AU756848B2

AU756848B2 - Oscillating circuit assembly for a centralised telecontrol audio frequency for a multiphase supply grid

Info

Publication number: AU756848B2
Application number: AU59836/00A
Authority: AU
Inventors: Jean Richa
Original assignee: Siemens Metering AG
Current assignee: Siemens Schweiz AG
Priority date: 1999-07-29
Filing date: 2000-07-10
Publication date: 2003-01-23
Anticipated expiration: 2020-07-10
Also published as: WO2001010055A1; DE50014746D1; DE19935381A1; ATE377296T1; EP1198898B1; EP1198898A1; HRP20020082A2; HUP0201983A2; HU224508B1; HUP0201983A3; NZ516697A; CZ2002335A3; AU5983600A; YU4102A

Abstract

The aim of the invention is to enable a space-saving exterior installation of an oscillating circuit assembly (1) for a centralised telecontrol audio frequency in an electric energy supply grid (6). To this end, a mutual magnetic influence of the coils (L1, L2, L3) is taken into consideration when they are proportioned, in order to achieve a compensation. Line reactors (LD1, LD2, LD3) can also be optionally mounted in series with the coils (L1, L2, L3).

Description

Description Resonant circuit arrangement for ripple-control audio frequency for a multi-phase supply network.

In electric energy supply networks, in particular high voltage networks, to which power plants with generators are connected, the short-circuit currents existing are often very high because of the resulting very low network impedances. Reactors are therefore used to limit the 50Hz short-circuit currents. Such a reactor is also described as a current-limiting reactor or short-circuit current limiting reactor (in the following C description configured and described as an air-cored reactor).

These limiting measures act upon the audio frequency of ripple control systems that are superposed on the 50Hz network. In order to prevent reduction of the audio frequency signals, audio frequency anti-resonance circuits are used that are tuned to the corresponding audio frequencies. For example, a series connection with a limiting reactor and a parallel resonant circuit configured as an anti-resonance circuit for the o Is audio frequency signal can be connected between a generator and a supply network.

"It is known in practice to accommodate the inductive elements, namely the limiting reactor and the coil of the parallel resonant circuit, in a common oil-immersed transformer housing. The inductive elements are then configured as iron coils with a core. Because of the relatively large amount of oil in the transformer housing, strict measures have to be put in place with respect to pollution and fire. Because of the iron core, when there are high currents when a short-circuit occurs it is also extremely difficult to maintain the required linearity of the resulting impedances. As a rule, thus, P a solid iron core is necessary, whereby however, the power loss increases in normal operation. A configuration of the inductive elements in a common housing or as a common component is known from DE 195 10 659 C 1.

Furthermore, there is known from the article "A COST-INTERFERENCEIVE

PI

NETWORK FOR ELIMINATION OF STIFF TRANSMISSION CROSSTALK IN ZERO SEQUENCE PROPAGATED DISTRIBUTION POWER LINE CARRIER i- SIGNALS" by K.W. Whang, IEEE Transactions on Power Delivery, US, IEEE Inc.

r4// New York, Bd PWRD-2, No. 1, pages 41-49, XP002033031, a resonant circuit arrangement for ripple control audio frequency for a multi-phase supply network, wherein for each phase of the supply network there is a resonant circuit with a capacitor and a coil, wherein the coils of the resonant circuit of the respective phases are placed in spatial proximity to one another such that a mutual inductive interference occurs.

The object of the invention is to provide a resonant circuit arrangement that allows a space-saving arrangement in the case of outdoor installation.

lo The solution of the object is provided in accordance with the invention by the features of claim 1. Accordingly, a resonant circuit arrangement for ripple control audio frequency for a multi-phase supply network is provided, wherein the resonant circuit arrangement has a resonant circuit with a capacitor and a coil for each phase. The coils of the respective phases are configured in spatial proximity to one another such that a mutual Is inductive interference occurs. The respective coils are rated with respect to a predetermined impedance of the respective filters such that the mutual interference is compensated for with respect to the impedance.

S In this way it is possible to have a space-saving arrangement of the respective resonant circuits, wherein they can possibly fall short of the so-called "safe-clearance or tier spacing" necessary according to VDE 0101/47. With configuration of such resonant circuits in outdoor installations without mutual interference, spacing of up to more than m would possibly be necessary. Hereinafter, the respective coils will be rated such that the mutual interference is compensated for, wherein at the same time adjustment of the 25 respective performances of the coils occurs. In principle, it is also conceivable to obtain o mutual interference by adjusting the respective capacitors. In this way, however, the different performances of the coils are not taken into account, wherein yet again optimum matching is not ensured.

The coils are preferably configured as air-cored reactors in a dry-type configuration. In this way, inexpensive manufacturing, avoiding the disadvantages described hereinabove in the prior art, is possible.

[I:\DAYLIB\LIBE]03757.doc:edg The respective coils are preferably installed in series, that is to say side-by-side mounting, wherein the installation direction is at right-angles to the direction of energy flow in a switchgear panel provided. In this way a space-saving and symmetrical installation is possible in the switchgear panel.

In a further advantageous embodiment, reactor coils for the electrical energy are comnnected in series with the respective coils, wherein the limiting reactors are optionally also arranged in spatial proximity to the coils. In this way a compact arrangement and combination of resonant circuit and current limiting is possible.

C' Advantageously, the coils can be provided at their end with fine pick-ups that allow 1o fine-tuning of the respective inductance by up to In this way fine-tuning is additionally made possible when the installation is set up.

Further advantages and details of the invention will be explained hereinafter in more detail with reference to an embodiment. There is shown, in: Fig. 1 an electrical diagram or a three-phase resonant circuit arrangement, Figs. 2 and 3 a switchgear panel with a resonant circuit arrangement in a plan view and respectively a side view, and Fig. 4 characteristic curves of a resonant circuit arrangement.

In the Figures described hereinafter, like details are provided with like reference signs.

Fig. 1 shows an electrical diagram of a resonant circuit arrangement 1, which is connected to an electrical energy supply network 6. Electrical energy is supplied in a three-phase manner from a generator 3 to the resonant circuit arrangement 1, and from there further conducted via outgoing circuits 5 to an electrical energy supply network 6. By way of an example, the arrangement shown can be configured for 120 kV or generally for high or medium-high voltage.

The resonant circuit arrangement 1 is provided, for each phase P1, P2 and P3, with an inductance LI, L2, L3 with a parallel capacitor C1, C2, C3, whereby for each phase a Sresonant circuit S 1, S2 and respectively S3, in particular an anti-resonance circuit, is formed. The stop frequency of these resonant circuits S 1 to S3 is rated for the respectively selected ripple control frequency. This can be between approximately 100 and 1000 Hz. Preferred ripple control frequencies are, for example, 183.6, 283.6 or 425 Hz. A special, or preferred ripple control frequency is 216 2/3 Hz.

In order to limit the short-circuit currents between the generator 3 and the outgoing circuits 5, which, for example, can also be achieved through technical measures at the generator 3 or at the energy supply network 6, in this case each phase P1, P2, P3 is provided with an air-cored reactor LD 1, LD2 and LD3 as a short-circuit current limiting reactor.

to All the inductive components, in particular the coils L1, L2 and L3 and possibly the air-cored reactor LD3 are arranged in spatial proximity to one another such that they mutually interfere with one another. This can be in spatial proximity, for example, such that they can possibly fall short of the voltage spacings required by the standard described hereinabove. In this way mutual inductive interference occurs between the inductive components that results in a change in the respective resonant circuits. In this case, the aim is to compensate for this interference while retaining the spatial ~proximity.

To this end, at least the respective coils L1, L2, L3 are rated such that the mutual interference is taken into account. This relates in particular to the centre coil L2, that is 20 surrounded by the other coils L1 and L3. Only by taking into account these interferences and adjusting the respective inductances, in particular by adjusting the respective number of turns per unit length, is optimum rating of the respective resonant circuits S 1, S2 or S3, or filters, possible. This is particularly relevant when the performances of the respective coils L1 to L3 are to be retained. This also does change in the case of mutual interference.

9. 99 A resonant circuit of this type, configured as a stop filter, can have, for example for 120 kV, reverse d.c. resistance or reverse impedance of approximately 300 Ohm at 216.6 Hz. The values for the coil L1 and the capacitor C1 are 2.86 mH and 188.6gF 2 respectively. The value for an air-cored reactor according to the example shown can ,be, for example, 25 mH.

Figs. 2 and 3 show an installation of the resonant circuit arrangement 1 in plan view and respectively in a side view. By way of an example, the arrangement 1 will hereinafter described in more detail with reference to a phase P3. The description is analogous for all the phases.

Figs. 2 and 3 show a configuration as an outdoor installation. In this case the energy is supplied by the generator 3, which is not shown in more detail, to the switchgear panel 7 upon which the resonant circuit arrangement 1 is installed. The electrical energy is supplied by means' of lines, not described in further detail, via a first isolating switch 9a, to the resonant circuit arrangement 1. A second isolating switch 9b is provided on So the outgoing side on the switch panel 7. The isolating switches 9a and 9b serve for disconnection of the resonant circuit arrangement 1. This can be necessary, for example, for servicing works or for other situations during operation.

Further along the line, for phase P3, there is the coil L3 that is connected parallel to the capacitor C3. Furthermore, the air-cored reactor LD3 is connected in series. The coils 15 L1 to L3 are preferably installed in series with respect to one another, as shown, wherein this side-by-side arrangement is at right-angles to the direction of energy flow in the switchgear panel 7. The air-cored reactors LD1 to LD3 are installed in a S"triangle. Because of their intrinsic size, larger spacing is possibly necessary than with the coils L1 to L3. In principle, this is also the case with the capacitors C1 to C3.

K. 20 In principle, it is conceivable that other installations are possible, for example a triangular configuration of the coils L1 to L3, with mixed airangement of the respective other components, or possibly also an inclined or diagonally staggered arrangement of the coils. In particular, asymmetrical arrangement of the respective ,components is also possible, whereby a further optimum installation in spatial S°oo proximity to one another can be possible.

As can be seen in particular from the side view according to Fig. 3, the connecting lines, not described in further detail, between the respective components are possibly conducted over pin insulators 1 1 for additional support. With respect to the necessary safety clearances, all the components and the pin insulators 11 are configured on 3 30z, supporting structures 13, so that the necessary clearances are provided with respect to the base.

It is significant in the configuration shown that all the inductive parts are configurel in dry-type configuration, and are arranged in spatial proximity to one another on the switchgear panel 7. When rating the coils L1 to L3, in particular the magnetic coupling between the coils L1 to L3 dependent upon their geometric configuration is taken into consideration. This also possibly concerns interference of the air-cored reactors LD1 to LD3. According to this configuration and the resulting calculation data, the total number of turns of each individual coil or reactor is calculated and matched in the practical configuration.

1o As this calculation possibly cannot take into consideration all the interferences, each coil L1 to L3 can additionally be provided on its end with a fine pick-up for finetuning. This can be configured, for example, as a pick-up for the respective turns, which are accessible via appropriate clamps or picking-up means. In this way, it is also possible to compensate for changes in inductance at full or weak loading. In this mamnner changes, by redesigning the arrangement, for example when renovations are o made; can be taken into account later.

In the embodiment shown, in particular the interference of the air-cored reactor LD2 upon the resonant circuits S1 to S3 has to be taken into account. In particular, the centre resonant circuit S2 experiences the greatest interference because of the inductances surrounding it. In Fig. 2, the spaces Al and A2 are shown in order to make clear the relative dimensions. In practice, for the embodiment shown, these are approximately 3 m and respectively 5.42 m. Using the component values described gohereinabove, tests showed that by means of the side-by-side mounting of the coils L to L3 shown, for the centre coil L2 there was a change of-0.078 mH, and for the two outer coils L 1 and L3 a change of +0.016 mH, compared to their nominal values.

~These interactions are now taken into account in rating the coils, so that the filter or resonant circuit frequencies are optimised.

Fig. 4 shows a diagram in which, by way of an example, the impedance is shown dependent upon the frequency for a parallel resonant circuit and from which the mutual 36-3 interference of the coils can be recognised. In a test, the spacing of the coils of the 097 respective phases with respect to one another was altered. The two impedance curves KI and K2 were established. The curve K1 has its peak at approximately 216 Hz. By means of the inductive interference of the coils with one another, a change of approximately 0.6 Hz occurs, corresponding to 216.06 Hz. In relation to the 216.06 Hz, this is a change to the impedance of approximately 170 Ohm, which is possibly in the region of half the reverse resistance of such an arrangement. If the mutual interferences are not taken into account, the performance of the coils possibly also remains not accounted for, whereby increased losses have to be borne again.

The basic concept of the novel idea can also be described in the following way: for io rating the resonant circuit, the coupling between the individual coils or inductances is calculated dependent upon their geometrical configuration. According to the calculation data, the number of turns per unit length of each coil is calculated individually. For fine-tuning of the system during installation, additional turns and fine-tuning pick-ups are provided. In this way, compensation for changes in inductance both for capacity loading and for weak loading is possible for the entire resonant circuit arrangement.

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Claims

1. Reasonant circuit arrangement for ripple control audio frequency for a multi- phase supply network, wherein for each phase (P1 to P3) of the supply network there is arranged a resonant circuit comprising a capacitor (Cl to C3) and a coil (L1 to L3), 0o wherein the coils (LI to L3) of the respective phases (P1 to P3) are configured in spatial proximity to one another such that mutual inductive interference occurs, 0 :charaterised in the coils (L1 to L3) of the respective phases (P1 to P3) 15 are assessed with respect to a pre-determined impedance of each of the respective resonant circuits for each phase (P1 to P3) such that the mutual inductive interference is compensated for dependent upon the geometrical configuration of the coils (L1 to L3) with respect to one another by adjusting the number of turns of the coils (L1 to L3).

2. Resonant circuit arrangement according to claim 1, wherein the coils (L1 to L3) are configured as air-cored coils. *g

3. Resonant circuit arrangement according to claim 1 or 2, wherein the coils (L1 to L3) are mounted side-by-side.

4. Resonant circuit arrangement according to claim 3, wherein the side-by-side mounting of the coils (L1 to L3) is arranged in a switchgear panel and the installation direction of the side-by-side mounting is at right-angles to the direction of flow of electrical energy in the switchgear panel.

Resonant circuit arrangement according to claims 1 to 4, wherein the respective R resonant circuits (S1 to S3) of the respective phases (P1 to P3) are configured as series or parallel resonant circuits. [R:\LIBE]03886.doc:edg -9-

6. Resonant circuit arrangement according to a claim 5, wherein when configured as a parallel resonant circuit, the resonant circuits (Si to S3) are each connected in series to a respective air-cored reactor (LD1 to LD3) for limiting current. DATED this fifth Day of June, 2002 Siemens Metering AG Patent Attorneys for the Applicant SPRUSON FERGUSON *o S S oooo [I:\DAYLIB\L1BEjo3757.doc:edg