Utility model content
The purpose of this utility model is, it is provided that a kind of energy storage off-network inverter improve uninterrupted power supply power factor be
System, the technical problem unstable to solve the power supply unit powering load of prior art, and improve under mains-supplied pattern
The power factor of load.
A kind of energy storage off-network inverter improves the system of uninterrupted power supply power factor, including:
One first power supply branch road, including a mains-supplied unit, described mains-supplied unit passes through one first switch element
Controllably to a load supplying;
One second power supply branch road, with described first power supply branch circuit parallel connection in the two ends of described load, described second power supply
Connect an inverter unit on road, described inverter unit for a DC input voitage is converted to ac output voltage with to
Described load supplying, and
Described inverter unit, when the first duty, individually exports constant voltage and frequency to described load;
Described inverter unit is when the second duty, by controlling output voltage and the institute of described inverter unit
State the phase place angle between the output voltage of inverter unit and the output voltage of mains-supplied unit, adjust described first and supply
The power-factor cos δ, δ of electricity branch road represents the output voltage V of inverter unitcElectric current I with mains-supplied unitgBetween folder
Angle.
Preferably, described inverter unit is controlled by a second switch unit being series in described second power supply branch road
System ground is to described load supplying.
Preferably, described first switch element is relay switch.
Preferably, described inverter unit is single-phase energy storage off-network inverter or three-phase energy storage inverter.
A kind of energy storage off-network inverter improves the method for uninterrupted power supply power factor, based on improving energy storage off-network inverter
The system of uninterrupted power supply, described method includes:
Step 1, it is judged that described mains-supplied unit the most normally works;If it is, perform step 2, if it does not, perform step
Rapid 3;
Step 2, closes second switch unit, described mains-supplied unit and described inverter unit simultaneously to described load
Power supply, and by the output voltage of the described inverter unit of control and the output voltage of described inverter unit and described civil power
Phase place angle between the output voltage of power supply unit, thus adjust the power-factor cos δ, wherein δ of described first power supply branch road
Represent the output voltage V of inverter unitcOutput electric current I with mains-supplied unitgBetween angle;
Step 3, disconnects the first switch element, and described inverter unit individually exports constant voltage and frequency to described load
Rate.
Preferably, by the output voltage of described mains-supplied unit is carried out phase-locked by the way of, control described inversion
Between the output voltage of the output voltage of device unit and the output voltage of described inverter unit and described mains-supplied unit
Phase place angle.
Preferably, described phase-locked method includes:
Wherein, VcRepresenting the output voltage of inverter unit, L1 is the inductance value of inductance in described first power supply branch road,
iload_1Represent load current iloadPositive sequence fundamental current, VgRepresenting the output voltage of mains-supplied unit, α represents VgWith VcIt
Between angle;
The V that described inverter unit is obtained according to formula (1), (2)cAnd the output electricity that α is to described mains-supplied unit
It is pressed into line trace, and on the basis of phase-locked, realize VcAnd VgPhase α.
Preferably, described step 3 also includes:
When described mains-supplied cell operation exception, disconnect the first switch element, after its normally work, described inversion
Device unit continues to carry out phase-locked to described mains-supplied unit.
This utility model describes a kind of method and system improving energy storage off-network inverter uninterrupted power supply, when civil power just
When often working, energy storage off-network inverter improves electrical network by controlling the phase place angle between its output voltage and itself and civil power
Power factor;When city's electrical anomaly, energy storage off-network inverter it is individually for load supplying, and exports constant voltage and frequency
Rate, it is achieved the uninterrupted power supply to load, improves load supplying reliability.
Detailed description of the invention
A kind of energy storage off-network inverter of the present utility model improves the system of uninterrupted power supply power factor, including:
One first power supply branch road, including a mains-supplied unit, mains-supplied unit is controlled by one first switch element
System ground is to a load supplying;
One second power supply branch road, with the first power supply branch circuit parallel connection in the two ends of load, the second power supply branch road connects one inverse
Become device unit, inverter unit for a DC input voitage being converted to ac output voltage to power to the load, and
Inverter unit, when the first duty, individually exports constant voltage and frequency to load;
Inverter unit is when the second duty, by controlling output voltage and the inverter unit of inverter unit
Output voltage and the output voltage of mains-supplied unit between phase place angle, adjust the power factor of the first power supply branch road
Cos δ, δ represent the output voltage V of inverter unitcElectric current I with mains-supplied unitgBetween angle.
As it is shown in figure 1, specifically, the first power supply branch road is mains circuit, including a mains-supplied unit and the first switch
K1, the voltage swing at mains-supplied unit two ends is Vg;Second power supply branch road is the operating circuit of inverter unit, this inverter
The output voltage of unit outfan is Vc。
When mains circuit and inverter unit the most normally work, Guan Bi the first switch K1 and second switch K2, now, inverse
Becoming device unit and be in the second duty, inverter is by controlling VcAnd VgBetween phase place angle α improve the merit of whole electrical network
Rate factor cos δ, improves the utilization ratio of electric energy.When mains circuit occurs abnormal, inverter unit is in another work shape
State, is individually for load supplying by inverter unit, exports constant voltage and frequency for it, it is achieved that the uninterrupted confession to load
Electricity, improves load supplying reliability.And the first switch K1 connected can automatically cut off when mains circuit appearance is abnormal
Mains circuit, it is ensured that the safety of circuit.
Preferred embodiment, the first power supply branch road also includes one first inductance to this utility model, and the first inductance is series at
On first power supply branch road.
Specifically, connect an inductance L1 in mains circuit, it is possible to ensures that inverter can adjust civil power output voltage and city
Phase place angle between electricity output electric current.
This utility model preferred embodiment, inverter unit by one be series in the second power supply branch road second open
Close unit controllably to power to the load.
Specifically, connect a second switch K2 with inverter unit, when preventing inverter unit from occurring abnormal, automatically cuts off
The work branch of inverter, it is ensured that the safety of circuit.
Preferred embodiment, the first switch element is relay switch to this utility model.
Relay switch plays overcurrent protection, the effect of overvoltage protection, belongs to a kind of switch automatically, when the electric current in civil power
Or voltage excessive time, relay switch can automatic trip, disconnect place circuit, prevent circuit from damaging further.
Preferred embodiment, inverter unit is single-phase energy storage off-network inverter or three-phase energy storage inversion to this utility model
Device.
A kind of method improving energy storage off-network inverter uninterrupted power supply, based on one improve energy storage off-network inverter not between
The system of cut-off electricity, including:
Step 1, it is judged that mains-supplied unit the most normally works;If it is, perform step 2, if it does not, perform step 3;
Step 2, closes second switch unit, and mains-supplied unit and inverter unit power to the load simultaneously, and pass through
Control between output voltage and the output voltage of the output voltage of inverter unit and mains-supplied unit of inverter unit
Phase place angle, thus adjust the power-factor cos δ of the first power supply branch road, wherein δ represents the output voltage V of inverter unitc
Output electric current I with mains-supplied unitgBetween angle;
Step 3, disconnects the first switch element, and inverter unit individually exports constant voltage and frequency to load.
Specifically, when mains circuit normally works, the first switch K1 and second switch K2 closes, and loads by civil power electricity
Road powers;And by controlling VcAnd VcWith VgBetween angle α, control δ, at this moment load by mains circuit and inverter list
Unit powers simultaneously, simultaneously works as improving the effect of power factor of electric network.When mains circuit occurs abnormal, the first switch K1 breaks
Opening, inverter unit individually exports constant voltage and frequency to load, so that load obtains lasting voltage, steady load
Work.This utility model preferred embodiment, by the output voltage of mains-supplied unit is carried out phase-locked on the basis of, come
Control between output voltage and the output voltage of the output voltage of inverter unit and mains-supplied unit of inverter unit
Phase place angle.
Specifically, phase-locked is exactly the phase and frequency of a certain another signal of signal trace so that with another signal
Phase place keeps synchronizing.As in figure 2 it is shown, when the phase place angle α of the output voltage of inverter unit and two voltages keep constant after,
Voltage vector difference DELTA V of mains-supplied unit and inverter also immobilizes, and this makes it possible to obtain a fixing civil power and supplies
Phase place angle δ between output voltage and the output electric current of mains-supplied unit of electric unit, thus obtain stable cos δ-value,
Namely obtain the power factor of stable civil power.And power factor is to weigh a coefficient of electrical equipment efficiency height, generation
The table load capacity size of electrical network, power factor is low, illustrates that circuit is big for the reactive power of alternating magnetic field conversion, thus drops
The low utilization rate of equipment, adds line powering loss.
Preferred embodiment, described phase-locked mode includes this utility model:
Wherein, VcRepresenting the output voltage of inverter unit, L1 is the inductance value of inductance, i in the first power supply branch roadload_1
Represent load current iloadPositive sequence fundamental current, VgRepresenting the output voltage of mains-supplied unit, α represents VgWith VcBetween
Angle;
The V that inverter unit is obtained according to formula (1), (2)cAnd α the output voltage of mains-supplied unit is carried out with
Track, and on the basis of phase-locked, realize VcAnd VgPhase α.
The concrete derivation in formula (1), (2) is as follows:
Mains-supplied unit is powered to the load with inverter parallel jointly by the inductance L1 connected with mains-supplied unit,
Wherein the output of mains-supplied unit is:
Pg=VcIgCos θ=VcIgsinβ (3)
And the electric current that mains-supplied unit flows to load by inductance L1 is:
Ig=Δ V/ (ω L1) (4)
Then mains-supplied unit output is rewritten as:
Pg=VcΔVsinβ/(ωL1) (5)
See the vectogram in Fig. 2, have according to sine:
Formula (6) is brought into formula (5) obtain mains-supplied unit output flow to load power:
By formula (7) it is recognised that work as the phase place of the output voltage of the advanced inverter of voltage-phase of mains-supplied unit,
Mains-supplied unit provides energy to load,In interval, mains-supplied unit increases along with α to the energy of load offer
Add and increase;In identical α angle, inductance L1 is the least, and the energy that mains-supplied unit provides to load is the biggest.
If the sinusoidal wave form that the output voltage of mains-supplied unit is a standard, then the voltage at inductance L1 two ends is VL1
(t)=Vgsin(ωt)-VcSin (ω t-α), flows through the electric current I of L1g(t) be:
Ig(t)=IgSin (ω t-δ) (8) can be derived from by above formula:
From (9), (10) two formulas it can be seen that owing to the output voltage of mains-supplied unit is unmodifiable, for terrible
Desired electric current on L1, can only be by regulating the output voltage amplitude V of invertercRealize with phase place angle α.
To load current iloadCarrying out discrete Fourier transform (DFT), can obtain its positive sequence fundamental current comprised is iload_1。
When mains-supplied unit and inverter the most normally work, in order to ensure that civil power power factor is preferable, now civil power passes through inductance
L1 gives the supply current I of loadg=iload_1Time, the power factor of electrical network is cos δ.
To this end, work as the i obtaining givingload_1During with δ, from formula (9), (10) available above-mentioned formula (1), (2).
From formula (1), (2) are it can be seen that for the ideal current on we inductance L1 to be followed the tracks of, can calculate and want
The voltage followed the tracks of.Wherein δ is setting value, and the δ of setting is the least, and raising power factor of electric network cos δ effect is the biggest, exports simultaneously
Power is the biggest.
Above-mentioned embodiment is by adjusting the output voltage V of invertercWith this output voltage VcDefeated with mains-supplied unit
Go out voltage VcBetween phase place angle α, thus control the power factor of inverter system, it is achieved the uninterrupted power supply of load, carry
High load supplying reliability.
Preferred embodiment, step 3 also includes this utility model: when mains-supplied cell operation exception, disconnects the
One switch element, after its normally work, inverter unit continues to carry out phase-locked to mains-supplied unit.
Specifically, when mains-supplied unit occur abnormal can not normally time, in order to guarantee to carry out to load constantly
Power supply, when after mains-supplied unit power-off, the first switch K1 disconnects, inverter unit continue the voltage fixing to load conveying and
Electric current.Until mains-supplied unit recovers normal work, inverter unit continues to start to perform from step 1, and to mains-supplied
The output voltage of unit carries out phase-locked, makes mains-supplied unit and inverter unit be powered load simultaneously.
The foregoing is only this utility model preferred embodiment, not thereby limit embodiment of the present utility model and
Protection domain, to those skilled in the art, it should in can appreciate that all utilization this utility model description and diagram
Hold the scheme obtained by the equivalent made and obvious change, all should be included in protection model of the present utility model
In enclosing.