CA2300306A1 - Method and device for improving the current quality of an overlay network - Google Patents
Method and device for improving the current quality of an overlay network Download PDFInfo
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- CA2300306A1 CA2300306A1 CA002300306A CA2300306A CA2300306A1 CA 2300306 A1 CA2300306 A1 CA 2300306A1 CA 002300306 A CA002300306 A CA 002300306A CA 2300306 A CA2300306 A CA 2300306A CA 2300306 A1 CA2300306 A1 CA 2300306A1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
- H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
- H02J3/1842—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/20—Active power filtering [APF]
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Abstract
The invention relates to a method and device for improving the current quality of a superimposed network (14) by means of a compensation device (2) which is connected parallel to the network (14) and to a load (12) and provided with a pulse current converter (4). The control and regulating system (10) of the converter determines a transmittance space vector (ü) on the basis of a supply voltage and line current space vector (uN,iN) together with the actual value of a direct current voltage(Vdc). According to the invention, a compensated voltage fundamental space vector (uk,1) comprising a space vector for a compensated voltage fundamental positive phase sequence system and a space vector for a compensated voltage fundamental negative phase sequence system is generated. This enables the compensation device (2) to balance a high dynamic load and to compensate reactive power in relation to the fundamental frequency currents of a particular load (12), so that said load (12) when seen from the point of view of the superimposed network in relation to the fundamental mode can appear as a three-phase, symmetrical, ohmic resistance.
Description
w CA 02300306 2000-02-09 , [67190/973556]
METHOD AND DEVICE FOR IMPROVING THE CURRENT QUALITY OF AN
cJVERLAY NETWORK
Specification The invention relai=es to a method and a device for improving the current quality of an overlay network using a compensation device coupled parallel to the network, said compensation device having a pu:Lse-controlled converter having at least one capacitive memory, a matching filter and an automatic control device, a transmission ratio space vector being determined dependent on a determined line voltage space vector and line current space vector and on an intermediate circuit voltage, control signals for the pulse-controlled converter being generated from the transmission ratio space vector.
From the publication "Shunt-Connected Power Conditioner for Improvement of Power Qua:Lity in Distribution Networks,"
printed in "Internationa:l Conference on Harmonics and Quality of Power," Las Vegas, October 16-18, 1996, a control method for a compensation device with parallel coupling is known.
From this conference report, it can be learned that the compensator voltage space= vector is calculated from the voltage dropped at the capacitive memory and from a transmission ratio space vector. Moreover, this report teaches that the transmission ratio space vector can be composed from a plurality of sub--ratio space vectors. In addition, it is indicated how the :>ub-tr<~nsmission ratio space vectors are determined. The block switching diagram of the compensation device shown in the article is described in more detail below on the basis of the reprf~sentation according to Figure 1:
This compensation device 2 has a pulse-controlled converter 4 having at least one capacitive memory 6, a matching filter 8 and an automatic control device 10. This compensation device 2 is connected electrically parallel to a non-ideal load 12 that is supplied with power from a network 14. Automatic control device 10 is provided with a network voltage space vector uN, a line current spa~~e vector iN and an intermediate circuit voltage actual value Vd~ = 2 Ed that is dropped at two capacitive memories 6 of pulse-controlled converter 4. These space vectors u,~ and iN are generated from measured conductor --, voltages and line current values, using a space vector transformation device. Here matching filter 8 is shown replaced by an inductance LK, whereas in the cited article this matching filter 8 .is shown in detail. Automatic control device 10 has a control device 16 for determining a transmission ratio space vector a and a pulse-width modulator 18, represented by a b~=oken line. Transmission ratio space vector a is the manipulated quantity of pulse-controlled converter 4 that is converted into control signals S" for this pulse-controlled converter 4, using pulse-width modulator 18.
Changes in load cause changes of the voltage drops at the network impedances,, and thus changes in the effective value of the supply voltage.. In t:he case of asymmetrically connected loads, these voltage drops are also asymmetrical; i.e., the amplitudes and effective values of the phase voltages have different values. The essential portion of the voltage drops at the network impedance is to be attributed to the reactive current portions, since the network impedance has a ratio of reactance to resist=ance that is significantly greater than 1, as a rule. The supply changes cause changes in the luminance of (incandescent) .Lamps. The human optical perceptual apparatus perceives these changes in luminance. This phenomenon is called 'flicker.' The changes in luminance are felt to be unpleasant particularly in the region of about 18 changes per second (9 Hz). Large changes in voltage that cause the flicker effect are caused by - switching-on and switching-off processes with larger loads, e..g. motor run-up (discontinuous change of load) - alternat_Lng lo<~ds (e. g. gang saw, forging press, forging hammer) - resistance welding equipment (periodic load changes, mostly one-phase load) - arc-welding equipment - arc melt~:ng furnaces (stochastic changes in load) - pulsed tasks (e. g., burst firing control).
The causes of flicker can be divided into two classes:
1. regular c:hangea of load (such as for example in welding equipment) 2. stochastic occurrent changes of load (for example, in arc ovens).
These differences are taken into account in the evaluation of the flicker. Decisive influencing factors are magnitudes, duration and chronologic<~1 sequence of the voltage changes.
In order to keep undesirable reactive currents of load 12 away from supply network 14, compensation device 2 must feed these portions parallel t:o load 12, so that the current portions of compensation device 2 cancel with the reactive current portions of load 12 at point of common coupling 20.
For reactive current compensation and load symmetrization, up to now reactive elements -- regulated or controlled via contactors or thyristors -- connected into the network have been used, possibly with reactive elements connected permanently into the network. In this way the function of a Steinmetz circuit is emulated. However, as shown in the following, the devices have undesirable dead times due to the network management and are partially inflexible. The technology used previously for removal of flicker in low-power networks is made up of thyristor-switched capacitors (TSC) in connection with reactive elements (reactors, capacitors) that are connected permanently or in load-dependent manner between the network phases via contactors. For flicker-producing elements that are ~~onnected in two-phase manner (e. g., welding machines in low-power networks), the reactive elements effect a symmetrization for one or more operational points of the load. The reactive power is then compensated using the TSC.
Overall, with the use of this arrangement the attempt is made to emulate a highly dynamic Steinmetz circuit. In order to adequately handle changing load situations, defined compensation levels must be constructed so as to be switchable independently. The problem with this technology, used up to now in low-power nc=tworks, is that the reactive elements cannot be adapted :Flexibly to changed load situations, and the thyristors of the 'rSC can be switched only at the zero crossing of the nel~work voltages. This causes an increase in the rise time, which reduces the degree of flicker removal.
For flicker removal in medium-power networks, reactors switched into the network, regulated via thyristors (TCR =
Thyristor-Controlled Reactor), are used, in connection with LC
filter circuits. According to the load state, the TCR runs inductively againsi_ the filter circuits, which set a capacitive operating point. Such an arrangement is described in the German publication "etzArchiv," vol. 11, 1989, no. 8, pages 249 to 253. Here as well, the network-controlled thyristor power converter represents a disadvantage with regard to the control rate of the system. Moreover, the phase angle of the thyristors of the TCR causes harmonic currents.
In summary, this described compensation device includes the following features:.
- delayed, active compensation of fundamental complement reactive current and negative-phase-sequence current, - passive i=ilter:ing of harmonic currents (narrow-band) by division of the capacitor battery into filter circuits, - resistivE: attenuation of natural oscillations, e.g.
with the aid o:E resistances in the filter circuits.
The unavoidable disadvantages of the previously used reactive current measurement, methods are circumvented if the active current is determined by measurement using the dummy conductance for the load,, and this active current is subtracted from the delay-free measurable load current in order to obtain the reactive current to be compensated. A
compensation device that can compensate this current without delay is shown in more detail in the German publication "Elektrowarme Inter_national," vol. 41, 1983, B 6, December, pages B 254 to B 260. This automatic control structure for reactive current compensation and voltage stabilization (shown in more detail in t=his publication) of an arc oven has a conductance measurement device, a target value computer, a voltage controller,. a device for acquiring the harmonics, a control device, and two adders. Using the conductance measurement device,. the ~~onductance and its chronological gradient are deterrnined from the measured load voltages and load currents. The target value computer simulates the ideally compensated networ)c and forms the necessary required target value of the power converter current, with which the compensation goals is already largely achieved. The attenuation of the parallel oscillation circuit, formed from the network internal impedance and the capacitor battery, and the correction of possible imprecisions in calculation and measurement errors in the conductance measurement device and in the target value computer are effected with the aid of the voltage controller.. For 'this purpose, the measured voltage is compared with its target curve, calculated as precisely as possible. The control device responds to the difference with an additional small correction current that is added to the power converter current. The power converter is then finally controlled in a manner corresponding to the chronological curve of the sum. Since the harmonic currents of the power converter current :Largely flow via the capacitor battery, they also cause harmonies of the network voltage. Since the power converter cannot itself compensate the effect of its own harmonics, the harmonics of the network voltage are made unobservable for the voltage controller with the aid of the device for acquiring the harmonics.
This compensation device has the following technical characteristics:
- very good dynamic response during the active reactive current compensation and symmetrization in the obsei:ved frequency range, - active holding constant of the effective value of the load voltage, - passive and broadband filtering of harmonic currents, - active, 7_oss-free attenuation of natural oscillations.
This compensation device is very expensive, because its automatic control :>tructure operates in the time domain. In comparison with a compensation arrangement that uses a capacitor battery that is connected permanently into the network and a switched reactor, the compensation arrangement having a self-regu_Lated power converter has a higher dynamic response, which can be further increased. A rapid load symmetrization is not possible using this compensation arrangement.
The main goal of the rapid reactive current compensation is the avoidance of voltage fluctuations, so that other loads fed by the same network are not disturbed. As is generally known, this aim places the highest demands on the dynamic response of the compensation devices, particularly if no disturbing light flickering is supposed to occur in lighting equipment operated in parallel.
In order for a load to appear as a three-phase symmetrical ohmic resistance from the point of view of the overlay network with respect to the fundamental component, undesired fundamental component current portions from the line current, and indeed the negative-phase-sequence system load current and the positive-phase--sequence system reactive current, must be eliminated. This achieves a reduction of the flicker emission of a load in the overlay network. So that the line current no longer has any undesired fundamental-component current portions, the following portions of the load current must be compensated:
- reactive portion of the fundamental component of the positive--phase-sequence system of the current - fundament:al component of the negative-phase-sequence system of: the current .
The invention is based on the object of indicating a method and a device for improving the current quality of an overlay network.
This object is achieved according to the invention by the characterizing features of claim 1 or claim 7.
In order to improve significantly the current quality of an overlay network, the undesired fundamental component power portions, namely the negative-phase-sequence system load current and the poaitive-phase-sequence system reactive current, must be e:Liminated from the line current. For this purpose, a compensator voltage space vector is required that is made up of a cornpensator voltage fundamental component positive-phase-sequence system space vector and a compensator voltage fundamental component negative-phase-sequence system space vector. SincE~ the compensator voltage fundamental component negative--phase-sequence system space vector is determined dependent on .an identified amplitude of a line current fundamental component negative-phase-sequence system, the negative-phase--sequence system load current can be compensated. The compensator fundamental positive-phase-sequence system space ve~~tor is made up of two voltage components, of which one component runs parallel to the line voltage fundamenta:_ component positive-phase-sequence space vector and the other component runs perpendicular to this vector. Using the parallel voltage component, the determined fundamental component positive-phase-system reactive power is compensated, and using the perpendicular voltage component the intermediate circu~_t voltage actual value is controlled to a predetermined target value.
Using this inventive method, the known compensation device according to FigurE~ 1 can execute a highly dynamic load symmetrization and reactive power compensation with regard to the fundamental component currents of an arbitrary load. The advantage of this method is the independence of the manner of functioning from the type and size of the underlaid load.
Thus, from the point of ~view of the overlay network, with respect to the fundament<~1 component a load appears as a three-phase symmetrical ohmic resistance.
For the further explanation of the inventive method for improving the current quality of an overlay network using a compensation device having a pulse-controlled converter, reference is made t.o the drawing, in which an exemplary embodiment of the device for executing the inventive method is illustrated schematically.
Figure 1 shows a block switching diagram of the above-cited known cornpensation device, and Figure 2 shows a block ;switching diagram of an apparatus for executing the :inventive method.
Figure 2 shows, in greatE=r detail, a block switching diagram of an apparatus for executing the inventive method. This apparatus has an identification device 22, a computing device 24, an intermediate circuit voltage control circuit 26, a device 28 for determining complex amplitudes uK,l, and uK,l_ of a compensator voltage fundamental component positive-phase-sequence and negative-ph<~se-sequence system space vector uK,l+
and uK,l_ and a space vector formation unit 30. The determined line voltage and line current space vectors u~, and 1N are supplied to identification device 22. At the output side, this identification device 22 is connected with inputs of computing unit 24 and device 28. Likewise, at the output side computing unit 24 is connected with an input of device 28, which is, in addition, connected at the input side with an output of intermediate circuit voltage control circuit 26. The two outputs of device 28 are connected with space vector formation unit 30, to which another intermediate circuit voltage actual value Vd~ is also connected at the input side. At the output of this space vector formation unit 30 there is a transmission ratio space vector ii, from which the control signals S" for pulse-controlled converter 4 of compensation device 2 are generated using pulse width modulator 18.
In this block switching diagram, space vectors are characterized by an arrow, while complex quantities are underlined. The index 1 :indicates a fundamental component quantity, and index + or - identifies the positive-phase-sequence system or the negative-phase-sequence system. The index of parallel :>trokea or perpendicular strokes (II or 1) indicates that these complex amplitudes run in the direction of, or perpendicular to, the line voltage fundamental component positive--phase-sequence system space vector a N,1+.
The output quantities of the controller are scalar quantities.
A complex quantity with a superscripted star indicates a conjugated complex quantity.
Identification device 22 has a computing unit 32, 34 and 36 for each amplitude uN,l+, iN,~+, and iN,l_ to be identified.
Determined line vo7_tage apace vector uN is supplied to computing unit 32, and determined line current space vector 1N
-, is supplied to computing units 34 and 36. At the output of computing unit 32 there is a complex Fourier coefficient u~,,l+, having ordinal number 1 of the observed oscillation of the positive-phase-sequence system. At the output of computing unit 34 and 36, there is likewise a complex Fourier coefficient iN,l+ and i~,,l_, respectively. Each complex Fourier coefficient contains information about the magnitude and phase position of the quantity to be identified, in relation to a reference space vector (unit space vector). For this reason, in the following these calculated complex Fourier coefficients urr,~+. irr,l+. and iN,l_ are called amplitudes. These complex Fourier coefficients are obtained using a discrete complex Fourier transformation. A block switching diagram of a discrete complex Fourier transformation is illustrated in the above-cited conference report. This discrete Fourier transformation is made up of a complex multiplication with subsequent mean value formation. In the complex multiplication, the space vector to be identified .is multiplied by a unit space vector, and the complex product .is averaged over a period of the space vector to be identified. With respect to the dynamic response, here averaging takes place over a half period. For the identification of this discrete complex Fourier transformation, the. corresponding equations are indicated in computing units 32, 34, and 36. At the outputs of this identification device 22 there are thus available the complex amplitude uN,l+ of the line voltage fundamental component positive-phase-sequence system, the complex amplitude iN,l+ of the line current fundamental component positive-phase-sequence system, and the complex amplitude iN,l_ of the line current fundamental component negative-phase-sequence system.
The outputs of ider.,tification device 22, at which complex amplitudes u~,,l+ and iN,l+ of the fundamental component positive-phase-sequence system arE: available, are connected with the inputs of computing' unit 24. The output of identification unit 22, at which complex amp7_itude iN,l_ of the fundamental component negative-phase-sequence system is available, is connected with a second input of device 28 for determining complex amplitudes uK,l+ and uK,l_ of a compensator voltage fundamental component positive-phase-sequence and negative-phase-sequence system. From the available fundamental component positive-phase-sequence system portions uN,l+ and iN,l+, computing unii~ 24 calculates a positive-phase-sequence system fundamental component reactive power q~,,l, -- which is supplied to a first: input of the downstream device 28 --according to the following equation:
qN; ~+ _ ( 3 / 2 ) ~ Im { L~_r~, ~+ ' i. *~,, ~+
In order to compensate the fundamental component positive-phase-sequence syst:em reactive current, this calculated positive-phase-sequence system fundamental component reactive power q~,,~+ must be ~zontrolled to zero. For this purpose, device 28 has a first PI controller 38, which is connected at the input side with the first input of this device 28. At the output of this PI controller 38 there is a reactive power manipulated quantity Sqy as a controller output quantity, which is multiplied with determined complex amplitude u,~,l+ of the line voltage basic system, using a first multiplication unit 40. At the output of this first multiplier 40, which is connected with an input of an adder 42, there is a voltage amplitude uK,l+ii of a compensator voltage fundamental component positive-phase-sequence system space vector uK,l+, this amplitude running parallel to amplitude uN,l+ of line voltage fundamental component positive-phase-sequence system space vector a N,1+. Using this voltage amplitude uK,l+~ i. with the aid of matching filter 8 a portion is produced in the current iN
that is perpendicular to the positive-phase-sequence system line voltage u~,,l+, and in this way positive-phase-sequence system fundamental component reactive power qN,l+ is controlled to zero.
A second PI controller 44 is connected downstream from the second input of device 28, and a current manipulated quantity Sly is available at the output of this controller as a controller output quantity. This scalar current manipulated quantity Siy is multiplied with negative imaginary unit -j using a second multiplication unit 46, and in this way the current manipulated quantity Siy is rotated by -90°. The sign of imaginary unit j depends on the reference arrow system used. Since in Figure 1 the load reference arrow system is used, imaginary unit j is negative. At the output of this second multiplier ~l6 there is a complex amplitude uK,l_ of a compensator voltage fundamental component negative-phase-sequence system space vector uK,l_, with which the fundamental component negative-phase-sequence system in line current 1N is controlled to zero.
In addition, this device 28 also has a device 48 with which a voltage amplitude 1.1 K,l+1 of compensator voltage fundamental component positive-phase-sequence system space vector uK,l+ is generated, which runs perpendicular to amplitude u~,,l+ of line voltage fundamental component positive-phase-sequence system space vector uN,l+. ,his device 48 has two multipliers 50 and 52 that are switched one after the other. The second input of multiplier 52 is connected with the output of intermediate circuit voltage control circuit 26, at whose output there is an intermediate circuit manipulated quantity Sd~y. The one input of multiplier 50 is connected with the first output of identification device 22, a negative imaginary unit -j being available at the second input thereof. Since according to Figure 1 the load reference arrow system is used, multiplication takes place by negative imaginary unit j. Using this multiplier 50, complex amplitude uN,l+ is rotated by -90°, and this amplitude is subsequently multiplied by intermediate circuit manipulated quantity Say. Voltage amplitude uK,l+1 of compensator voltage fundamental component positive-phase-sequence system space vector uK,l+ is then available at the output of this mult:iplie:r 52, and this amplitude controls a determined intermediate circuit voltage difference ~Va~ to zero.
Intermediate circu:_t manipulated quantity Saw is determined using intermediate circuit voltage control circuit 26. For this purpose, this control circuit 26 has at the input side a comparator 54 at whose non-inverting input there is available an intermediate circuit voltage target value Va~soll and at whose inverting input there is available a determined intermediate circuit voltage act:ual v<~lue Va~. At the output of this comparator 54 there is available an intermediate circuit voltage difference ~Va~. 'This control deviation ~Va~ is smoothed using a first-order. delay element 56, before being amplified using a P-controller 58. This smoothing of the control deviation ~Va~ is required because, due to the load symmetrization, int:ermed_Late circuit voltage actual value Va generally contains an alt=ernating portion having twice the network frequency, and this alternating portion must not be amplified by P-cont:roller_ 58. An I-controller 60, connected at the input side with the output of comparator 54, removes the remaining control deviat_Lon that would arise given the exclusive use of a P-cont=roller 58. The controller output quantities of I- and P-controllers 60 and 58 are superposed, using an adder 62, to form intermediate circuit manipulated quantity Sa~Y.
Output-side space vector formation unit 30 has at the input side two multiplication units 64 and 66 that are each connected at the output side with a respective input of an adder 68. At the output aide, this adder 68 is connected with a second multiplier 70 whose second input is connected with the output of a reciprocal formation unit 72, at whose input there is available a determined intermediate circuit voltage actual value Vd~. The output of additional multiplier 70, at which there is available a transmission ratio space vector Li, _-, is connected with pulse-width modulator 18 of automatic control device 10 of pulse-controlled converter 4, said modulator generating -- dependent on this transmission ratio space vector ii -- control signals S~ for pulse-controlled converter 4, so that this pulse-controlled converter 4 generates determined compensator voltage fundamental component space vector uK,l. Input--side multipliers 64 and 66 of this space vector format=ion unit 30 are each connected with an output of device 28, at which there is available a complex amplitude uK,l+ and uK,l_ of a compensator voltage fundamental component positive--phase-sequence system and negative-phase-sequence system space vector a K,1+ and a K,1_, respectively. In order to form the positive-phase-sequence system and negative-phase-sequence system space vectors a K,1+ and a K,1_ from these --, determined amplitudes uK,l+ and uK,l_, these complex amplitudes uK,l+ and uK,l_ are multiplied with a unit space vector a+'"t and e-'"tof the positive-phase-sequence system and negative-phase-sequence system. The superposition of these compensator voltage fundamental- component positive-phase-sequence system and negative-phase--sequence system space vectors a K,1+ and a K,1-->
yields the compensator voltage space vector uK,l, which the pulse-controlled converter 4 must generate in order to control to zero the calculated positive-phase-sequence system fundamental component reactive power qN,l+, the fundamental component negative--phase-sequence system in the line current 1N, and the intermediate circuit voltage difference ~Vd~~
In this way, a method is obtained for a compensation device 2 having a pulse-controlled converter 4 that has at least one capacitive memory Ei that is coupled parallel to the network 14, with which a highly dynamic load symmetrization and reactive power compensat_Lon is achieved. Using this highly dynamic load symmet:rization and reactive power compensation, undesirable change; in line voltage that cause flicker are avoided to the greatest possible extent. That is, with respect to the fundamental component the load itself appears, from the point of view of overlay network 14, as a three-phase symmetrical ohmic resistance.
METHOD AND DEVICE FOR IMPROVING THE CURRENT QUALITY OF AN
cJVERLAY NETWORK
Specification The invention relai=es to a method and a device for improving the current quality of an overlay network using a compensation device coupled parallel to the network, said compensation device having a pu:Lse-controlled converter having at least one capacitive memory, a matching filter and an automatic control device, a transmission ratio space vector being determined dependent on a determined line voltage space vector and line current space vector and on an intermediate circuit voltage, control signals for the pulse-controlled converter being generated from the transmission ratio space vector.
From the publication "Shunt-Connected Power Conditioner for Improvement of Power Qua:Lity in Distribution Networks,"
printed in "Internationa:l Conference on Harmonics and Quality of Power," Las Vegas, October 16-18, 1996, a control method for a compensation device with parallel coupling is known.
From this conference report, it can be learned that the compensator voltage space= vector is calculated from the voltage dropped at the capacitive memory and from a transmission ratio space vector. Moreover, this report teaches that the transmission ratio space vector can be composed from a plurality of sub--ratio space vectors. In addition, it is indicated how the :>ub-tr<~nsmission ratio space vectors are determined. The block switching diagram of the compensation device shown in the article is described in more detail below on the basis of the reprf~sentation according to Figure 1:
This compensation device 2 has a pulse-controlled converter 4 having at least one capacitive memory 6, a matching filter 8 and an automatic control device 10. This compensation device 2 is connected electrically parallel to a non-ideal load 12 that is supplied with power from a network 14. Automatic control device 10 is provided with a network voltage space vector uN, a line current spa~~e vector iN and an intermediate circuit voltage actual value Vd~ = 2 Ed that is dropped at two capacitive memories 6 of pulse-controlled converter 4. These space vectors u,~ and iN are generated from measured conductor --, voltages and line current values, using a space vector transformation device. Here matching filter 8 is shown replaced by an inductance LK, whereas in the cited article this matching filter 8 .is shown in detail. Automatic control device 10 has a control device 16 for determining a transmission ratio space vector a and a pulse-width modulator 18, represented by a b~=oken line. Transmission ratio space vector a is the manipulated quantity of pulse-controlled converter 4 that is converted into control signals S" for this pulse-controlled converter 4, using pulse-width modulator 18.
Changes in load cause changes of the voltage drops at the network impedances,, and thus changes in the effective value of the supply voltage.. In t:he case of asymmetrically connected loads, these voltage drops are also asymmetrical; i.e., the amplitudes and effective values of the phase voltages have different values. The essential portion of the voltage drops at the network impedance is to be attributed to the reactive current portions, since the network impedance has a ratio of reactance to resist=ance that is significantly greater than 1, as a rule. The supply changes cause changes in the luminance of (incandescent) .Lamps. The human optical perceptual apparatus perceives these changes in luminance. This phenomenon is called 'flicker.' The changes in luminance are felt to be unpleasant particularly in the region of about 18 changes per second (9 Hz). Large changes in voltage that cause the flicker effect are caused by - switching-on and switching-off processes with larger loads, e..g. motor run-up (discontinuous change of load) - alternat_Lng lo<~ds (e. g. gang saw, forging press, forging hammer) - resistance welding equipment (periodic load changes, mostly one-phase load) - arc-welding equipment - arc melt~:ng furnaces (stochastic changes in load) - pulsed tasks (e. g., burst firing control).
The causes of flicker can be divided into two classes:
1. regular c:hangea of load (such as for example in welding equipment) 2. stochastic occurrent changes of load (for example, in arc ovens).
These differences are taken into account in the evaluation of the flicker. Decisive influencing factors are magnitudes, duration and chronologic<~1 sequence of the voltage changes.
In order to keep undesirable reactive currents of load 12 away from supply network 14, compensation device 2 must feed these portions parallel t:o load 12, so that the current portions of compensation device 2 cancel with the reactive current portions of load 12 at point of common coupling 20.
For reactive current compensation and load symmetrization, up to now reactive elements -- regulated or controlled via contactors or thyristors -- connected into the network have been used, possibly with reactive elements connected permanently into the network. In this way the function of a Steinmetz circuit is emulated. However, as shown in the following, the devices have undesirable dead times due to the network management and are partially inflexible. The technology used previously for removal of flicker in low-power networks is made up of thyristor-switched capacitors (TSC) in connection with reactive elements (reactors, capacitors) that are connected permanently or in load-dependent manner between the network phases via contactors. For flicker-producing elements that are ~~onnected in two-phase manner (e. g., welding machines in low-power networks), the reactive elements effect a symmetrization for one or more operational points of the load. The reactive power is then compensated using the TSC.
Overall, with the use of this arrangement the attempt is made to emulate a highly dynamic Steinmetz circuit. In order to adequately handle changing load situations, defined compensation levels must be constructed so as to be switchable independently. The problem with this technology, used up to now in low-power nc=tworks, is that the reactive elements cannot be adapted :Flexibly to changed load situations, and the thyristors of the 'rSC can be switched only at the zero crossing of the nel~work voltages. This causes an increase in the rise time, which reduces the degree of flicker removal.
For flicker removal in medium-power networks, reactors switched into the network, regulated via thyristors (TCR =
Thyristor-Controlled Reactor), are used, in connection with LC
filter circuits. According to the load state, the TCR runs inductively againsi_ the filter circuits, which set a capacitive operating point. Such an arrangement is described in the German publication "etzArchiv," vol. 11, 1989, no. 8, pages 249 to 253. Here as well, the network-controlled thyristor power converter represents a disadvantage with regard to the control rate of the system. Moreover, the phase angle of the thyristors of the TCR causes harmonic currents.
In summary, this described compensation device includes the following features:.
- delayed, active compensation of fundamental complement reactive current and negative-phase-sequence current, - passive i=ilter:ing of harmonic currents (narrow-band) by division of the capacitor battery into filter circuits, - resistivE: attenuation of natural oscillations, e.g.
with the aid o:E resistances in the filter circuits.
The unavoidable disadvantages of the previously used reactive current measurement, methods are circumvented if the active current is determined by measurement using the dummy conductance for the load,, and this active current is subtracted from the delay-free measurable load current in order to obtain the reactive current to be compensated. A
compensation device that can compensate this current without delay is shown in more detail in the German publication "Elektrowarme Inter_national," vol. 41, 1983, B 6, December, pages B 254 to B 260. This automatic control structure for reactive current compensation and voltage stabilization (shown in more detail in t=his publication) of an arc oven has a conductance measurement device, a target value computer, a voltage controller,. a device for acquiring the harmonics, a control device, and two adders. Using the conductance measurement device,. the ~~onductance and its chronological gradient are deterrnined from the measured load voltages and load currents. The target value computer simulates the ideally compensated networ)c and forms the necessary required target value of the power converter current, with which the compensation goals is already largely achieved. The attenuation of the parallel oscillation circuit, formed from the network internal impedance and the capacitor battery, and the correction of possible imprecisions in calculation and measurement errors in the conductance measurement device and in the target value computer are effected with the aid of the voltage controller.. For 'this purpose, the measured voltage is compared with its target curve, calculated as precisely as possible. The control device responds to the difference with an additional small correction current that is added to the power converter current. The power converter is then finally controlled in a manner corresponding to the chronological curve of the sum. Since the harmonic currents of the power converter current :Largely flow via the capacitor battery, they also cause harmonies of the network voltage. Since the power converter cannot itself compensate the effect of its own harmonics, the harmonics of the network voltage are made unobservable for the voltage controller with the aid of the device for acquiring the harmonics.
This compensation device has the following technical characteristics:
- very good dynamic response during the active reactive current compensation and symmetrization in the obsei:ved frequency range, - active holding constant of the effective value of the load voltage, - passive and broadband filtering of harmonic currents, - active, 7_oss-free attenuation of natural oscillations.
This compensation device is very expensive, because its automatic control :>tructure operates in the time domain. In comparison with a compensation arrangement that uses a capacitor battery that is connected permanently into the network and a switched reactor, the compensation arrangement having a self-regu_Lated power converter has a higher dynamic response, which can be further increased. A rapid load symmetrization is not possible using this compensation arrangement.
The main goal of the rapid reactive current compensation is the avoidance of voltage fluctuations, so that other loads fed by the same network are not disturbed. As is generally known, this aim places the highest demands on the dynamic response of the compensation devices, particularly if no disturbing light flickering is supposed to occur in lighting equipment operated in parallel.
In order for a load to appear as a three-phase symmetrical ohmic resistance from the point of view of the overlay network with respect to the fundamental component, undesired fundamental component current portions from the line current, and indeed the negative-phase-sequence system load current and the positive-phase--sequence system reactive current, must be eliminated. This achieves a reduction of the flicker emission of a load in the overlay network. So that the line current no longer has any undesired fundamental-component current portions, the following portions of the load current must be compensated:
- reactive portion of the fundamental component of the positive--phase-sequence system of the current - fundament:al component of the negative-phase-sequence system of: the current .
The invention is based on the object of indicating a method and a device for improving the current quality of an overlay network.
This object is achieved according to the invention by the characterizing features of claim 1 or claim 7.
In order to improve significantly the current quality of an overlay network, the undesired fundamental component power portions, namely the negative-phase-sequence system load current and the poaitive-phase-sequence system reactive current, must be e:Liminated from the line current. For this purpose, a compensator voltage space vector is required that is made up of a cornpensator voltage fundamental component positive-phase-sequence system space vector and a compensator voltage fundamental component negative-phase-sequence system space vector. SincE~ the compensator voltage fundamental component negative--phase-sequence system space vector is determined dependent on .an identified amplitude of a line current fundamental component negative-phase-sequence system, the negative-phase--sequence system load current can be compensated. The compensator fundamental positive-phase-sequence system space ve~~tor is made up of two voltage components, of which one component runs parallel to the line voltage fundamenta:_ component positive-phase-sequence space vector and the other component runs perpendicular to this vector. Using the parallel voltage component, the determined fundamental component positive-phase-system reactive power is compensated, and using the perpendicular voltage component the intermediate circu~_t voltage actual value is controlled to a predetermined target value.
Using this inventive method, the known compensation device according to FigurE~ 1 can execute a highly dynamic load symmetrization and reactive power compensation with regard to the fundamental component currents of an arbitrary load. The advantage of this method is the independence of the manner of functioning from the type and size of the underlaid load.
Thus, from the point of ~view of the overlay network, with respect to the fundament<~1 component a load appears as a three-phase symmetrical ohmic resistance.
For the further explanation of the inventive method for improving the current quality of an overlay network using a compensation device having a pulse-controlled converter, reference is made t.o the drawing, in which an exemplary embodiment of the device for executing the inventive method is illustrated schematically.
Figure 1 shows a block switching diagram of the above-cited known cornpensation device, and Figure 2 shows a block ;switching diagram of an apparatus for executing the :inventive method.
Figure 2 shows, in greatE=r detail, a block switching diagram of an apparatus for executing the inventive method. This apparatus has an identification device 22, a computing device 24, an intermediate circuit voltage control circuit 26, a device 28 for determining complex amplitudes uK,l, and uK,l_ of a compensator voltage fundamental component positive-phase-sequence and negative-ph<~se-sequence system space vector uK,l+
and uK,l_ and a space vector formation unit 30. The determined line voltage and line current space vectors u~, and 1N are supplied to identification device 22. At the output side, this identification device 22 is connected with inputs of computing unit 24 and device 28. Likewise, at the output side computing unit 24 is connected with an input of device 28, which is, in addition, connected at the input side with an output of intermediate circuit voltage control circuit 26. The two outputs of device 28 are connected with space vector formation unit 30, to which another intermediate circuit voltage actual value Vd~ is also connected at the input side. At the output of this space vector formation unit 30 there is a transmission ratio space vector ii, from which the control signals S" for pulse-controlled converter 4 of compensation device 2 are generated using pulse width modulator 18.
In this block switching diagram, space vectors are characterized by an arrow, while complex quantities are underlined. The index 1 :indicates a fundamental component quantity, and index + or - identifies the positive-phase-sequence system or the negative-phase-sequence system. The index of parallel :>trokea or perpendicular strokes (II or 1) indicates that these complex amplitudes run in the direction of, or perpendicular to, the line voltage fundamental component positive--phase-sequence system space vector a N,1+.
The output quantities of the controller are scalar quantities.
A complex quantity with a superscripted star indicates a conjugated complex quantity.
Identification device 22 has a computing unit 32, 34 and 36 for each amplitude uN,l+, iN,~+, and iN,l_ to be identified.
Determined line vo7_tage apace vector uN is supplied to computing unit 32, and determined line current space vector 1N
-, is supplied to computing units 34 and 36. At the output of computing unit 32 there is a complex Fourier coefficient u~,,l+, having ordinal number 1 of the observed oscillation of the positive-phase-sequence system. At the output of computing unit 34 and 36, there is likewise a complex Fourier coefficient iN,l+ and i~,,l_, respectively. Each complex Fourier coefficient contains information about the magnitude and phase position of the quantity to be identified, in relation to a reference space vector (unit space vector). For this reason, in the following these calculated complex Fourier coefficients urr,~+. irr,l+. and iN,l_ are called amplitudes. These complex Fourier coefficients are obtained using a discrete complex Fourier transformation. A block switching diagram of a discrete complex Fourier transformation is illustrated in the above-cited conference report. This discrete Fourier transformation is made up of a complex multiplication with subsequent mean value formation. In the complex multiplication, the space vector to be identified .is multiplied by a unit space vector, and the complex product .is averaged over a period of the space vector to be identified. With respect to the dynamic response, here averaging takes place over a half period. For the identification of this discrete complex Fourier transformation, the. corresponding equations are indicated in computing units 32, 34, and 36. At the outputs of this identification device 22 there are thus available the complex amplitude uN,l+ of the line voltage fundamental component positive-phase-sequence system, the complex amplitude iN,l+ of the line current fundamental component positive-phase-sequence system, and the complex amplitude iN,l_ of the line current fundamental component negative-phase-sequence system.
The outputs of ider.,tification device 22, at which complex amplitudes u~,,l+ and iN,l+ of the fundamental component positive-phase-sequence system arE: available, are connected with the inputs of computing' unit 24. The output of identification unit 22, at which complex amp7_itude iN,l_ of the fundamental component negative-phase-sequence system is available, is connected with a second input of device 28 for determining complex amplitudes uK,l+ and uK,l_ of a compensator voltage fundamental component positive-phase-sequence and negative-phase-sequence system. From the available fundamental component positive-phase-sequence system portions uN,l+ and iN,l+, computing unii~ 24 calculates a positive-phase-sequence system fundamental component reactive power q~,,l, -- which is supplied to a first: input of the downstream device 28 --according to the following equation:
qN; ~+ _ ( 3 / 2 ) ~ Im { L~_r~, ~+ ' i. *~,, ~+
In order to compensate the fundamental component positive-phase-sequence syst:em reactive current, this calculated positive-phase-sequence system fundamental component reactive power q~,,~+ must be ~zontrolled to zero. For this purpose, device 28 has a first PI controller 38, which is connected at the input side with the first input of this device 28. At the output of this PI controller 38 there is a reactive power manipulated quantity Sqy as a controller output quantity, which is multiplied with determined complex amplitude u,~,l+ of the line voltage basic system, using a first multiplication unit 40. At the output of this first multiplier 40, which is connected with an input of an adder 42, there is a voltage amplitude uK,l+ii of a compensator voltage fundamental component positive-phase-sequence system space vector uK,l+, this amplitude running parallel to amplitude uN,l+ of line voltage fundamental component positive-phase-sequence system space vector a N,1+. Using this voltage amplitude uK,l+~ i. with the aid of matching filter 8 a portion is produced in the current iN
that is perpendicular to the positive-phase-sequence system line voltage u~,,l+, and in this way positive-phase-sequence system fundamental component reactive power qN,l+ is controlled to zero.
A second PI controller 44 is connected downstream from the second input of device 28, and a current manipulated quantity Sly is available at the output of this controller as a controller output quantity. This scalar current manipulated quantity Siy is multiplied with negative imaginary unit -j using a second multiplication unit 46, and in this way the current manipulated quantity Siy is rotated by -90°. The sign of imaginary unit j depends on the reference arrow system used. Since in Figure 1 the load reference arrow system is used, imaginary unit j is negative. At the output of this second multiplier ~l6 there is a complex amplitude uK,l_ of a compensator voltage fundamental component negative-phase-sequence system space vector uK,l_, with which the fundamental component negative-phase-sequence system in line current 1N is controlled to zero.
In addition, this device 28 also has a device 48 with which a voltage amplitude 1.1 K,l+1 of compensator voltage fundamental component positive-phase-sequence system space vector uK,l+ is generated, which runs perpendicular to amplitude u~,,l+ of line voltage fundamental component positive-phase-sequence system space vector uN,l+. ,his device 48 has two multipliers 50 and 52 that are switched one after the other. The second input of multiplier 52 is connected with the output of intermediate circuit voltage control circuit 26, at whose output there is an intermediate circuit manipulated quantity Sd~y. The one input of multiplier 50 is connected with the first output of identification device 22, a negative imaginary unit -j being available at the second input thereof. Since according to Figure 1 the load reference arrow system is used, multiplication takes place by negative imaginary unit j. Using this multiplier 50, complex amplitude uN,l+ is rotated by -90°, and this amplitude is subsequently multiplied by intermediate circuit manipulated quantity Say. Voltage amplitude uK,l+1 of compensator voltage fundamental component positive-phase-sequence system space vector uK,l+ is then available at the output of this mult:iplie:r 52, and this amplitude controls a determined intermediate circuit voltage difference ~Va~ to zero.
Intermediate circu:_t manipulated quantity Saw is determined using intermediate circuit voltage control circuit 26. For this purpose, this control circuit 26 has at the input side a comparator 54 at whose non-inverting input there is available an intermediate circuit voltage target value Va~soll and at whose inverting input there is available a determined intermediate circuit voltage act:ual v<~lue Va~. At the output of this comparator 54 there is available an intermediate circuit voltage difference ~Va~. 'This control deviation ~Va~ is smoothed using a first-order. delay element 56, before being amplified using a P-controller 58. This smoothing of the control deviation ~Va~ is required because, due to the load symmetrization, int:ermed_Late circuit voltage actual value Va generally contains an alt=ernating portion having twice the network frequency, and this alternating portion must not be amplified by P-cont:roller_ 58. An I-controller 60, connected at the input side with the output of comparator 54, removes the remaining control deviat_Lon that would arise given the exclusive use of a P-cont=roller 58. The controller output quantities of I- and P-controllers 60 and 58 are superposed, using an adder 62, to form intermediate circuit manipulated quantity Sa~Y.
Output-side space vector formation unit 30 has at the input side two multiplication units 64 and 66 that are each connected at the output side with a respective input of an adder 68. At the output aide, this adder 68 is connected with a second multiplier 70 whose second input is connected with the output of a reciprocal formation unit 72, at whose input there is available a determined intermediate circuit voltage actual value Vd~. The output of additional multiplier 70, at which there is available a transmission ratio space vector Li, _-, is connected with pulse-width modulator 18 of automatic control device 10 of pulse-controlled converter 4, said modulator generating -- dependent on this transmission ratio space vector ii -- control signals S~ for pulse-controlled converter 4, so that this pulse-controlled converter 4 generates determined compensator voltage fundamental component space vector uK,l. Input--side multipliers 64 and 66 of this space vector format=ion unit 30 are each connected with an output of device 28, at which there is available a complex amplitude uK,l+ and uK,l_ of a compensator voltage fundamental component positive--phase-sequence system and negative-phase-sequence system space vector a K,1+ and a K,1_, respectively. In order to form the positive-phase-sequence system and negative-phase-sequence system space vectors a K,1+ and a K,1_ from these --, determined amplitudes uK,l+ and uK,l_, these complex amplitudes uK,l+ and uK,l_ are multiplied with a unit space vector a+'"t and e-'"tof the positive-phase-sequence system and negative-phase-sequence system. The superposition of these compensator voltage fundamental- component positive-phase-sequence system and negative-phase--sequence system space vectors a K,1+ and a K,1-->
yields the compensator voltage space vector uK,l, which the pulse-controlled converter 4 must generate in order to control to zero the calculated positive-phase-sequence system fundamental component reactive power qN,l+, the fundamental component negative--phase-sequence system in the line current 1N, and the intermediate circuit voltage difference ~Vd~~
In this way, a method is obtained for a compensation device 2 having a pulse-controlled converter 4 that has at least one capacitive memory Ei that is coupled parallel to the network 14, with which a highly dynamic load symmetrization and reactive power compensat_Lon is achieved. Using this highly dynamic load symmet:rization and reactive power compensation, undesirable change; in line voltage that cause flicker are avoided to the greatest possible extent. That is, with respect to the fundamental component the load itself appears, from the point of view of overlay network 14, as a three-phase symmetrical ohmic resistance.
Claims (11)
1. A method for improving the current quality of an overlay network (14) using a compensation device (2) coupled parallel to the network (14), the compensation device having a pulse-controlled converter (4) having at least one capacitive memory (6), a matching filter (8) and an automatic control device (10), a transmission ratio space vector (~) being determined dependent on a determined line voltage space vector and line current space vector (~ N, ~ N) and on an intermediate circuit voltage actual value (V dc), control signals (S v) for the pulse-controlled converter (4) being generated from this transmission ratio space vector, characterized in that k) from the determined line voltage and line current space vectors (~ N, ~ N), a positive-phase-sequence system fundamental component reactive power (q N,~+) and a complex amplitude (i N,~-) of a line current fundamental amplitude negative-phase-sequence system are determined, l) from this determined positive-phase-sequence fundamental component reactive power (q N,~+) and from a determined intermediate circuit voltage difference (.DELTA.V dc), complex amplitudes (u K,~+~~, u K,~+~) [...] a compensator voltage component that runs parallel and perpendicular to the line voltage fundamental component positive-phase-sequence system space vector (~ N,~,+) are determined, dependent on a determined complex amplitude (u N,~+) of a fundamental component line voltage positive-phase-sequence system, m) from these determined complex amplitudes (u K,~+~~, u K,~+~) of the parallel and perpendicular compensator voltage components, and from a determined complex amplitude (u K,~-), a compensator fundamental component positive-phase-sequence system and negative-phase-sequence system space vector (~ K,~+ , ~ K,~-) are determined that, when superposed, yield a compensator fundamental component space vector (~ K,~) , and n) this determined compensator voltage fundamental component space vector (u K,~), divided by the intermediate circuit voltage actual value (V dc), yields the transmission ratio space vector (~).
2. The method according to claim 1, in which, using a discrete complex Fourier transformation and subsequent mean value formation, complex amplitudes (u N,~+ i N,~+) of a fundamental component positive--phase-sequence system are calculated from the determined line voltage and line current space vectors (~N, ~N), and the positive-phase-sequence system fundamental component reactive power (q N,~+) is subsequently calculated using these amplitudes, according to the following equation:
q N,~+ = (3/2) ~ Im { u N,~+ ~ i N,~+ }.
q N,~+ = (3/2) ~ Im { u N,~+ ~ i N,~+ }.
3. Method according to claim 1, in which a scalar reactive power manipulated quantity (S qy) is produced from the calculated positive-phase-sequence system fundamental component reactive power (q N,~+), said manipulated quantity yielding, when multiplied with the complex amplitude (u N,~+) of the line voltage fundamental component positive-phase-sequence system, the complex amplitude (u K,~+~~) of the parallel compensator voltage component.
4. The method according to claim 1, in which a scalar current manipulated quantity (S iy) is produced from the determined complex amplitude (i N,~-) of a line current fundamental component negative-phase-sequence system, said manipulated quantity yielding, when multiplied with an imaginary unit (-j), the complex amplitude (u K,~-) of the compensator voltage fundamental component negative-phase-sequence system.
5. The method according to claim 1, in which an intermediate circuit manipulated quantity (S dcy) is produced from the determined intermediate circuit voltage difference (.DELTA.V dc), said manipulated quantity yielding, when multiplied with a product of the complex amplitude (u N,~+) of the line voltage fundamental component positive-phase-sequence system and an imaginary unit (-j), the complex amplitude (u K,~+~) of the perpendicular compensator voltage component.
6. The method according to claim 1, in which the compensator voltage fundamental component positive-phase-sequence and negative-phase-sequence system space vectors (~ K,~+ , ~ k,~-) are respectively produced by a multiplication of the complex amplitudes (u K,~ + , u K,~-) of the compensator voltage fundamental component positive-phase-sequence and negative-phase-sequence system with a complex unit space vector (e +j.omega.t , e-j.omega.t).
7. A device for executing the method according to claim 1 for a [...] using a compensation device (2) coupled parallel to the network (14), having a pulse-controlled converter (4) that has at least one capacitive memory (6), a matching filter (8) and an automatic control device (10), said automatic control device (10) having a regulating device (16) for determining a transmission ratio space vector (~) using a downstream pulse-width modulator (18), at whose outputs the control signals (S v) of the pulse-controlled converter (4) are available, characterized in that this regulation device (16) has an identification device (22) for determining complex amplitudes (u N,~+ , i N,~+ , i N,~-) the line voltage and line current space vector (~ N, ~ N,) determined at the input side are supplied [sic]1, a computing unit (24) for calculating the positive-phase-sequence system fundamental component reactive power (q N,~+), said unit being connected at the input side with the identification device (22), an intermediate circuit voltage control circuit (26), a device (28) for determining complex amplitudes (u K,~+, u K,~-) of a compensator voltage basic component positive-phase-sequence and negative-phase-sequence system space vector (u K,~+
, ~K,~-), said device being connected at the input side with outputs of the identification device (22), the computing unit (24) and the intermediate circuit voltage control circuit (26), and a space vector formation unit (30) that is connected at the input side with the device (28) and an intermediate circuit voltage actual value (V dc) is available [sic].
, ~K,~-), said device being connected at the input side with outputs of the identification device (22), the computing unit (24) and the intermediate circuit voltage control circuit (26), and a space vector formation unit (30) that is connected at the input side with the device (28) and an intermediate circuit voltage actual value (V dc) is available [sic].
8. The device according to claim 7, in which the identification device (22) for determining complex amplitudes (u N,~+ , i N,~+ , i N,~-) has a computing unit (32, 34, 36) for each amplitude calculation.
9. The device according to claim 7, in which the device (28) for determining complex amplitudes (u K,~+ , u K,~-) of a compensator voltage fundamental component positive-phase-sequence and negative-phase-sequence system has two PI
controllers (38, 44), four multipliers (40, 46, 50, 52), and an adder (42), a first PI controller (38) being connected at the input side with the output of the computing unit (24) for the calculation of the positive-phase-sequence system fundamental component reactive power (q n,~+) and being connected at the output side, using a first multiplier (40), with a first input of the adder (42), the second input of this multiplier (40) and of this adder (42) being connected with a first output of the identification device (22), the second PI
controller (44) being connected at the input side with a third output of the identification device (22) and at the output side with an input of a second multiplier (46), at whose second input there is available an imaginary unit (-j), and whose output is the second output of this device (28), the first output of the identification device (22) being connected with an input of a third multiplier (50), at whose second input there is available an imaginary unit (-j), and the output of the third multiplier (50) being connected with an input of a fourth multiplier (52), whose second input is connected with an output of the intermediate circuit voltage control circuit (26), and whose output is connected with an additional input of the adder (42), whose output is a first output of this device (28).
controllers (38, 44), four multipliers (40, 46, 50, 52), and an adder (42), a first PI controller (38) being connected at the input side with the output of the computing unit (24) for the calculation of the positive-phase-sequence system fundamental component reactive power (q n,~+) and being connected at the output side, using a first multiplier (40), with a first input of the adder (42), the second input of this multiplier (40) and of this adder (42) being connected with a first output of the identification device (22), the second PI
controller (44) being connected at the input side with a third output of the identification device (22) and at the output side with an input of a second multiplier (46), at whose second input there is available an imaginary unit (-j), and whose output is the second output of this device (28), the first output of the identification device (22) being connected with an input of a third multiplier (50), at whose second input there is available an imaginary unit (-j), and the output of the third multiplier (50) being connected with an input of a fourth multiplier (52), whose second input is connected with an output of the intermediate circuit voltage control circuit (26), and whose output is connected with an additional input of the adder (42), whose output is a first output of this device (28).
10. The device according to claim 7, in which the space vector formation unit (30) has at the input side two multipliers (64, 66) that are connected, with one input respectively, with the first and second output of the device (28), a unit space vector (e+j.omega.t , e-j.omega.t) being available at the second input of each of these multipliers (64, 66), and the outputs of these multipliers (64, 66) being connected, using an adder (68), with an input of an additional multiplier (70), whose second input is connected with a reciprocal formation unit (72), at whose input there us available an intermediate circuit voltage actual value (V dc), and at whose output there is available the transmission ratio space vector (~).
11. The device according to claim 7, in which a microprocessor is provided for the control device (16).
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19734722A DE19734722C2 (en) | 1997-08-11 | 1997-08-11 | Method and device for improving the power quality of a superimposed network |
| DE19734722.3 | 1997-08-11 | ||
| PCT/DE1998/002106 WO1999008357A2 (en) | 1997-08-11 | 1998-07-27 | Method and device for improving the current quality of a superimposed network |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2300306A1 true CA2300306A1 (en) | 1999-02-18 |
Family
ID=7838621
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002300306A Abandoned CA2300306A1 (en) | 1997-08-11 | 1998-07-27 | Method and device for improving the current quality of an overlay network |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP1002353B1 (en) |
| JP (1) | JP2001512956A (en) |
| AT (1) | ATE229703T1 (en) |
| CA (1) | CA2300306A1 (en) |
| DE (2) | DE19734722C2 (en) |
| NO (1) | NO20000710L (en) |
| WO (1) | WO1999008357A2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR3057405A1 (en) * | 2016-10-11 | 2018-04-13 | Institut National Polytechnique De Toulouse | METHOD FOR CONTROLLING PARALLEL ACTIVE FILTER FOR DISTURBED NETWORKS AND ASSOCIATED ACTIVE FILTER |
| EP3813218A1 (en) | 2019-10-25 | 2021-04-28 | Wobben Properties GmbH | Arrangement for feeding electric power into an electricity supply network |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2434846T3 (en) * | 2005-12-30 | 2013-12-17 | Abb Technology Ltd | Balancing device |
| US9812866B2 (en) | 2015-02-19 | 2017-11-07 | Cummins Power Generation Ip, Inc. | Energy storage system |
| US9780567B2 (en) | 2015-02-19 | 2017-10-03 | Cummins Power Generation Ip, Inc. | Energy storage system |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4903184A (en) * | 1987-06-23 | 1990-02-20 | Kabushiki Kaisha Toshiba | Reactive power controller |
| DE19516604A1 (en) * | 1995-05-09 | 1997-02-13 | Siemens Ag | Method and device for the static and dynamic support of a mains voltage by means of a static compensation device with a self-commutated converter |
| DE19642596A1 (en) * | 1996-10-15 | 1998-04-23 | Siemens Ag | Method and device for compensating reactive current components by means of a compensation device with a pulse converter |
-
1997
- 1997-08-11 DE DE19734722A patent/DE19734722C2/en not_active Expired - Fee Related
-
1998
- 1998-07-27 DE DE59806638T patent/DE59806638D1/en not_active Expired - Fee Related
- 1998-07-27 AT AT98946245T patent/ATE229703T1/en not_active IP Right Cessation
- 1998-07-27 EP EP98946245A patent/EP1002353B1/en not_active Expired - Lifetime
- 1998-07-27 JP JP2000506705A patent/JP2001512956A/en not_active Withdrawn
- 1998-07-27 CA CA002300306A patent/CA2300306A1/en not_active Abandoned
- 1998-07-27 WO PCT/DE1998/002106 patent/WO1999008357A2/en active IP Right Grant
-
2000
- 2000-02-11 NO NO20000710A patent/NO20000710L/en not_active Application Discontinuation
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR3057405A1 (en) * | 2016-10-11 | 2018-04-13 | Institut National Polytechnique De Toulouse | METHOD FOR CONTROLLING PARALLEL ACTIVE FILTER FOR DISTURBED NETWORKS AND ASSOCIATED ACTIVE FILTER |
| WO2018069636A1 (en) * | 2016-10-11 | 2018-04-19 | Institut National Polytechnique De Toulouse | Method for controlling an active parallel filter for networks with interference and associated active filter |
| EP3813218A1 (en) | 2019-10-25 | 2021-04-28 | Wobben Properties GmbH | Arrangement for feeding electric power into an electricity supply network |
| US11573252B2 (en) | 2019-10-25 | 2023-02-07 | Wobben Properties Gmbh | Method for feeding electrical power into an electrical supply network |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2001512956A (en) | 2001-08-28 |
| DE19734722C2 (en) | 2000-06-08 |
| EP1002353A2 (en) | 2000-05-24 |
| ATE229703T1 (en) | 2002-12-15 |
| WO1999008357A3 (en) | 1999-04-15 |
| DE59806638D1 (en) | 2003-01-23 |
| WO1999008357A2 (en) | 1999-02-18 |
| NO20000710D0 (en) | 2000-02-11 |
| DE19734722A1 (en) | 1999-02-25 |
| NO20000710L (en) | 2000-02-11 |
| EP1002353B1 (en) | 2002-12-11 |
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