Voltage sag treatment equipment adopting super capacitor as energy storage deviceTechnical Field
The invention relates to the technical field of electric energy quality, in particular to voltage sag treatment equipment using a super capacitor as an energy storage device.
Background
The voltage sag refers to the phenomenon that the effective value of the power supply voltage suddenly drops and rises again and recovers in a short time, and the international Institute of Electrical and Electronic Engineering (IEEE) defines the voltage sag as the phenomenon that the effective value of the power frequency voltage at a certain point in the power system temporarily drops to 10% -90% of the rated voltage, lasts for 10ms-1min and then recovers to a normal level.
According to the traditional sag treatment scheme comprising a dynamic regulator DVR, an uninterruptible power supply UPS and an AC output voltage sag protector AVSP, an AC power supply technology is adopted as a solution, the AC-DC-AC structural characteristics of a frequency converter are not fully considered, the problems of low conversion efficiency, insufficient protection range, not fast switching time and the like exist, and due to the fact that the AC solution is in a series mode, the reliability of the whole system can be reduced; at present, a scheme of direct current side treatment is adopted, but lead-acid or lead-carbon batteries are mostly adopted for energy storage, a special charging circuit and a special discharging control circuit are required to be arranged, and the service life can be influenced by over-charging and over-discharging.
Disclosure of Invention
In order to solve the defects mentioned in the background art, the invention aims to provide voltage sag treatment equipment using a super capacitor as an energy storage device, and solves the problems of insufficient protection range and short switching time of a voltage sag protector in the prior art.
The purpose of the invention can be realized by the following technical scheme:
the utility model provides an adopt super capacitor as energy memory's voltage sag treatment equipment which characterized in that includes following module:
an energy storage unit: for storing electrical energy;
AC/DC charging unit: the energy storage unit is used for charging the energy storage unit;
a control unit: and the bus voltage is maintained by controlling the energy storage unit to discharge when the voltage is temporarily dropped.
Furthermore, the energy storage unit stores energy by adopting a super capacitor.
Furthermore, the AC/DC charging unit adopts a constant-current voltage-limiting charging method, the first stage of the method adopts larger current to save charging time, and the later stage adopts constant-voltage charging to achieve low-current charging before the charging is finished.
Further, the constant-current voltage-limiting charging method is provided with the highest voltage Umax, and when the voltage exceeds the Umax, constant-voltage floating charging is carried out.
Further, the control method of the control unit is that when the voltage of the alternating current loop drops temporarily, the energy storage unit discharges to maintain the voltage of the direct current bus of the frequency converter, and when the voltage of the alternating current loop recovers, the DC/DC converter stops power output, and the treatment equipment stops running.
Furthermore, the super capacitor is installed in a two-group series connection mode.
Further, the super capacitor is connected with a DC/DC converter for boosting.
Furthermore, when the energy storage unit and the control switch powered by the input power supply are switched on and switched off, the switching-on and switching-off time of one switch lags behind a certain phase angle of the other switch.
Further, the specific operation steps of the system are as follows; the energy storage unit is connected to a direct current bus link of the frequency converter through a diode after being boosted by the voltage sag control device DC/DC, a frequency converter operation signal and a contactor control signal are respectively and directly connected to a distributed control system DCS through the control unit, and when the frequency converter generates voltage sag, the sag control device outputs direct current voltage to keep the frequency converter to continuously operate.
The invention has the beneficial effects that:
1. the invention solves the problems of insufficient protection range and insufficient switching time of the voltage sag protector through direct current side treatment;
2. according to the invention, one of the energy storage unit and the control switch for supplying power to the input power supply lags the other switch by a certain phase, so that two paths of inductive currents are staggered, the ripple current is reduced, and the stability of the device is enhanced.
Drawings
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art to obtain other drawings without creative efforts;
FIG. 1 is a topological diagram of an abatement device system of the present invention;
FIG. 2 is a circuit diagram of the sag control device of the present invention;
fig. 3 is a circuit diagram of the main loop DC/DC of the frequency converter of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, 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 invention.
Example 1
As shown in fig. 1, a voltage sag management device using a super capacitor as an energy storage device includes the following modules: an energy storage unit: for storing electrical energy; AC/DC charging unit: the energy storage unit is used for charging the energy storage unit; a control unit: and the bus voltage is maintained by controlling the energy storage unit to discharge when the voltage is temporarily dropped. After the voltage of the super capacitor is boosted by the voltage sag control device DC/DC, the super capacitor is connected to a direct current bus link of the frequency converter through a diode, a frequency converter operation signal and a contactor control signal are respectively and directly connected to a distributed control system DCS through a control unit, and when the frequency converter generates voltage sag, the sag control device outputs direct current voltage to keep the frequency converter to continuously operate;
furthermore, when the equipment is operated and maintained, the DCS can disconnect the sag control device from the direct-current bus of the frequency converter through the control unit.
Example 2
As shown in fig. 2-3, a voltage sag management device using a super capacitor as an energy storage device includes the following modules: an energy storage unit: for storing electrical energy; AC/DC charging unit: the energy storage unit is used for charging the energy storage unit; a control unit: and the bus voltage is maintained by controlling the energy storage unit to discharge when the voltage is temporarily dropped. The energy storage unit is connected to a direct current bus link of the frequency converter through a diode after being boosted by the voltage sag control device DC/DC, a frequency converter operation signal and a contactor control signal are respectively and directly connected to a distributed control system DCS through the control unit, and when the frequency converter has voltage sag, the sag control device outputs direct current voltage to keep the frequency converter to continuously operate;
furthermore, the energy storage unit stores energy by adopting a super capacitor, the energy storage unit is connected to a direct current bus of the frequency converter after being boosted by the main loop DC/DC converter, and the AC/DC charging unit charges the super capacitor energy storage unit. From the viewpoint of rapidity of charging and limitation of charging current, the AC/DC charging unit adopts a constant-current voltage-limiting charging method. The constant-current voltage-limiting charging method is characterized in that the highest voltage is controlled to be Umax, and constant-voltage floating charging is carried out after the constant-current charging is finished until the super capacitor is fully charged. The advantages of adopting the charging method are: the charging time is saved by adopting larger current in the first stage, and the charging can be carried out by adopting constant voltage charging in the later stage to reach low current before the charging is finished, so that the super capacitor is fully charged, and the influence of high temperature in the super capacitor on the capacity characteristic of the super capacitor can be avoided.
In some disclosures, the system works specifically as follows: when the voltage of the alternating current loop temporarily drops, the voltage of a direct current bus of the frequency converter drops, and when the voltage of the direct current bus is lower than the output voltage of the DC/DC converter, the super capacitor discharges to maintain the voltage of the direct current bus of the frequency converter and ensure the normal operation of the direct current bus; when the voltage of the alternating current loop is recovered, the voltage of the direct current bus of the frequency converter is raised, the DC/DC converter stops power output, and the treatment equipment is quitted from running. The super capacitor adopts two series connection modes, single group voltage direct current is 160V, total voltage direct current is 320V, and the super capacitor is boosted into DC500V through a DC/DC converter.
And the AC rectified DC input voltage Ui is boosted in parallel in a staggered manner through the BOOST. When the switch Q1 is closed, the input power supply supplies energy to the inductor L1, the inductor L1 stores energy, the D1 is reversely biased to be cut off, and the load is supplied with energy by the capacitor. When Q1 is off, diode D1 conducts and the output capacitor and load absorb energy from the inductor and input supply. Q1 and Q2 are conducted in a staggered mode, the period and the duty ratio of each switch are the same, the turn-on moment Q2 lags behind Q1 by Ts/2, each switch controls the corresponding BOOST unit respectively, the input current is the sum of the inductive currents of the two units, therefore, two paths of inductive currents can be staggered, the ripple current is reduced as long as the turn-on time and the turn-off time of the two switches are controlled, the turn-on time and the turn-off time of one switch lag behind the turn-off time of the other switch by a certain phase angle, and the stability of the device is enhanced.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed.