CN204720986U - The compound circuit of a kind of integrated rectification, active power filtering and energy back braking function - Google Patents

Abstract

The utility model discloses a kind of compound circuit being integrated with the functions such as rectification, active power filtering and energy back braking, comprise rectification unit, active power filtering and reactive compensation unit, clamp circuit, rectification unit is directly connected at AC with active power filtering and reactive compensation unit, and connected in DC side by clamp circuit, clamp circuit is connected to active power filtering and between reactive compensation unit and DC bus, for energy provides loop from deceleration loading through active power filtering unit feedback grid.The utility model can compensate preferably to the harmonic current in drilling platforms electrical network, and also solve the over-voltage protection produced when winch declines, feedback load braking energy is to electrical network, and energy-saving efficiency is high.

Description

The compound circuit of a kind of integrated rectification, active power filtering and energy back braking function

Technical field

The utility model relates to a kind of (also comprise other and promote class load, hoist engine load etc.) rectification for oil drilling platform, active power filtering and energy back braking circuit, belongs to power harmonic suppression and energy back braking technology field.

Background technology

At present, China uses electric drive rig in a large number in petroleum engineering, and oil-well rig system its power disposition usual is mainly provided by diesel generating set or public electric wire net.The non-linear electronic devices a large amount of when using public electric wire net to power is as the use of inverter, rectifier and various Switching Power Supply, make to there is a large amount of harmonic waves in 600V network system, thus harmful effect is brought to other power consumption equipment (such as circuit, generator and well site illumination) on 600V electrical network, the humorous reactive loss that involves strengthens.At present conventional harmonic suppressing method is the harmonic wave that adopts Active Power Filter-APF (APF) to come to exist in compensation network and idle.The general principle of Active Power Filter-APF is, detect the voltage and current of target compensation, the command signal of offset current is calculated through instruction current computing circuit, this signal amplifies through offset current circuit for generating, draw offset current, the harmonic wave that will compensate in offset current and load current and the electric current such as idle are cancelled out each other, and finally obtain the source current expected.

The electric drive control system be commonly used at present in oil drilling machine platform is VFD system (frequency control driving control system), electrical network AC600V alternating current is first become direct current with diode rectification or thyristor rectifier by each borer system unit in this system, through large value capacitor filtering, reversals is completed again by IGBT three-phase bridge, obtain voltage and all adjustable alternating current of frequency, drive the winch on this unit, slush pump and top to drive or the electric machinery equipment such as rotating disk.

The scheme being usually used in solving input harmonics of electric power network and energy back problem in the market has two kinds, respectively as depicted in figs. 1 and 2.What Fig. 1 adopted is the compound circuit that uncontrollable rectification adds APF, and is configured with other energy ezpenditure braking circuit.The advantage of the program is that diode rectifier circuit is simple and reliable, and APF capacity is little.The four-quadrant full-controlled rectifier energy that Fig. 2 adopts can the circuit mode of feedback, although number of devices is less compared with last scheme, circuit is simple, but the former entirely to control module (APF) capacity be only about 40% of the latter's full-controlled rectifier module capacity, so the cost of the program is higher.

VFD system is in moderating process, and electric machinery load is in generating state, and the electricity sent feeds back to the electric capacity on DC bus after the parasitic diode full-wave rectification of IGBT pipe, makes the voltage rise at electric capacity two ends.In order to be discharged by electric charge unnecessary on capacitor, this just needs to access brake resistance, converts thermal energy consumption to fall by brake resistance.This will cause the loss of energy.

Generally harmonic wave is all produced by nonlinear load, therefore the most effective way preventing harmonic current injection drilling machine platform electrical network is installing filter near harmonic source, the harmonic wave flow through in filter is just in time offseted with the harmonic wave of harmonic source, thus can effectively stop in harmonic wave inflow system.For VFD system, in order to obtain good harmonic compensation effect, preferably near each VFD, APF unit is installed.This adds the complexity of system undoubtedly, is also unfavorable for Integration Design.

As can be seen from the above analysis, uncontrollable rectification as shown in Figure 1 adds APF scheme and needs separate configurations active power filtering unit and copped wave brake unit, during real work, and the equal time-sharing work of each unit.During braking, the input current of mains side is zero, and without the need to APF cell operation, APF is in idle state; During traction, brake unit is in idle state, now only needs APF to work.Therefore the program not only increases complexity and the cost of system, also reduces the utilance of equipment.Four-quadrant full-controlled rectifier scheme shown in Fig. 2 can realize the two-way flow of energy, therefore can realize rectification and energy back braking function, and without the need to joining APF filter.But because regenerative braking power is generally about 40% of traction power, make the utilance of equipment reduce, the cost of full-controlled rectifier scheme also adds a small amount of APF scheme higher than uncontrollable rectification, and uncontrollable rectifier is higher than full-controlled rectifier reliability.

Summary of the invention

In order to solve the shortcoming that above-mentioned two kinds of common scheme exist, the utility model is according to integrated design theory, by the function and service of active power filtering unit and energy ezpenditure brake unit to together with, filtering and energy feeding braking function is completed with active power filtering unit (APF), then rectification unit and active power filtering unit combination to together with, improve utilization rate of equipment and installations, reduce cost and the complexity of VFD system.

The utility model specifically adopts following technical scheme:

A kind of compound circuit being integrated with rectification, active power filtering and energy back function, it is characterized in that comprising rectification unit, active power filtering and reactive compensation unit and clamp circuit, rectification unit is directly connected at AC with active power filtering and reactive compensation unit, and connected in DC side by clamp circuit, clamp circuit is connected to active power filtering and between reactive compensation unit and DC bus, for energy back provides loop.

Rectification unit together with active power filtering unit combination, makes compensation loop shorten by the utility model, also forms common bus simultaneously and exports, thus the equipment on DC bus can be made mutually to exchange power, to improve capacity usage ratio.When the AC portion of electric network source output current never controlled rectifier flows to direct current component, containing a large amount of harmonic wave and idle in electric current, therefore need source filter and carry out filtering and reactive power compensation; When the load (such as winch) connect after direct current component is slowed down or is declined, energy back is had to arrive direct current component, DC bus-bar voltage is caused to raise, diode clamping circuit is connected between active power filtering unit and DC bus, for energy provides loop from deceleration loading through active power filtering unit feedback grid, thus stable DC voltage.This device can compensate preferably to the harmonic current in drilling platforms electrical network, when the load (as winch) connect after also solving direct current component declines the over-voltage protection that produces, feedback load braking energy is to electrical network, and energy-saving efficiency is high.

The utility model has following beneficial effect:

1, realize the integrated design of rectification, active power filtering, energy back braking, together with circuit integrated to APF circuit and energy back arriving, save energy-dissipating brake circuit and brake resistance thereof, reduce device fabrication cost;

2, rectification unit and active power filtering unit are fitted together and compensation loop are shortened, and are convenient to obtain good compensation effect, also form common bus simultaneously and export, thus can utilize the energy on bus fully;

3, the utility model circuit mutually can switch between active power filtering state and energy back state, time-sharing work, adapts with the time-sharing work of rectification operating mode and energy back operating mode, to improve utilization rate of equipment and installations;

4, contain a large amount of harmonic waves in uncontrollable rectification, after adding APF unit, the humorous reactive current that involves in electrical network input power is compensated preferably, reduce the loss of electrical network, decrease harmonic current;

5, comparatively IGBT controlled rectification reliability is higher for diode rectification, even if the APF device in the utility model damages, there is no filter function and energy back function, the direct current supply of follow-up load is not affected yet, also mechanical braking can be taked during braking to consume the energy of braking, thus do not affect traction and the braking of follow-up motor load.

Accompanying drawing explanation

Fig. 1 is that uncontrollable rectification adds APF compound schematic structure diagram.

Fig. 2 is four-quadrant rectification scheme structure chart.

Fig. 3 is the VFD system configuration schematic diagram comprising the utility model compound circuit.

Fig. 4 is conventional parallel connection type APF system block diagram.

Fig. 5 is the system architecture diagram of application the utility model circuit.

Fig. 6 is parallel connection type active electric filter equivalent electric circuit.

Fig. 7 a is APF working state structure figure.

Fig. 7 b is energy back working state structure figure.

Embodiment

Below in conjunction with specific embodiment, the utility model is further detailed.

Consider to there is a large amount of power electronic equipments in drilling platforms, and these equipment can produce a large amount of harmonic waves, so the quality of power supply in order to improve electrical network, Active Power Filter-APF must use.But there is a large amount of winch equipment in this electrical network, these equipment are in moderating process, and winch is in generating state simultaneously.The electricity sent, through and IGBT pipe reverse parallel connection fly-wheel diode full-wave rectification after feed back to DC circuit, make direct voltage increase, the equipment on DC bus can be damaged.For solving main these two subject matters existed in drilling machine platform electrical network, have employed a kind of active power filtering and energy back brake structure.

As shown in Figure 3, the utility model compound circuit comprises rectification unit M1, active power filtering and reactive compensation unit (APF unit) M2 and clamp circuit, rectification unit M1 is directly connected at AC with active power filtering and reactive compensation unit M2, and connected in DC side by clamp circuit, clamp circuit is connected to active power filtering and between reactive compensation unit M2 and DC bus, provides loop for energy transmits from winch load to active power filtering unit.

Rectification unit M2 adopts uncontrollable rectification circuit to realize.Clamp circuit adopts diode D to realize, and the positive pole of diode D connects direct current positive bus, and negative pole connects the direct current anode of active power filtering and reactive compensation unit M2, and the direct current negative terminal of active power filtering and reactive compensation unit M2 connects direct current negative busbar.Active power filtering and reactive compensation unit M2 adopt three-phase three-wire active filter circuit to realize, by being connected to the inductance of AC, inverter bridge that the IGBT of 6 anti-paralleled diodes forms and the high-voltage capacitance that is connected to DC bus two ends forms.

Fig. 4 is conventional parallel connection type APF system architecture diagram, and Fig. 5 is the system architecture diagram of application the utility model circuit.Contrast this two block diagram known, circuit of the present utility model comparatively common are the circuit of active power filter, adds clamp circuit.When U1 is greater than U2, diode D is reverse-biased, and busbar voltage does not affect APF side direct voltage, and now circuit working is in APF state; When U1 is less than U2, diode D conducting, the unnecessary energy of DC side is released by active power filtering and reactive compensation unit M2, thus reduces the impact to rectification circuit, and now the utility model circuit working is in energy back state.

For parallel connection type active electric filter, as shown in Figure 6, and the offset current that Voltage type converter produces meets equation below to its equivalent circuit diagram, namely

$L\frac{{\mathrm{di}}_c\left(t\right)}{\mathrm{dt}}+{\mathrm{Ri}}_c\left(t\right)=u_c\left(t\right)-u_s\left(t\right)$

I in formula _c(t), u _s(t) and u _ct () is respectively offset current, the output voltage of system voltage and active power filter inverter, and L, R are respectively equivalent inductance and resistance, and under normal circumstances, equivalent resistance is very little, therefore can ignore.Shown above formula can be approximately:

$L\frac{{\mathrm{di}}_c\left(t\right)}{\mathrm{dt}}{\≈u}_c\left(t\right)-u_s\left(t\right)$

Therefore, the size of the offset current of Active Power Filter-APF generation depends primarily on inverter output voltage u _cthe size of (t).And when the value of outputting inductance is certain, in order to strengthen the follow-up control of electric current, the output voltage of inverter can only be improved, and the size of this value is directly proportional to the voltage swing of direct current, therefore known electric capacity both end voltage is higher, active electric power filter to output current follow-up control is also stronger.Therefore make diode cathode voltage U 1 be a bit larger tham the peak value of rectifier input voltage.

The utility model compound circuit can be operated in two kinds of operating states:

APF state, now U1 ﹥ U2, circuit is mainly used to compensation harmonic electric current, and improve system power factor, its equivalent structure figure is as shown in Figure 7a;

Energy back state, now U2 >=U1, energy unnecessary on DC bus, by APF unit (working in inverter mode), feeds back to input power side, and use to other AC load on electrical network, this state equivalent structure figure as shown in Figure 7b.

Therefore, the utility model active power filtering and energy back braking circuit have very strong practicality.

Claims (4)

1. one kind is integrated with the compound circuit of rectification, active power filtering and energy back braking function, it is characterized in that comprising rectification unit (M1), active power filtering and reactive compensation unit (M2) and clamp circuit, rectification unit (M1) is directly connected at AC with active power filtering and reactive compensation unit (M2), and connected in DC side by clamp circuit, clamp circuit is connected to active power filtering and between reactive compensation unit (M2) and DC bus, for energy back provides loop.

2. be integrated with the compound circuit of rectification, active power filtering and energy back braking function as claimed in claim 1, it is characterized in that described rectification unit (M1) adopts uncontrollable rectification circuit to realize.

3. be integrated with the compound circuit of rectification, active power filtering and energy back braking function as claimed in claim 1, it is characterized in that clamp circuit adopts diode to realize, the positive pole of diode connects direct current positive bus, negative pole connects the direct current anode of active power filtering and reactive compensation unit (M2), and the direct current negative terminal of active power filtering and reactive compensation unit (M2) connects direct current negative busbar.

4. be integrated with the compound circuit of rectification, active power filtering and energy back braking function as claimed in claim 1, it is characterized in that active power filtering and reactive compensation unit (M2) adopt three-phase three-wire active filter circuit to realize.