DE10118504A1 - Method and device for predictive correction of control or manipulated value deviations in current or voltage regulators - Google Patents

Abstract

The method involves predictive adaptation of the reference parameters on which the current or voltage regulation is based by additional implementation of conditioning control elements depending on the transfer function of the regulating circuit or the system equations within the existing control schema for current or voltage regulation. AN Independent claim is also included for the following: an predictive correction of regulation or control errors for current or voltage regulators.

Description

The invention relates to a method and a device for predictive Kor correction of control or manipulated value deviations that occur when processing changes Current or voltage quantities, especially when processing upper vibrations, in corresponding current or voltage control elements, in particular observed when using proportional-integral or integral controllers are.

The increasing power requirements in both the private and industrial sectors as well as the development and use of increasingly powerful and powerful Machines and drive systems and the associated appearance always strength rer or larger power electronic and electrical loads, as well as by this Harmonics caused, especially in the energy supply area, but also in traffic engineering to a number of adverse side effects. So lead harmonics caused by nonlinear loads, for example, to a Impairment of the supply currents or voltages or their quality and hence the quality of service, what for consumers connected to the same electrical supply are connected to the occurrence of malfunctions and / or device failures or defects can mean.  

One way to deal with the problem is to use active Filters that are used here as a kind of regulated countercurrent source.

Accordingly, active filter elements connected in parallel can be found in many technical Areas for regulation and / or compensation by nonlinear loads called current harmonics and resulting reactive currents to ensure that the supply currents their sinusoidal when nonlinear loading begins maintain course and a power factor of one is maintained.

The main difficulty here is the simultaneous regulation of a ver equally large number of current harmonics. Their maximum controllable highest frequency component according to theoretical considerations and considerations is predetermined by half the switching frequency of the active filter elements used.

The processing of the load currents or the basic electricity and the associated electricity Harmonics are based on the principles of the SRF (Synchronous Reference Frame) or FSRF (Fundamental Synchronous Reference Frame) theory. According to In the FSRF theory, both the currents and, if appropriate, the Voltages in a three-phase static or stationary, non-rotating 123- Reference system with three corresponding to the individual phases and each 120 ° twisted against each other, intersecting in a common origin determined and into a static Cartesian reference system with an α, β and zero Transfer axis. A new one is made from the aforementioned static αβ reference system Transfer of the measured variables to the SRF or FSRF reference system. This is what it is about is a Cartesian reference system with a d, q and zero axis, its d and q-axis, in the FSRF reference system synchronous with the frequency of the fundamental, rotates around the zero axis of the reference system. The default direction of rotation is counter to the movement of a watch and thus corresponds to that Direction of rotation of the co-system of the fundamental vibration. In the FSRF reference system they are Currents or voltages separated by active and reactive components, with the d-axis Active and the q-axis the reactive component of the current or voltage values shown reproduces.  

Shines the vector formed from three phase-shifted currents or voltages in the room pointer representation of the three-phase static reference system with the Fre frequency of the fundamental current or voltage oscillation around the origin, so the alternating current or voltage quantities of the fundamental wave according to Trans formation in the dq reference system, which is synchronous with the frequency of the basic oscillation supply rotates, reproduced as direct current or voltage quantities and the ver my rotation stops.

This fact is used for control-related signal processing because due to the control elements used, direct current or voltage is more advantageous to control or process quantities as AC or voltage quantities. This can be attributed to the fact that when processing AC or -Voltage quantities using appropriate control elements, in particular from Pro Portional-integral controllers (PI controllers) and / or integral controllers (I controllers) in stationary During operation, a control or manipulated value deviation occurs, whereas during processing a control or manipulated value deviation is reached from zero.

If, for example, harmonics occur in the supply currents, then these are transformed together with the fundamental into the FSRF reference system, have changed frequency due to their relative frame of reference there, however, a different order than before. For example, the current top swing fifth order, which is typically a negative system super oscillation is acting, the space pointer against the direction of rotation of the basic oscillation rotation at five times the frequency, transformed into the FSRF reference system, see above their rotation frequency measured relative to the reference system changes and so does he appears as a sixth-order negative harmonic.

With existing asymmetries, each harmonic can have its own counter-, and have zero system components. The zero system components are those Designates frequency components that occur on the neutral conductor.

At this point it should be noted that in the FSRF reference system, compared to the dreipha static system, a negative sequence component of the fundamental wave as negative sequence harmonic  second order occurs and by regulating this upper load symmetry can be achieved in the FSRF system, so that no separate, additional control specifically for load balancing is required.

To generate the reference currents required for an active filter element first the load currents with current fundamental and current harmonics using a Clark transformation, represented by equation I, into the static αβ- Reference system transferred and from there by a given in equation II Transfer park transformation into the FSRF reference system.

Clark transformation:

where I ₁ , I ₂ and I ₃ denote the three load currents occurring in the static or stationary, non-rotating 123 reference system, corresponding to the three phases, and I _α , I _β and I ₀ denote the three load currents transformed into the αβ reference system .

Park transformation:

where I _α , I _β and I ₀ denote the three load currents transformed into the αβ reference system and I _d , I _q and I ₀ the three load currents transformed into the dq reference system (FSRF) and ρ the phase position of the vector pointer of the supply voltage in the static 123 reference system gives.

The aforementioned transformations can also be carried out in a single transformation perform step.

Since the active current shown on the d-axis of the FSRF reference system denies the contains useful DC current component of the fundamental oscillation of the load current extract this DC component by means of a low-pass filter and the ge Subtract the entire active current component of the d-axis, which means that only the one to be compensated current share of electricity is retained.

Since the counter currents required to compensate the harmonic components active filter elements of the same size, but with the opposite sign as the Load current must be measured in the reference current generation Current harmonics inverted and processed as reference values. In addition losses caused by the active filter system or passive / active Loads or supply units on the DC link from the supplying Mains are supplied. This is done via a DC voltage regulator, which the Refe current in the d-axis corrected.

A proportional integral controller (PI controller) is used for current control regulates the current to the respective reference value. To the control voltages or the To receive control signals for the converter or converter of the active filter the output signal of the PI current regulator, which shows the voltage drop at the on reproduces the active filter, plus the supply voltage additional decoupling components that crosstalk between the reactive and active prevent shares, deducted. The supply voltages become this equivalent to transferring the load currents into the FSRF reference system. The control chip The inverter or converter are then inverted using an inverse Park transformation according to equation III into the static αβ reference system and finally by means of an inverse Clark transformation according to equation IV into the three phase static or stationary, non-rotating 123 reference system.  

Inverse park transformation:

where U ^* _fd , U ^* _fq and U ^* _{f0 designate} the three reference _{voltages of} the converter or converter transformed into the αβ reference system and U ^* _fα , U ^* _fβ and U ^* _f0 and ρ shows the phase position of the vector pointer of the supply voltage in the static 123 reference system.

Inverse Clark transformation:

where U ^* _fα , U ^* _fβ and U ^* _{f0 denote} the three reference _{voltages of} the converter or converter transformed into the αβ reference system and U ^* _f1 , U ^* _f2 and U ^* _f3 the three reference voltages transformed into the three-phase static reference system.

Here, too, the aforementioned transformations can alternatively be carried out using a single one perform the transformation step.

The control and reference voltages U ^* _f1 , U ^* _f2 and U ^* _f3 generated and transformed into the three-phase static 123 reference system are converted by means of pulse width modulation into the switching signals required for the semiconductor valves of the current or converter of the active filter and the Semiconductor valves supplied.

If only a single proportional-integral controller is used in the FSRF reference system Regulation of the DC and AC components of each reference system axis, both  If the d and q axes are used, a control or control value deviation in both the phase and the amplitude, based on the AC components on the reference values. Both, both amplitude and Phase errors take place with increasing frequency and thus the order of processing harmonics.

The control is sensitive to sampling cycles, dead times, harmonics and Asymmetries in the supply voltage.

The pilot control of the supply voltage within the control is not very ge due to the sampling cycle and a dead time during processing the regulation is delayed. Such control behavior can, however, be used measurement data from the previous fundamental oscillation cycle correct.

The aforementioned facts are also to be considered in particular for the load currents pull and apply to them.

Since the voltage curves generated by the active filter derive the load current correspond, it is necessary to use the information from the previous one Fundamental oscillation cycle for the load current has a phase lead of two sampling cycles to provide. The phase reserve and the use of the information from the previous one cycle for both the supply voltage and the load current or be switched on or off, depending on whether and how large the difference between between the values of the previous fundamental cycle and the current is measured values. By applying or applying a phase lead to the Supply voltage and the load current can be the performance of the control increase comparatively significantly. By applying a phase lead to the Load current, the phase problem of the proportional integral controller is reduced wherever against amplification errors occurring for AC quantities remain unchanged.

In known methods, forward-looking current regulators are used, which we consist of a PI controller, whose integrator after each run Sampling cycle is reset. The proportional control tries a "dead beat" -  Achieve operating behavior, whereas the integral controller tries to be due To compensate for non-ideal behavior errors or deviations.

It is also possible to use the operating parameters of the PI controller used in this way to optimize that a maximum bandwidth and accordingly in terms of change minimized control deviation is achieved.

The transformation of harmonics into individual reference spaces on which Basis rotating Be synchronous with the frequency of the respective harmonic train systems (ISRF theory) and the corresponding conversion of a change into a DC or voltage size allows further processing without significant control or manipulated value deviations. However, this is a comparative one great effort required.

The invention is based on the object in the context of a current control Processing of alternating current quantities by means of appropriate control elements, as with for example proportional-integral and / or integral controller, occurring control or To minimize control value deviations.

This task is accomplished by a method and a predictive device Correction of when processing AC or voltage quantities, esp especially when processing harmonics, occurring control or Adjustment value deviations in current or voltage control elements by adjusting the Reference quantities of those based on proportional-integral and / or integral controllers Current or voltage regulation using the transfer function of the Control loop or the system equations solved.

The system equations of an active filter system can be specified as follows after transformation into the rotating FSRF reference system:

where U _f the voltages of the active filter, I _f the current of the active filter, dl _f the change in the current of the active filter, dt the time interval of the current change dl _f in the dq reference system, in each case according to the active (d index) and reactive component (q index) separately, L _f denote the input inductance of the active filter, R _f the ohmic resistance of the active filter and ω the fundamental frequency of the supply voltage.

If, when using an active filter with converter and choke coil, the time constant of the PI controller of the current control used is adjusted to the time constant of the choke coil of the active filter, the following transfer function results for the closed feedback loop in the frequency domain:

where I _f the current of the active filter, I ^* _f the reference current of the active filter, K _i the gain of the FSRF current regulator, T _i the time constant of the FSRF current regulator, s the Laplace operator, L _f the input inductance of the choke coil of the active filter and ω denote the fundamental frequency of the supply voltage.

It can be seen from equation VI that no rule is involved in direct current quantities softening occur and that with AC quantities with increasing frequency or order of the harmonic a percentage increase in both the phase and also the amplitude error occurs.

However, the regulating or control value deviations occurring can be minimized by _f from the reference current I ^*, as follows, the foresight corrected reference current I ^* _f ^PRED,

is formed, K _i denoting the gain of the FSRF current regulator, T _i the time constant of the FSRF current regulator, L _f the input inductance of the active filter and s the lapla ceoperator.

The differential part of equation VII can be approximately written as

and I ^* _f the reference current of the active filter, K _i the gain of the FSRF current controller, T _i the time constant of the FSRF current controller, s the Laplace operator, L _f the input inductance of the active filter, K _pred the gain of the predictive control and ω denote the fundamental frequency of the supply voltage.

Accordingly, the differential component of equation VII, according to equation VIII, can be approximated to the transfer function of a first-order low-pass filter, and thus the noise amplification can be reduced. The sampling time of the current controller determines the upper limit of the gain K _{pred of} the predictive control.

Comparatively better results are achieved if the predictive re at five times the normal control speed.

An alternative way of representing the differential component set out in equation VII is to process the system equations using the reference values that result when using an active filter for current harmonic compensation as follows:

or transformed to

where I ^* _f the reference current of the active filter, U the supply voltage, U ^* _f the reference voltage of the active filter, each separated by active (d-index) and reactive component (q-index), s the Laplace operator, L _f the input inductance of the Inductor of the active filter, R _f denote the ohmic input resistance of the active filter and ω the fundamental frequency of the supply voltage.

When using the reference voltage at the output of the current controller with active component U ^* _Lfd and _{reactive component} U ^* _Lfq , the following relation can be derived from equation X:

For all practical fields of application, the ohmic losses can either be neglected or integrated into the decoupling components, so that the ohmic components can be eliminated from the aforementioned equations. The predictive de to be determined differential component according to equations VII and VIII results accordingly

where I ^* _f the reference current of the active filter, U ^* _Lf the reference voltage at the output of the current controller, each separated by active (d-index) and reactive component (q-index), s the Laplace operator, K _i the gain of the current control and L _f denote the input inductance of the active filter.

A minimization or compensation of those occurring within the framework of the current regulation Control or manipulated value deviations are accordingly due to a predictive correction rectification or regulation based on the power transmission function.

The implementation of the predictive correction or regulation in the existing de Current control can be done in different ways, with forward-looking correction and regulation of control or manipulated value deviations, the processing of AC or voltage quantities in current or Voltage regulators, especially when using proportional-integral or inte Grail controllers occur a predictive adaptation of the current or voltage regulation underlying reference values by additional Im implementation of depending on the transfer function of the control loop or System equations conditioned rule elements into the existing rule scheme Current or voltage regulation is achieved and thereby one in advance Compensation or regulation of the processing of AC or -voltage values, especially when processing harmonics, possible control or manipulated value deviation is taken into account.

The method according to the invention opens up a wide range of applications in for example in connection with active line-side converters (active front-end converter) or power converters to correct the power factor in rail and ind flow area. In high-performance converters, for example, the converted voltage does not show that same harmonics as the supply voltage, suggesting that the converter itself causes some current harmonics. these can corrected in a simple manner by means of the method according to the invention and be compensated. Also the reduction of selected individual harmonics on the DC voltage side of the line-side converter (active front-end conver ter) is possible using the procedure. For example, the harmonic is fourth Order on the DC side of traction converters is greatly exaggerated and can with by means of the aforementioned method, the same also applies to STATCOM's (Static Compensators).

This also applies to the area of uninterruptible power supplies (UPS) according to application procedures. Here, in contrast to active filters, the sinusoidal one applies  Get output voltage and quality of output voltage too improve. By improving the voltage quality, the UPS Output current to the load current possible, which in turn means that the upper vibrations are prevented from this on the output side connected parallel load the capacitor. As a result, the function of the output-side capacitor Filters are reduced to that of a switching frequency filter, whereby its size mi can be minimized. The reduction in the size of the capacitor filter leads simultaneously to improve the dynamic properties of the UPS voltage control. In this way the cause of the disturbance, for example a non-linear one, can be identified Eliminate load current directly at the source of the problem, namely current regulation.

Drive controls are also affected by the occurrence of harmonics in the Current path disturbed. Relevant sources of such harmonics can be poor mechanical structure as well as a strongly disturbed DC voltage when switched on be food. Harmonics, even with comparatively small amplitudes, can cause torque oscillations that can be large enough Damage the engine and other mechanical parts and components sustainably. As a rule, this damage leads to delays due to repairs and downtimes as well as immense costs. The Pro solution is also here blems in the compensation of harmonics occurring by the erfindungsge procedure.

The implementation or implementation of the method according to the invention can be done in hard-wired form using analog components and control elements as well using digital processors or in the form of data processing programs using digital control elements, suitable interfaces for Data or signal input and output and a correspondingly designed data processing device or as a combination of the aforementioned possibilities and construction elements done.

The further explanation and presentation of the invention is based on a few characters tion and examples.  

Further advantageous embodiments of the invention are the figure descriptions and the dependent claims.

Show it:

Fig. 1: Schematic diagram of a system arrangement with an active filter connected in parallel;

Fig. 2: structural diagram of a three-phase active filter;

Fig. 3: three reference systems: a static three-phase reference system, a static Cartesian reference system and a rotating Cartesian reference system;

Fig. 4: Scheme of a reference current generation based on the FSRF theory;

FIG. 5 shows the Bode diagram of the power transfer function in FSRF reference system with a closed control loop;

Fig. 6: Control scheme of an FSRF current control;

Fig. 7: Control scheme to be integrated in the FSRF current control for anticipatory adaptation of the reference current on the basis of the current transfer function of the control;

Fig. 8: In the FSRF current control to be integrated control scheme for predictive adjustment of the reference voltage on the basis of the system equations;

Fig. 9: Modified control scheme to be integrated into the FSRF current control for predictive adaptation of the reference voltage on the basis of the system equations;

Fig. 10: Modified control scheme to be integrated into the FSRF current control for predictive adaptation of the reference voltage based on the system equations;

Fig. 11: Measured non-linear load current;

Fig. 12: Supply current disturbed by harmonics;

Fig. 13: By means of the present invention predictive scheme si nusförmiger adjusted supply current.

The work or mode of action and structure of a control procedure with corrective In the following, regulation becomes compensation on the basis of regulation with an active filter tion of current harmonics caused by nonlinear loads.

In Fig. 1, a circuit configuration is shown in which a non-linear load is fed from a three-phase AC voltage source 11 12. An active filter 10 for compensating harmonics caused by nonlinear loads is connected in parallel with the load. An exemplary course of the supply voltage, the load current, the filter current or current of the active filter and the compensated supply current is shown in each case.

The exemplary construction of an active three-phase filter 10 with a converter 20 , with semiconductor valves 21 , inductors L _f , ohmic resistors R _f and capacitors 22 is shown in FIG. 2. The voltage across the capacitors 22 is regulated to maintain a constant virtual DC voltage U _dc . The network-side voltages U ₁ , U ₂ and U ₃ are determined and corresponding switching signals are generated, so that the voltage difference between U ₁ and U _f1 , U ₂ and U _f2 and between U ₃ and U _f3 assumes the desired value. By regulating the voltages U _f1 , U _f2 and U _f3 on the converter 20 , the filter currents I _f1 , I _f2 and I _{f3 can be} regulated and the active filter 10 can accordingly be operated as a type of regulated current source. The semiconductor valves 21 used are, for example, IGBTs (Insulated Gate Bipolar Transistors).

In Fig. 3 the different reference systems are presented, which are used in the control process for processing the fundamental and harmonics. In Fig. 3 on the left side, the three-phase static or stationary, non-rotating reference system or 123 reference system 30 is shown, the 1-, 2- and 3-axis offset by 120 ° in each case the three phases of the current or Voltage. Centrally in Fig. 3, the static or stationary, non-rotating Cartesian αβ reference system 31 is provided with α-, β- and illustrated zero axis, the currents or voltages men by means of a Clark-transformation from the three-phase Strö the aforementioned static reference system 30 result. A rotating Cartesian reference system 32 is shown on the right-hand side of FIG. 3, the rotating d-axis representing the active and q-axis the reactive component of the voltage or the current. The transfer or transition from the αβ reference system 31 to the dq system 32 takes place by means of a park transformation. If you want to go through the different reference systems in the opposite direction, the inverse transformations must be applied to the respective measured variables.

In Fig. 4, the reference current generation from the non-linear load currents is shown schematically based on the FSRF theory. To generate the reference currents for current control using an active filter element 10 (see FIG. 1), the load currents with current fundamental and current harmonics are first converted into a first step using a transformation element 40 using a Clark transformation, which is represented by equation I. stationary αβ reference system 31 (cf. FIG. 3) and from there in a second step by means of a further transformation element 41 , by means of the park transformation represented in equation II, into the FSRF reference system 32 (cf. FIG. 3) transfer. Since the DC active component represented on the d-axis of the FSRF reference system 32 contains the useful basic oscillation active component of the load current, this can be extracted in a third step by means of a low-pass filter 42 and subtracted from the total active current component of the d-axis at an addition point 43 , thereby only the current component _d to be compensated remains. Since the currents generated to compensate for the harmonics of the active filter element 10 (cf. FIG. 1) must be of an appropriate size, but with the opposite sign as the load current, the currents I _d , I _q and I _{0 determined are} in a fourth step inverted in a control element for reference current formation 44 and losses occurring in the d-axis caused by the active filter 10 (cf. FIG. 1) or other active components in the DC voltage intermediate circuit are compensated again by means of a DC voltage regulator 45 and thus the reference currents I ^* _fd , I ^* _fq and I ^* _f0 . In the DC voltage regulator 45 , the input signal of a proportional-integral regulator 47 is formed by forming the difference from the actual DC value and setpoint U ^* _dc at an addition point 46 . The output signal I _{dloss of} the PI controller 47 is fed to the control element for reference _{current formation} 44 .

The Bode diagram shown in FIG. 5 essentially reproduces the transfer function of the closed control or feedback circuit of the current control in the FSRF reference system, which can be represented in the following manner according to equation VI:

where I _f current of the active filter 10 (see FIG. FIG. 2), I ^* _f the reference current of the active filter 10 (see FIG. FIG. 2), K _{i is} the gain of the FSRF flow regulator, s rator the Laplaceope, L _f denote the input inductance of the active filter and ω the fundamental frequency of the supply voltage.

It is clear here, cf. Fig. 5, to see that DC variables a control or manipulated value deviation of zero, but with AC quantities, however, with increasing frequency or order of the harmonic a percentage increase in the control deviation, both in phase 50 and in amplitude 51 is recorded. Both the amplitude deviation and the phase deviation can be found in the diagram shown here as a function of frequency.

At this point it should be noted once again that the frequency and thus also the order of the highest controllable harmonic is predetermined by half the switching frequency of the converter 20 .

The systematic structure of a current control in the FSRF reference system is illustrated in FIG. 6. The reference _currents I ^* _fd , I ^* _fq and I ^* _f0 generated according to FIG. 4 are in a first step by means of a current regulator 60 with addition points 61 with the currents I _fd , I transformed into the FSRF reference system 32 (see FIG. 3) _fq and I _{f0 of} the active filter 10 (cf. FIG. 2) are compared and a proportional voltage control voltage U ^* _Lfd , U ^* _Lfq and U ^* _Lf0 corresponding to the respective current difference is generated by means of proportional-integral controller 62 . These in turn, each axis (see FIG. 4) for itself, at add-ons 63 with the respective supply voltages plus additional respective decoupling components, (+ ωL _f I ^* _fq ) for the d- and (-ωL _f I ^* _fd ) for the q axis. Then, in a second step, the resulting voltages U ^* _fd , U ^* _fq and U ^* _{f0 are converted} into a first transformation _element 64 by means of an inverse parking transformation and subsequently in a third step in a further transformation _element 65 by means of an inverse Clark transformation static three-phase 123 reference system 30 (cf. FIG. 4) and transferred to a pulse width modulator 66 . By means of the control voltages U ^* _f1 , U ^* _f2 and U ^* _{f3 to be supplied} , the latter generates the switching signals necessary for switching the converter 20 or the semiconductor valves 21 of the active filter 10 .

In Fig. 7, an implementation is for the present invention predictive control of the reference current I ^* _f of the active filter 10 (see FIG. FIG. 2) of a conventional order to compensate for the processing of AC quantities, and thus current harmonics on kicking regulating or control value deviations FSRF-based Current control shown. The predictive adaptation of the reference current is implemented here by means of a control element 70 , the transfer function of which is given by the right-hand side of equation VIII. Linking the original reference current I ^* _f with the correction value provided by the control element 70 at the addition point 71 results in the predictive reference current I ^* _f ^pred required for control or manipulated value compensation, which occurs for regulation and compensation of the current harmonics fed to a conventional FSRF current regulation becomes.

In Fig. 8, two alternative circuit arrangements for implementing the method to the invention OF INVENTION are based on the _f ^* set out in equation VII look ahead the reference current I ^PRED shown. In the upper diagram, a correction value equation is by means of an tragungsgliedes 80 whose transfer function is determined by the differential component of sliding chung VII determined, _f from the reference current I ^* is determined and _f linked via an addition point 81 to the reference current I ^*, which, according VII , the predictive reference ^current I ^* _f ^{PRED is} formed. After subtraction of the current of the active filter I _f from the forward-looking reference current I ^* _f ^PRED at a further addition point 61 , a forward-looking voltage ^value U ^* _Lf ^{PRED is} generated by means of a proportional-integral current controller 62 in the FSRF reference system provided for further processing at the output of the current control.

In contrast, the lower control diagram in FIG. 8 shows a somewhat different structure.

By combining the transmission element 80 with the proportional-integral controller 62 , a new control element 85 is formed, which determines a corrective voltage value from the reference current I ^* _f and adds this via a further addition point 84 to the reference voltage U ^* _Lf at the output of the current control 62 , a look-ahead reference ^voltage U ^* _Lf ^{PRED is} formed and made available for further processing. The reference voltage U ^* _Lf is formed by subtracting the current of the active filter I _f from the reference current I ^* _f at the addition point 61 and then processing the resulting current difference by means of the proportional-integral current regulator 62 in the FSRF reference system. The corrected or regulated voltage values U ^* _Lf ^{PRED compensate} for the control or manipulated ^{value deviations} that occur due to the processing of AC ^quantities .

Taking into account equation XII, the control structures shown in FIG. 8 can be further simplified and ultimately lead to the contents shown in FIG. 9.

In Fig. 9 of the active filter I after subtraction of the current _f from the reference current I ^* is a current difference _f at the summation point 61 by means of a proportional integral current regulator 62 in the FSRF- reference system corresponding reference voltage U ^* _Lf formed. The reference voltage U ^* _Lf is passed through a PI controller 92 with unity gain, and the resulting voltage value of the original reference voltage U ^* _Lf added at a second addition point 93rd The ^look-ahead reference ^voltage U ^* _Lf ^PRED arises from the addition.

In Fig. 10 a further control integration option and simplified implementation of the method according to the invention in an existing current control is shown ge. Equivalent to FIG. 9, the reference voltage U ^* _{Lf is also} determined here and a further PI control element 100 with the following transfer function

leads. Here, too, the result is a forward-looking reference voltage value U ^* _Lf ^PRED for correction and compensation by processing alternating current variables of control or manipulated value deviations that occur.

In Fig. 11, a phase is shown a non-linear afflicted with harmonics ge measured load current as a function of time.

The supply current of the non-linear load current, which is not optimally adjusted, is shown in FIG. 12 as a function of time. Remaining harmonic components that have not been fully compensated can be clearly seen in the current curve shown here.

In contrast, FIG. 13 shows a much smoother, sinusoidal current profile of the supply current, from which all non-linearities have been removed almost completely by means of the method according to the invention. It should be noted that a closed control loop was used here.

Reference symbol list

U ^* _dc

dc reference voltage or voltage setpoint
U _dc

dc actual voltage value
I _dc

dc-side current of the active filter

10th

K _udc

Amplification of the PI controller for dc voltage regulation
T _udc

Integration constant of the dc voltage PI controller
U ₁

, U ₂

, U ₃

Supply voltages in the three-phase static 123 reference system

30th

U generalized designation of the supply voltage
U _α

, U _β

Supply voltages in the stationary αβ reference system

31

U ₀

Zero-axis portion of the supply voltage
U _d

, U _q

Supply voltages in the rotating dq reference system (FSRF)

32

I ₁

, I ₂

, I ₃

Load currents in the three-phase static 123 reference system

30th

I generalized description of the load current
I _α

, I _β

Load currents in the static αβ reference system

31

I ₀

Zero-axis portion of the load current
I _d

, I _q

Load currents in the rotating dq reference system (FSRF)

32

T _p

Low pass filter time constant
_d

ac component of the d-axis (active component) load current
I _dloss

d-axes (active component) dc leakage current of the active filter system
I _f1

, I _f2

, I _f3

Active filter currents

10th

in the three-phase static 123- Frame of reference

30th

I _f

generalized description of the current of the active filter

10th

I _fα

, I _fβ

Active filter currents

10th

in the static αβ reference space

31

I _f0

Zero-axis component of the current of the active filter

10th

I _fd

, I _fq

Active filter currents

10th

in the rotating dq reference system (FSRF)

32

I ^* _fd

, I ^* _fq

Active component (d-axis) and reactive component (q-axis) of the reference current in the FSRF reference system

32

I ^* _f0

Zero-axis component of the reference current in the FSRF reference system

32

I ^* _f

Generalized designation of the reference current in the FSRF reference system
I ^* _f ^PRED

Generalized designation of the reference current with foresight in the FSRF reference system
K _i

Amplification of the FSRF current controller or the FSRF current control
T _i

Time constant of the FSRF current controller or the FSRF current control
K _pred

Strengthening the forward-looking regulation for approximate differential renting
U ^* _Current

, U ^* _Lfq

Active component (d-axis) and reactive component (q-axis) of the reference voltage on Output of the current control in the FSRF reference room

32

U ^* _Lf0

Zero-axis component of the reference voltage in the FSRF reference space

32

U ^* _Lf ^PRED

Predictive reference voltage at the output of the current control in FSRF reference system

32

U ^* _fd

, U ^* _fq

Active component (d-axis) and reactive component (q-axis) of the resulting ref limit voltage of the active filter

10th

in the FSRF reference system

32

U ^* _f0

Zero-axis component of the reference voltage of the active filter

10th

in the FSRF Frame of reference

32

U ^* _fα

, U ^* _fβ

Resulting reference voltage of the active filter

10th

in the static αβ- Frame of reference

31

U ^* _f1

, U ^* _f2

, U ^* _f3

Resulting reference voltages of the active filter

10th

in three phases against the static 123 reference system

30th

U _f1

, U _f2

, U _f3

Active filter voltages

10th

in the three-phase static 123- Frame of reference

30th

ω fundamental frequency of the supply voltage
ρ position in the three-phase static 123 reference system

30th

L _f

, R _f

Input inductance (choke) and ohmic resistance of the active Filters

10th

C _dc

dc-side capacitor of the active filter

10th

s Laplace operator
J √-1

SRF (Synchronous Reference Frame); synchronously rotating reference system
FSRF (Fundamental Synchronous Reference Frame); Reference system rotating synchronously with the frequency of the fundamental oscillation

32

10th

active filter (power unit)

11

three-phase supply voltage

12

Load source

20th

Inverter or converter of the active filter

10th

21st

Semiconductor valves of the converter

21st

22

Capacitors of the DC voltage intermediate circuit

30th

three-phase static or stationary, non-rotating reference system or 123 reference system

31

static or stationary, non-rotating Cartesian αβ reference system

32

dq reference system (FSRF) rotating synchronously with the frequency ω

40

Clark transformation into the αβ reference system in

Fig.

4th

41

Park transformation into the dq reference system (FSRF) in

Fig.

4th

42

Low pass filter in

Fig.

4th

43

Addition point for eliminating the DC active components in

Fig.

4th

44

Control element for reference current formation in

Fig.

4th

45

DC voltage regulator in

Fig.

4th

46

Addition point for calculating the control deviation between the U _dc

- Actual and reference value

47

PI regulator of the DC voltage regulator in

Fig.

4th

50

Phase in

Fig.

5

51

Amplitude in

Fig.

5

60

Current controller of the FSRF control in

Fig.

6

61

Addition point of the current regulator for subtracting the current of the active filter I _f

from the reference current of the active filter I ^* _f

in

Fig.

6

62

PI controller of a conventional FSRF current control with the transfer function

63 further addition point of the current regulator for forming the voltage difference in FIG. 6
64 inverse park transformation into the αβ reference system in FIG. 6
65 inverse Clark transformation into the three-phase stationary reference system in FIG. 6
66 pulse width modulator
70 control or transmission element with the transfer function

in Fig. 7 71 addition point for the formation of I ^* _f ^PRED
80 control or transmission element with the transfer function

in FIG. 8 81 first addition point for the formation of I ^* _f ^PRED in FIG. 8 above
84 addition point or voltage addition point for the formation of U ^* _Lf ^PRED in Fig. 8 below
85 control or transmission element with the transfer function

in Fig. 8 below 92 control or transfer element with the transfer function

in FIG. 9 93 addition point or voltage addition point for forming U ^* _Lf ^PRED in FIG. 9
100 control or transfer element with the transfer function

in Fig. 10

Claims (17)

1. Procedure for the forward-looking correction and regulation of rule or Control value deviations that occur when processing alternating current or voltage sizes in current or voltage regulators, especially when using Propor tional-integral or integral controllers occur, a predictive (predicti ve) Adjustment of the reference on which the current or voltage regulation is based sizes by additional implementation depending on the transmission funct on the control loop or system equations conditioned control elements in the existing control scheme of current or voltage regulation takes place and thereby Compensation or regulation of the processing of AC or voltage quantities, especially when processing Harmonics, occurring possible control or manipulated value deviation is viewed. 2. The method according to claim 1, characterized in that when used to compensate for current harmonics when the active filter ( 10 ) is used, the reference current I ^* _{f of} the active filter is adjusted or regulated in advance. 3. The method according to claim 1, characterized in that when used to compensate for current harmonics when an active filter ( 10 ) with choke or input choke is used, the reference voltage U ^* _Lf across the inductance L _{f of} the active filter ( 10 ) is adapted or regulated in advance becomes. 4. The method according to any one of claims 1 to 3, characterized in that when used for the compensation of current harmonics when the active filter ( 10 ) is used, the transfer function of the closed current control loop is as follows:
and I _f the current of the active filter, I ^* _f the reference current of the active filter, K _i the gain of the current regulator, T _i the time constant of the current regulator, s the lapla ceoperator, L _f the input inductance of the active filter ( 10 ) and ω the Designate the basic oscillation frequency of the supply voltage. 5. The method according to any one of claims 1 to 4, characterized in that when used to compensate for current harmonics when used Akti vem filter with a given transfer function, a minimization of the control or manipulated value deviations of the current control by predictive adjustment of the reference current I ^* _{f of} the active Filters ( 10 ) according to
is reached, and K _i the gain of the current controller or the current control, L _f the input ^{inductance of} the active filter, I ^* _f ^PRED the anticipated reference current and s the Laplace operator. 6. The method according to any one of claims 1 to 5, characterized in that when used to compensate for current harmonics when the active filter ( 10 ) is used, the system equations describing the system, taking into account reference variables, are as follows:
and I ^* _f the reference current of the active filter, U the supply voltage, U ^* _f the reference voltage of the active filter, each separated by active (d-index) and reactive component (q-index), s the Laplace operator, L _f the input inductance of the active Filters, R _f denote the ohmic input resistance of the active filter ( 10 ) and ω the fundamental frequency of the supply voltage. 7. The method according to any one of claims 1, 2 or 4 to 6, characterized in that when used to compensate for current harmonics when the active filter ( 10 ) is inserted, the predictive adjustment of the reference current by means of a control element ( 70 ) with the following transfer function F he follows:
and I ^* _f the reference current of the active filter, K _i the gain of the FSRF current controller, T _i the time constant of the FSRF current controller, s the Laplace operator, L _f the input inductance of the active filter, K _pred the gain of the predictive control and ω denote the fundamental frequency of the supply voltage. 8. The method according to any one of claims 1, 2 or 4 to 6, characterized in that when used to compensate for current harmonics active filter ( 10 ), the predictive adjustment of the reference current I ^* _f by means of a control or transmission element ( 80 ) with the following transfer function F:
and K _i denote the gain of the current regulator or the current regulator, L _f the input inductance of the active filter and s the Laplace operator. 9. The method according to any one of claims 1, 3 or 4 to 6, characterized in that when used to compensate for current harmonics when the active filter ( 10 ) is used, the predictive adjustment of the reference voltage U ^* _Lf by means of a control element ( 85 ) with the transfer function
with the Laplace operator s, the input inductance L _{f of} the active filter and the time constant of the current control T _i , a correcting voltage value being determined from the reference current I ^* _f and the input _choke of the active filter ( 84 ) being added to the reference voltage U ^* _Lf 10 ) added and a predictive reference ^voltage U ^* _Lf ^{PRED is} formed, the reference voltage of the input choke U ^* _Lf from a comparison ( 61 ) between the reference current I ^* _f and the current of the active filter I _f and the subsequent processing of the resulting current differences obtained by means of a proportional-integral current controller ( 62 ). 10. The method according to any one of claims 1, 3 or 4 to 6, characterized in that when used for the compensation of current harmonics with an active filter ( 10 ), the predictive adjustment of the reference voltage U ^* _Lf after comparison ( 61 ) of the reference current I ^* _f with the current of the active filter I _f by means of a proportional-integral current regulator ( 62 ) a reference voltage U ^* _Lf corresponding to the current difference is formed, this is conducted via a PI regulator with gain one ( 92 ) and the resulting voltage value of the original reference voltage U ^* _Lf at an addition point (93) added, and thus the predictive reference voltage U ^{* PRED} _Lf is formed. 11. The method according to any one of claims 1, 3 or 4 to 6, characterized in that when used to compensate for current harmonics with an active filter ( 10 ), the predictive adjustment of the reference voltage U ^* _Lf after comparison ( 61 ) of the reference current I ^* _f with the current of the active filter I _f by means of a proportional-integral current regulator ( 62 ) a reference voltage U ^* _Lf corresponding to the current difference is formed and a further PI control element ( 100 ) with the transfer function
with the Laplace function s and the time constant of the current control T _i , and thus the predictive reference ^voltage value U ^* _Lf ^{PRED is} formed. 12. Device for predictive correction and regulation of control or manipulated value deviations that occur when processing AC or voltage quantities in current or voltage regulators, in particular when using proportional-integral or integral controllers, with an FSRF-based Current controller ( 60 ) with first addition points ( 61 ), proportional-integral controllers ( 62 ) and second addition points ( 63 ) both for the d-, q- and optionally 0-axis component in the FSRF reference system for generating control voltages (U ^* _Lfd , U ^* _Lfq and U ^* _Lf0 ) on the basis of current reference values or reference currents (I ^* _fd , I ^* _fq and I ^* _f0 ) and current _{actual values} , with the additional implementation of further control elements in the current controller ( 60 ) a predictive adaptation or control or correction of the reference _currents (I ^* _fd , I ^* _fq and I ^* _f0 ) and consequently the stray voltages (U ^* _Lfd , U ^* _Lfq and U ^* _Lf0 ) or the stray voltages (U ^* _Lfd , U ^* _Lfq and U ^* _Lf0 ) is reached directly. 13. The apparatus according to claim 12, characterized in that for the forward-looking adjustment or control of the reference current when using an active filter ( 10 ) both for the d-, q- and possibly 0-axis portion in the FSRF reference system at least one additional control element ( 70 ) with the transfer function F
is implemented on the input side in the current controller ( 60 ) and the additional control element ( 70 ) is connected electrically in parallel in the current path of the reference current upstream of the respective first addition point ( 61 ) and the output signal of the control element ( 70 ) is also connected via a further addition point ( 71 ) the reference current (I ^* _f ) is linked to form a predictively corrected or regulated reference ^current I ^* _f ^PRED , where K _{i is} the gain of the FSRF current regulator, T _{i is} the time constant of the FSRF current regulator, s is the Laplace operator, L _{f is} the input inductance of the active filter, K _{pred denote} the gain of the predictive control and ω the fundamental frequency of the supply voltage. 14. The apparatus according to claim 12, characterized in that for the forward-looking adjustment or control of the reference current when using an active filter ( 10 ) for both the d-, q- and possibly 0-axis portion in the FSRF reference system at least one additional control element ( 80 ) with the transfer function F
is implemented on the input side in the current controller ( 60 ) and the additional control element ( 80 ) before the respective first addition point ( 61 ) is electrically connected in parallel in the current path of the reference current I ^* _f and the output signal of the control element ( 80 ) is in each case via a further addition point ( 81 ) is linked to the reference current I ^* _f to form a forward-looking corrected or regulated reference current and K _{i designate} the gain of the current regulator or current regulator, L _f the input inductance of the active filter and s the Laplace operator. 15. The apparatus according to claim 12, characterized in that for the forward-looking adjustment or control of the control voltage U ^* _Lf using egg nes active filter ( 10 ) both for the d-, q- and optionally 0-axis portion in the FSRF reference system at least each an additional control element ( 85 ) with the transfer function F
implemented with the Laplace operator s, the input inductance L _{f of} the active filter and the time constant of the current control T _i in the current controller ( 60 ) and the respective first addition point ( 61 ) and the respective PI control element ( 62 ) are electrically connected in parallel, the additional control element ( 85 ) on the input side the reference current I ^* _{f is} fed in and the output side voltage signal is linked via a further re addition point ( 84 ) to the control voltage U ^* _Lf and thereby a predictively corrected control voltage U ^* _Lf ^{PRED is} formed , which is fed to the second addition point ( 63 ) of the current regulator. 16. The apparatus according to claim 12, characterized in that for the forward-looking adjustment or control of the control voltage U ^* _Lf when using egg nes active filter ( 10 ) both for the d-, q- and optionally 0-axis portion in the FSRF reference system at least one additional PI control element ( 92 ) with amplification one and the transfer function F
with the Laplace function s and the time constant of the current control T _i , implemented in the current controller ( 60 ) and electrically connected to the respective PI control element ( 62 ), the control voltage U ^* _{Lf being} fed into the additional control element ( 85 ) on the input side and the voltage signal on the output side is linked to the control voltage U ^* _Lf via a further add-on point ( 93 ), and as a result a predictively corrected control voltage U ^* _Lf ^{PRED is} formed, which is fed to the second addition point ( 63 ) of the current regulator. 17. The apparatus according to claim 12, characterized in that for the forward-looking adjustment or control of the control voltage U ^* _Lf when using egg nes active filter ( 10 ) both for the d-, q- and optionally 0-axis portion in the FSRF reference system at least one additional control element ( 100 ) each with the transfer function F
with the Laplace function s and the time constant of the current control T _i , implemented in the current controller ( 60 ) and the PI control element ( 62 ) electrically connected in series, the additional control element ( 100 ) being fed with the control voltage U ^* _{Lf on the} input side and the output-side, anticipatory corrected control voltage U ^* _Lf ^{PRED is fed to} the second addition point ( 63 ) of the current regulator.