greater than 50.5Hz
Little electrical network is not enough to support all loads under this pattern.Public electric wire net or energy storage device support little electrical network internal burden.
State 2: little mains frequency is between 50.2Hz and 50.5Hz
The combining inverter operation that does not conform to index was stopped transport after 2 minutes.
State 3: little mains frequency is between 49.5Hz and 50.2Hz
Under this pattern, the inner distributed unit of little electrical network is normally moved.The electric energy that its load is sent by little electrical network inside is born the combining inverter operate as normal.
State 4: little mains frequency is at 48Hz and 49.5Hz
After the operate as normal 10 minutes, the part combining inverter is out of service in little electrical network, part combining inverter operate as normal.
State 5: little mains frequency is less than 48Hz
Close down combining inverter fast.
For guaranteeing that device security normally moves in little electrical network, two-way inverter is by following control mode operation energy management control strategy.
State 1: little mains frequency is less than 49.5Hz
This moment, mains frequency was low excessively.For guaranteeing the fail safe of two-way inverter, two-way inverter is not worked.
State 2: little mains frequency is between normal 49.5Hz and 50Hz
This moment, two-way inverter belonged to normal working range.The electrical network output frequency needs accurate matched load, and for guaranteeing frequency retrieval to the 50Hz of standard, the big electric current of two-way inverter energy storage side fills energy.Two-way inverter participates in mains frequency and regulates, and absorbs unnecessary gaining merit in the electrical network according to electrical network to the batteries to store energy control model.But two-way inverter was not worked when storage battery was full of.
State 3: little mains frequency is between normal 50Hz and 50.2Hz
This moment, two-way inverter did not belong to normal working range.But be assurance accumulator electric-quantity abundance, and two-way inverter does not influence grid stability.So the energy storage side is under the situation of electric energy deficiency, the little electric current of storage battery fills energy.After being full of, two-way inverter is not worked.
State 4: little mains frequency is between 50Hz and 50.5Hz
If equipment is sensitive equipment, two-way inverter of this stage can be controlled the network relay disconnection and be operated in band and carry a pattern.Mode of operation that also can selection mode 3.
State 5: little mains frequency is higher than 50.5Hz
Two-way inverter disconnects electrical network, and two-way inverter begins to support the line voltage of micro power network.Frequency when two-way inverter supports electrical network is greater than 50.7 the time, and two-way inverter quits work.
Two-way inverter V/F voltage-frequency control block diagram is seen accompanying drawing 3.V wherein
InvWith I
InvBe respectively voltage and the electric current of inverter outlet side.Calculate current gaining merit with idle by power measurement module, V/F droop characteristic power controller determines voltage and the frequency of given reference signal.Voltage loop PID control is used for steady load voltage.Interior ring adopts pure proportional controller for guaranteeing enough real-times.Control signal is through PWM module, control switch pipe break-make.State transition diagram under the sensitive loads pattern is seen accompanying drawing 4, and the state transition diagram under the general load model is seen accompanying drawing 5.Wherein F is mains frequency, and F1 is the instruction frequency of two-way inverter inside, and SOC is the state-of-charge of storage battery, the type selecting of concrete numerical basis storage battery.
A kind of microgrid system with two-way inverter shown in above Fig. 1-5 is specific embodiment of the utility model; the utility model outstanding substantive distinguishing features and obvious improvement have been embodied; can be according to the use needs of reality; under enlightenment of the present utility model; it is carried out the equivalent modifications of aspects such as shape, structure, all at the row of the protection range of this programme.