AU2008221581A1

AU2008221581A1 - Device for controlling an electric switchgear and related method

Info

Publication number: AU2008221581A1
Application number: AU2008221581A
Authority: AU
Inventors: Roberto Borlotti; Giuliano Corbetta
Original assignee: ABB T&D Technology AG
Current assignee: ABB Technology AG
Priority date: 1999-12-23
Filing date: 2008-09-19
Publication date: 2008-10-16
Also published as: AU2005200058A1

Description

00 oO a, Cu Oj

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant(s): ABB T D TECHNOLOGY LTD Invention Title: DEVICE FOR CONTROLLING AN ELECTRIC SWITCHGEAR AND RELATED

METHOD

The following statement is a full description of this invention, including the best method for performing it known to me/us: P46393AU.2 PatSetFilng Apphcaon 2008.9-18do (M) 00 DEVICE FOR CONTROLLING AN ELECTRIC SWITCHGEAR AND RELATED METHOD This patent application is a divisional application of Australian Patent Application 2005200058 and relates to subject matter disclosed but not claimed in that application.

Some description of the invention of Australian Patent Application 2005200058 is 00 included herein to facilitate understanding of the present invention. If necessary reference may be had to the disclosure of application 2005200058 to understand the Ci present invention, and the entire disclosure of that application is incorporated herein by 00 reference.

SDESCRIPTION

The present invention relates to a device for controlling the opening/closing operation of an electrical switchgear, such as a circuit breaker or a disconnector or a recloser or the like, and a control method related.

More specifically, the present invention relates to a device, which allows controlling the opening/closing operation of an electric switchgear, using a real time sensor-less control system.

Devices for controlling the opening/closing operation of an electric switchgear are well known in the start of the art.

An example of this kind of control devices, particularly useful for medium and high voltage applications for a voltage range higher than 1 KV), is disclosed in the European patent application N O 98204083.4, filed in the name of the same applicant, the description of which is to be understood as included herein, as reference.

In the mentioned patent application, it is disclosed a device for controlling the opening/closing operation of an electric switchgear, which is able to adjust in real time the control parameters in input to an actuator. In this way, it is possible to obtain a desired law of motion for movable parts of the electric switchgear, which the mentioned actuator operates.

In order to process the control signals necessary for achieving this aim, a control unit, which is included in the control device, is used. This control unit is needed to know in real time the position of the moveable parts of the electric switchgear. This is obtained, in the embodiments described in the mentioned patent application, using one or more feedback signal, which can provide the control unit with information, directly or indirectly related to the position of the movable parts of the electric switchgear.

00 This information can be provided in a direct manner, for example, with one or more feedback signals that can be sent by position and/or velocity and/or S acceleration sensors, suitably placed in predefined points of the kinematic chaifi, C) which connects the actuator to the movable parts of the switchgear. As it can be understood, this approach has the main drawback of requiring the __placement of dedicated sensors for generating feedback signals for providing the 00 control unit, in a direct or indirect manner, with information related to the N position of movable parts the switchgear.

00 Alternatively, this information can be provided, in an indirect manner, avoiding the use of position sensors. In fact, in this case, feedback signals, related the control parameters of the actuator, are generated by current/voltage sensors and subsequently sent to the control unit of the control device. In this way, the position of the movable parts can be calculated by the control unit. Also this solution, even if achieving the aims for which it has been conceived, has some drawbacks, such as the need of complex electronics (and related setting-up procedures) for generating the control signals necessary for adjusting in real time the control parameters in input to the actuator.

Therefore, the main aim of the present invention is to provide a device for controlling the opening/closing operation of an electric switchgear, which 2o represents a further technical improvement with respect of the state of the art, in particular with respect of the invention disclosed in the patent application mentioned above.

Within this aim, another object of the present invention is to provide a device for controlling the opening/closing operation of an electric switchgear, which allows avoiding the use of sensors for generating feedback signals for providing the control unit, in a direct or indirect manner, with information related to the position of movable parts the switchgear.

Another object of the present invention is to provide a device for controlling the opening/closing operation of an electric switchgear, which allows using a 2 00 relatively simple and low cost electronics for generating the control signals necessary for adjusting in real time the control parameters in input to the actuator.

Another object of the present invention is to provide a device for controlling the opening/closing operation of an electric switchgear, which allows using simple procedures for setting-up the electronics for generating the control signals 00 necessary for adjusting in real time the control parameters in input to the cN actuator.

N-

00 Another object of the present invention is to provide a device for controlling the D- opening/closing operation of an electric switchgear, which allows controlling the movable parts of the switchgear with an high level of reliability, improving the electric and mechanical life of the switchgear.

Not the least object of the present invention is to provide a device for controlling the opening/closing operation of an electric switchgear, which is of simple and relatively low cost realisation.

Thus, the present invention provides a device for controlling the opening/closing operation of an electric switchgear in a power distribution network, which comprises: a movable contact and a fixed contact that can be separated/coupled during the opening/closing operation of the switchgear; an electromagnetic actuator having a law of motion, which can be adjusted by a control unit, this electromagnetic actuator being operatively connected, by means of a kinematic chain, to the movable contact.

The device, according to the present invention, is characterised by the fact that the mentioned control unit comprises a first processing means for generating, based on predefined data, a first control signal, which is indicative of the actual law of motion of the movable contact operated by the electromagnetic actuator.

The device according to the present invention allows achieving the intended aims. In fact, the presence of the mentioned first processing means, which generate, based on predefined data, the first control signal, allows avoiding the 00 0 need of one or more feedback signals that directly or indirectly, provide information related to the position of the movable contact.

In practise, the first processing means generate the first control signal, which is 5 indicative of the actual law of motion of the movable contact operated by the electromagnetic actuator, basing uniquely on predefined data that are already available in the control unit.

In this way, it is possible to use relatively a simple, low cost and easily settable electronics for generating the control signals necessary for adjusting in real time 00 the control parameters in input to the actuator.

Further characteristics and advantages of the invention shall emerge more clearly from the description of preferred but not exclusive embodiments of the device, according to the present invention. The preferred embodiments of the device, according to the present invention, are illustrated purely by way of example and without limitation in the attached drawings, wherein: figure 1 is a diagram, which illustrates a schematic view of the device, according to the present invention; figure 2 is a diagram, which illustrates a schematic view of a detail of the device according to the present invention; !0 figure 3 is a diagram, which illustrates a schematic view of a possible succession of phases related to a control method that can be implemented in the device, according to the present invention.

Referring to figure 1, the device 1, according to the present invention, controls the opening/closing operation of an electric switchgear 2, in a power distribution network (not illustrated). The switchgear 2 comprises a movable contact and a fixed contact, globally indicated by reference 20, that can be separated/coupled during the opening/closing operation of the switchgear 2. The switchgear 2 comprises an electromagnetic actuator 21 having a law of motion, which can be adjusted by a control unit 10. The electromagnetic actuator 21 is operatively connected, by means of a kinematic chain 22, to the movable contact. The o electromagnetic actuator 21 comprises preferably an excitation circuit 23, for generating a magnetic flux and a movable element 24, operatively connected to the movable contact by means of the kinematic chain 22. The movable element 24 is operated by the magnetic force, which is generated by a portion of the magnetic flux, which is enchaned with the movable element 24.

0o The control unit 10 comprises a first processing means 11 for generating, based cl on predefined data (not shown), a first control signal 12, which is indicative of 00 the actual law of motion of the movable contact of the switchgear 2, which is 1, 3 operated by the electromagnetic actuator 21.

The control unit 10 comprises second processing means 13, which receive the first control signal 12 and generate a second control signal 14 for controlling (arrow 15) the flow of energy supplied to the actuator 21.

For reaching this aim, referring now also to figure 2, the control unit comprises converting means 100, which receive the second control signal 14 and modulate the flow of energy supplied to the actuator 21. The power supply means 100 comprise means 101 for supplying (arrow 15) power to the actuator 21 and means 102 for modulating the amount of power supplied, in relation to the second control signal 14. Advantageously, the power supply means 101 supply power to the excitation circuit 23 of the actuator 21.

Referring to figure 2, the first processing means 11 comprise estimating means 110 for determining, based on predefined data (not shown) related to the operating conditions of the electromagnetic actuator 21, the actual law of motion of the movable contact.

The mentioned predefined data are already available to the control unit and can be memorised using simple control procedures, that take into account the operating conditions of the actuator 21, that are known "per sC".

00 This fact facilitates the use of control digital techniques (for example by means of a microprocessor) for the generation of the first control signal 12 and/or the second control signal 14.

C) In order to storage the predefined data related to the operating conditions of the actuator 21, the estimating means 110 comprise first storage means 16, for memorising data that are related to the law of motion of the actuator 21.

00 Preferably, as it will described better hereinafter, this law of motion is expressed as a function of the portion of magnetic flux, which is enchaned with the 00 movable element of the electromagnetic actuator 21. Moreover, the estimating S0 means 110 can comprise second storage means 18 for memorising data (not shown) related to operating parameters of the electromagnetic actuator 21.

Preferably, in the second storage means 18, data related to the voltage and current applied to the excitation circuit 23 of the electromagnetic actuator 21 and data related to the working temperature of the actuator 21 are memorised.

In a preferred embodiment, for the sake of implementing a redundancy system, the actuator 21 can provide the control unit with a comparison signal (not illustrated), indicative of the value of magnetic flux, generated by the excitation circuit of the actuator 2 1. This can be easily obtained, without any complication of the control unit electronics, arranging, in a proper manner the excitation ,eo circuit 23.

The first processing means 11I comprise preferably means 111 for estimating the equivalent resistance of the excitation circuit 23 and means 112 for calibrating the estimating means 1 10 to the actual position of the movable contact of the actuator. The means 111 and 112 are particularly useful for ensuring a reliable control of the actuator 2 1.

The device according to the present invention allows the implementation of a control method 300, which is described hereinafter, referring to figure 3.

At it will appears evident hereinafter, the control method 300 allows appreciating the advantages of the device according to the present invention.

00 The control method 300 includes advantageously a succession of phases, which preferably comprises the phase a) (reference 301) of generating an operating commnand signal (reference 201 of figure 1) for the control unit 10. This C) operating command signal can be used for activating the control unit 10. Then, it can be provided the phase b) (reference 302) of generating, by means of the first processing means 11, the first control signal 12. As mentioned, the generation of 00 the control signal 12 is performed based on predefined data related to the operating conditions of the actuator 21.

00 Preferably the phase b) comprises the steps b. 1) of determining, by means of the 0) estimating means 110, the actual law of motion of the electromagnetic actuator 21 and the step b.2) of processing the first control signal, based on the step b. 1).

Preferably the step b. 1) comprises the sub-step i. of acquiring, from the first storage means 16, first predefined data (not shown) that are related to the law of motion of the electromagnetic actuator 21. These data are preferably expressed ias a function of the portion of the magnetic flux, which is enchaned with the movable element of the electromagnetic actuator 21. Accordingly, it can provided the sub-step ii. of acquiring, from the second storage means 18, second predefined data (not shown) that are related to the operating parameters of the electromagnetic actuator 2 1.

C- In a preferred embodiment the sub-step ii. comprises the sub-steps of: acquiring, from the second storage means 18, predefined data related to the voltage and current applied to the excitation circuit of the electromagnetic actuator 21; and acquiring, from the second storage means 18, predefined data related to the operating temperature of the electromagnetic actuator 21.

Then, it is preferably provided the sub-step iii. of determining the actual portion of magnetic flux, which is enchaned with the movable element of the electromagnetic actuator 21 and the sub-step iv. of estimating the equivalent resistance of the excitation circuit 23.

00 This estimation can be run in practice during the set-up procedures. It can be implemented, for example, injecting a step of current into the excitation circuit 23 of the actuator 21 and measuring the time constant of the response of the excitation circuit 23.

)Finally the sub-step v. of calculating the actual position of the movable element of the electromagnetic actuator 21 can be easily performed.

00 The phase b) and in particular the step b. 1) finds their foundation in the following theoretical considerations.

00 By means of a detailed analysis of the structure of the electromagnetic actuator 21, a function (DI which express the flux (D as a function of -the position x of the movable element of the actuator and of the current

T

c circulating in the excitation circuit of the actuator. So it can be written the following relation: The mentioned analysis can comprise preferably F.E. (Finite Element) modelling procedures while this relation can be memorised, for example in form of a table, in the first storage means 16. As mentioned, for the sake of redundancy, this table can be compared with a second table, in which the flux values can be provided by a comparison signal, sent by the actuator 21.

If also the voltage Vc and the equivalent resistance Rc of the excitation circuit 23 are known it can be written that: 0(0) J (Vc(y) Rc o Ic(y))dy 0 where is the initial value of the magnetic flux at the initial instant that can be acquired from the first storage means 16.

At this stage, combining the relations and the value of the position x(t) of the movable element of the actuator 21 can be calculated using the following relation: =D (OWQ, oo Once the position x(t) is known, it is easy to obtain the position x(t) of the S movable contact of the switchgear and accordingly generating the first control signal 14, which is indicative of the law of motion of the movable contact of the C) switchgear.

i For the practical implementation of this principle, it is necessary to take into account in the previous calculation the influence of the working temperature of 00 the actuator 21, which can be taken into account in the relation Moreover, in c- order to ensure a more reliable implementation of the theoretical relations above 00 illustrated, it can be provided the sub-step vi. of calibrating the estimating means 110 to the actual position of the movable element of the electromagnetic actuator 21.

Further it can be provided the phase c) (reference 303) of generating, by means of the second processing means 13, the second control signal 14. The generation of the second control signal 14 allows performing the subsequent phase d) (reference 304) of modulating, by means of the converting means 100, the flow of energy supplied to the electromagnetic actuator 21. So, it can be adjusted the force, which the electromagnetic actuator 21 exerts on the kinematic chain 22, in order to obtain a desired law of motion for the movable contact.

In a preferred embodiment of the control method 300, the phase c) comprises the yu steps c.1) of comparing the first control signal 12 with one or more reference signals (not illustrated). The mentioned reference signals are indicative of a predetermined law of motion of the movable contact operated by the electromagnetic actuator 21. Then, the step c.2) of processing the second control signal 14, based on the step may be provided. In practice, a closed loop control scheme can be used for generating the second control signal 14.

It has been proven in practice that the device for controlling the opening/closing operation of an electric switchgear allows achieving the intended aims.

In particular a simple and reliable electronics can be used in the control unit This can be obtained thanks to the presence of the first processing means 11 that

I

allow to generate the first control signal 12 basing on data that are substantially oO O already available to the control unit 10. In this manner, it can be avoided the need of reporting feedback signals, expecially using external sensors. As described above, it has been made possible to implement simple control procedures, that are particularly suitable for the implementation by means of a microcontroller, oo The device according to the present invention is susceptible of numerous Smodifications and variations, all of which are within the scope of the inventive oo concept. All the details may furthermore be replaced with other technically 0 equivalent elements.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims

2. A device according to claim 1, characterised by the fact that said electromagnetic actuator (21) comprises: an excitation circuit (23) for generating a magnetic flux; and a movable element (24) operatively connected to said movable contact by means of said kinematic chain said movable element (24) being operated by the magnetic force which is generated by a portion of said magnetic flux which is enchained with said movable element (24). o
3. A device according to claims 1 or 2, characterised by the fact that said Sfirst processing means (11) comprise means (111) for estimating the equivalent resistance of the excitation circuit (23) of said electromagnetic r. actuator (21). s 4. A device according to one or more of previous claims, characterised by the fact that said first processing means (11) comprise means (112) for 0 calibrating to the actual position of the movable element (24) of said electromagnetic actuator (21). 0o
5. A device according to one or more of previous claims, characterised by the fact that said control unit (10) comprises second processing means (13) which receive said first control signal (12) and generates a second control signal (14) for controlling the flow of energy supplied to said actuator (21).
6. A device according to one or more of previous claims, characterised by the fact of comprising converting means (100) which receive said second control signal (14) and modulates the flow of energy supplied to said actuator (21).
7. A device according to claim 6, characterised by the fact that said converting means (100) comprise power supply means (101) for supplying power to said actuator (21) and means (102) for modulating the amount of power supplied by said power supply means (101) to said actuator (21) in relation to said second control signal (14).
8. A device according to claim 7, characterised by the fact that said power supply means (101) supply current to the excitation circuit (23) of said actuator (21).
9. An electric switchgear characterised by the fact of comprising a device (1) for controlling the opening/closing operation of said electric switchgear (2) according to one or more of previous claims. 00 10. A control method (300) for controlling the opening/closing operation of al electric switchgear (2 1) according to claim 11, characterised by the fact of comprising the following phases: generating an. operating command signal (20 1) for said control unit generating, based on Predefined data, by means of said first processing means a first control signal (12) which is indicative of actual law cof 00 motion of said movable contact (20) operated by said electromagnetic actuator (21); 00 based on said first control signal generating, by means of said secoaid processing means a second control signal (14) for controlling the flow of energy supplied to said electromagnetic actuator (21); based on said second control signal modulating, by means of said converting means (100), the flow of energy supplied to said electromagnetic actuator so as to adjust the force which said electromagnetic actuator (21) exerts on said inemnatic chain in order to obtain a desired law of motion for said movable contact
11. A control method (300) according to claim 10, characterised by the fact that said phase b) comprises the steps of. b. 1) determining, by means of said first processing means the actual law of motion of said electromagnetic actuator and b.2) based on said step processing said first control signal (12).
12. A control method (300) according to claim 9, characterised by the fact that said step b.1) comprises the sub-steps of: acquiring, from said first storage means first predefined data that are related to the law of motion of said electromagnetic actuator said data being expressed as a function of the portion of the magnetic flux which is enchained with said movable element (24) of said electromagnetic actuator (2 and 13 acquiring, from said second storage means second predefined dat 00that are related to the operating parameters of saidectoaei auar c-i and -determining the actual portion of magnetic flux which is enchained wilth C* 5 the movable element (24) of said electro magnetic actuator and -estimating the equivalent resistance of the excitation circuit (23) of said 0C) electromagnetic actuator and calculating the actual position of said movable element of said CI electromagnetic actuator (21). 0io
131. A control method (300) according to claim 12, charactensdb h atta 0 iedb hefctta said step b. 1) comprises the sub-steps of: -calibrating said estimating means (1 10) to the actual position of the movable element (24) of said electromagnetic actuator (21). 14. A control method (300) according to claim 10 or 11, characterised by the fact that said sub-step ii. comprises the following sub-steps: acquiring, from said second storage means predefined data related to the voltage and current applied to the excitation circuit (23) of said electromagnetic actuator and acquiring, from said second storage means predefined data related to the operating temperature of said electromagnetic actuator (21). A control method (300) according to one or more of claims from 12 to 16, characterised by the fact that said phase c) comprises the steps of: c.1) comparing said first control signal (12) with one or more reference signals which are indicative of a predetermined law of motion of said movable contact (20) operated by said electromagnetic actuator and c.2) based on said step c.l1), processing said second control signal (14).