Description:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to the distribution transformer and more particularly, to the automation of on-load LT isolation mechanism in Distribution Transformer.

BACKGROUND OF THE INVENTION
Generally, the distribution network consists of a large number of DTRs and LT pillar boxes distributed across a wide range of areas. Whenever, there are reports of water logging in the area, in the vicinity of the LT pillar box fed by a particular DTR, LT personnel need to move to that area to manually switch OFF the conventional CFS of the source DTR to de-energize the power of the LT pillar box as many of these pillar boxes are prone to inundation due to water-logging. Once waterlogging occurs it becomes an arduous task to cut off the supply locally. This process is not only time-consuming, increasing the risk of electrocution during that time, but it also becomes an impossible and risky activity to access that waterlogged DTR or LT pillar box.

In the existing art, the only viable action was to switch OFF the upstream HT feeder supplying power to that affected DTR and few more DTRs in chain from the source distribution station. This results in unnecessary outage of supply to vast areas which may not be water logged. In other words, the source HT feeder supplying power to the inundated LT pillar box needs to be switched OFF from the Distribution Substation causing widespread outage.

To avoid this situation, it is a necessity to remotely operate the source DTR CFS unit of the inundated LT pillar box, once the information of waterlogging is received and also monitor the necessary electrical and mechanical parameters before and after operation to detect any abnormalities.

Hence there is a need for the introduction of a new system that aims to overcome these drawbacks and provide a more efficient solution. This patent application proposes novel features distinct from the existing prior art, providing ground-breaking advancements and unique solutions that significantly enhance functionality and efficiency in the relevant field of technology.

SUMMARY OF THE INVENTION
The following disclosure presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

An object of the present invention is to provide a novel system to overcome the drawbacks of the prior art.

Another object of the present invention is to ensure prompt isolation of the LT network remotely in the area where waterlogging has occurred.

Another object of the present invention is to provide a system that serves a dual purpose in not only ensuring the safety of humans from electrocution in waterlogged areas but also minimizing the area of outage which would have been caused due to switching ‘OFF’ the HT feeder supplying the source DTR from Substation.

One aspect of the present disclosure is to provide a system to prevent electrocution resulting from inundated live parts of the LT Pillar Boxes (Distribution boxes) in waterlogged areas during rainy season. For this, an IIoT based system is designed, developed and implemented to quickly switch OFF the innovatively designed motorized retrofitted CFS of the DTR remotely to de-energize the LT pillar box, prior to water logging condition. This is an innovative operational approach and first of its kind in the LT network and DTRs located at the road-side of the city. By achieving monitoring and control of the CFS unit of the DTR it is possible to isolate the LT side of the DTR or in other words switch ‘ON’ or ‘OFF’ from remote without physically going to the DTR. Thus, any kind of activity where an isolation is required in the LT CFS unit of the DTR can be remotely controlled and monitored saving time and operating personnel involvement.

In one implementation of the present invention, a system is provided for achieving automation of on-load Low Tension (LT) isolation in Distribution Transformer. The system comprises:
mechanical assembly;
control circuit;
IIoT gateway;
wherein IIoT gateways are microcontroller-based devices;
wherein the mechanical assembly comprises a combined fuse switch (CFS) unit and gear assembly.

The advantages of this system are public and operating personnel safety, prevention of unnecessary widespread outage of supply, pilferage control, elimination of manpower requirement for CFS operation.

Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The above and other aspects, features and advantages of the embodiments of the present disclosure will be more apparent in the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 illustrates LT Combined Fuse and Switch (CFS) Automation Architecture according to one implementation of the present invention.

Figure 2 illustrates the block diagram of the CFS operating system according to one implementation of the present invention.

Figure 3 illustrates the gear arrangement according to one implementation of the present invention.

Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may not have been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure.

DETAILED DESCRIPTION OF THE PRESENT INVENTION
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding, but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments belong. Further, the meaning of terms or words used in the specification and the claims should not be limited to the literal or commonly employed sense but should be construed in accordance with the spirit of the disclosure to most properly describe the present disclosure.

The terminology used herein is for the purpose of describing particular various embodiments only and is not intended to be limiting of various embodiments. As used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising" used herein specify the presence of stated features, integers, steps, operations, members, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, members, components, and/or groups thereof.

The present disclosure will now be described more fully with reference to the accompanying drawings, in which various embodiments of the present disclosure are shown.

A distribution network consists of a large number of DTRs and LT pillar boxes distributed across a wide area. Many of these pillar boxes are prone to inundation due to water-logging in the adjoining areas. Once waterlogging occurs it becomes an arduous task to cut off the supply locally. Thus, as mentioned earlier the source HT feeder supplying power to the inundated LT pillar box is switched OFF from the Distribution Substation causing widespread outage.

To avoid this situation, it is a necessity to remotely operate the source DTR CFS unit of the inundated LT pillar box, once the information of waterlogging is received and also monitor the necessary electrical and mechanical parameters before and after operation to detect any abnormalities.

In one implementation of the present invention, a system is provided for achieving automation of on-load Low Tension (LT) isolation in Distribution Transformer. The system comprises: mechanical assembly, control circuit, IIoT gateway. The IIoT gateways are microcontroller-based devices and the mechanical assembly comprises a combined fuse switch (CFS) unit and gear assembly.

A smart kiosk is designed to house all the components required for achieving automation or remote monitoring and control of the CFS unit. The smart KIOSK in Fig 1 broadly consists of the mechanical assembly, the control circuit and the IOT gateway.

MECHANICAL ASSEMBLY
The Electro-Mechanical driving gear arrangement is CFS (Combined Fuse Switch) Unit agnostic; the arrangement can be used with any type of fuse switch unit of any available rating. The gear arrangement is indirectly coupled with the CFS driving shaft instead of direct coupling as shown in Fig. 2, so no extra spring is required with the drive mechanism for quick operation, rather the mechanism is capable of using the inbuilt spring of the switch / CFS. This system is unique because it is not an integral part of any specific CFS (Combined Fuse-Switch Unit) type equipment; rather can be used for any kind of CFS type of switches for electrical automation from remote.

Gear Assembly of Fig. 3 was designed for speed reduction and a special Gear Arrangement was also developed for free rotation after ON / OFF operation of CFS to optimize mechanical thrust. Also, the same gear arrangement is helpful for integration with any type of CFS driving shaft. The coupling arrangement is of detachable type with safe isolation position locking to enable manual operation as a fallback to electro mechanical system failure. CFS ON / OFF condition is always indicated locally or from remote, irrespective of electro-mechanical system (Motor-Gear Assembly) either in engaged or in dis-engaged condition.

CONTROL CIRCUIT
The control circuit serves the purpose of handshaking between the mechanical assembly and the signals received from remote control room for operation of the CFS unit. The control circuit receives the three-phase top voltage from the CFS unit after which a phase selection is carried out by one out-of- three logic using a phase selector for conversion to single phase voltage and also ensure redundancy of input supply in case of absence of voltage on any of the phases.

2-stage operational safety control of CFS has been implemented to prevent the spurious operation of the LT CFS. In the first stage the motor control supply is activated for a limited time duration (with the help of timer) and thereafter, in the second stage the remote command is executed only if given within that specific time duration. To achieve this, three AC contactors have been used, of which one is for ON operation, another for OFF operation and the third is used for feeding the AC single phase voltage from phase selector to the rectifier unit whenever any command is given from remote. The rectifier unit DC output voltage is finally fed to the motor input terminals.

Now the direction of rotation of the motor or in other terms switching OFF or ON of the CFS unit is dependent on the DC rectified voltage polarities at the motor terminals which are interchangeable depending on the status of the ON and OFF contactors.

The microcontroller cum IIoT gateway receives various field information in the form of analogue and digital inputs. These include
i) Status of CFS unit and its components (such as MCBs, ON /OFF position limit switch, motor DC supply etc)
ii) CFS unit top and bottom voltages
iii) Local /remote switch status
iv) Rectifier AC supply voltage from phase selector

IIoT GATEWAY
IIoT Gateways are microcontroller-based devices, which on one side is integrated with the Control Circuit to acquire digital and analogue signals through its I/O ports and on the other side it has a built-in cellular communication module to handle data exchange with the HES via Broker. The devices are capable of handling multiple input and outputs and is powered up through Auxiliary power supply.

Low processing power and usage of lightweight protocol like MQTTs for exchange of data with Broker (is a software which facilitates message transfer between Communication Gateways and HES) over cellular network using Publish /Subscribe model makes these devices perfect for field level implementation.

In MQTTs the message transport is done by publishing a message to the Broker on a specific subject called Topic. Thereafter to receive a published message from the Broker, the receiver needs to subscribe to that specific topic of interest at the Broker. For message exchange, both the IIoT Gateway and HES need to connect to the same Broker. This is industry standard protocol for IIoT communications.

The HES comprises of a SCADA software application which utilises this information to display real-time parameters in the Client Workstation and stores this data along-with Event Logs in DB for future analysis. Furthermore, the interactive dashboard not-only enables remote monitoring but also provides remote operation facility to the client as and when required.

The concept of integrating physical machinery with networked sensors and interactive software to gather and analyse data in real-time, and perform remote operation based on requirements is the key working principle of the project which has not only helped to optimise operations but has also increased productivity with reduced downtime.

KEY CONSIDERATIONS:
• Instead of implementing conventional MQTT based solutions over internet and public infra, we have considered a more secure platform for data exchange, not only between the end device and the broker but also from the HES to the client location.
• MPLS based 4G Pvt APN have been configured over the Mobile Service Providers Network solely for this requirement and has been deployed in hub-spoke configuration.
• MQTTs protocol with TLS/SSL secure channel have been used for encrypted payload transfer over the most commonly used MQTT protocol which runs on top of basic TCP/IP protocol stack.
• Instead of shared public infra for broker, private broker has been considered and hosted inhouse to enhance security measures.
• Two-stage firewall have been considered, wherein a Next gen Firewall with IOT filtering have been placed strategically at the perimeter and the secondary firewall have been placed between the core infra and the clients to secure threats arising from Users.

STAGE OF DEVELOPMENT
The project is a first of its kind initiative to introduce automation in the existing CFS unit of DTRs located at various areas of the distribution system. This has been achieved by retrofitting of existing CFS unit by a modified assembly wherein the CFS operation, which was earlier done manually by human personnel locally, can now be operated electrically both from local or remote. Thus, multiple iterations of the mechanical assembly along with the control system and associated communication platform had to be carried out to design a prototype for initial testing.

The prototype was developed in various stages:

1. DESIGN AND DEVELOPMENT

i) Mechanical assembly with motor-gear arrangement which was to be fitted with the existing CFS unit of DTRs.
ii) Robust control system for fail-safe operation of the CFS unit along with proper interlocking logic to prevent any kind of unwanted operation.
iii) Communication architecture for secure and reliable handshaking between the field device and remote server or HES including implementation of a lightweight yet secure protocol
iv) Development of one prototype based on the finalized design.

2. OPERATION CHECK

i) Prototype installed at one spare DTR and operation of the CFS unit was checked from both local and remote.
ii) Minor improvements carried out in design based on results obtained

3. COMMISSIONING

i) After successful trial of prototype, implementation carried out in 24 DTRs as part of PHASE-I and PHASE-2 commissioning.

NOVEL FEATURES:
This innovation has got some specific novel features: -
• In a first-of-its-kind initiative, automation has been introduced in the existing CFS unit of distribution transformers.
• The system is capable of monitoring and controlling the existing CFS unit, located on the LT side of DTRs, from a remote-control center.
• It is a completely innovative and in-house developed solution where additional innovative mechanical arrangement has been integrated with the existing CFS unit, while maintaining its basic mechanism, to enable remote control and monitoring of the CFS unit.
• The additional mechanical arrangement for CFS operation is vendor-agnostic, capable of operating smoothly with any make, type, and rating of CFS.
• All components, including the control circuitry, have been locally sourced, ultimately reducing the implementation cost of the project.
• The mechanical assembly features a simple yet robust design that ensures reliability and facilitates troubleshooting in case of any issues.
• The IIoT-based system is built on a lightweight yet secure MQTT backbone, enabling seamless transfer of data or commands between field devices and the remote HES, or vice versa.
• To ensure fail-safe and cybersecure operation, a two-stage operational control has been incorporated.
• Additionally, logic driven safety interlocks are in place to eliminate operational errors.

BEST MODE OF WORKING THE INVENTION:
The system may be deployed in any LT side of DTR where CFS unit is present and isolation (switching ON and OFF) of this unit is done manually. The existing CFS unit may be retrofitted with the electromechanical drive- gear assembly along with the associated control circuit and the communication equipment to achieve the desired outcome.

This in-house developed technology solution is used in the DTRs of the utility distribution network, for operating conventional CFS with retrofitted Motorized Mechanism, using an IIoT based system, locally as well as from Remote.

Those skilled in the art will recognize other use cases, improvements, and modification to the embodiments of the present disclosure. All such improvements and other use-cases are considered within the scope of the concepts disclosed herein.

SEARCH TERMS/LIST OF SYNONYMS
Some of the abbreviations used in this disclosure form have been described as follows: -
CFS: Combined Fuse and Switch. This is a part of Distribution Transformer, used to disconnect the LT line from Distribution Transformers
DTR: Distribution Transformer
LT: Low Tension
Smart Kiosk: A local enclosure fitted with the distribution transformer comprising of mechanical assembly, electronic and communication equipment responsible for remote electrical operation of CFS
Gateway Module: Local communication equipment responsible for remote monitoring and control of CFS
IT: Information Technology
OT: Operational Technology. This is focused on field level operation of DTR by remote command.
IIoT: Industrial Internet of Things
Firewall: Network security device that monitors incoming and outgoing network traffic from/to IT and OT network.
MQTTs: Secure Message Queuing Telemetry Transport for IIoT based protocol implementation
HES: Head-End System -remote user interface for Control and Monitoring of CFS operation from remote
, Claims:
1. A system for achieving automation of on-load Low Tension (LT) isolation in Distribution Transformer, comprising:
mechanical assembly;
control circuit;
IIoT gateway;
wherein IIoT gateways are microcontroller-based devices;
wherein the mechanical assembly comprises a combined fuse switch (CFS) unit and gear assembly.

2. The system as claimed in claim 1, wherein the CFS unit is used to disconnect the LT line from Distribution Transformers.

3. The system as claimed in claim 2, wherein the gear assembly is indirectly coupled with a CFS driving shaft instead of direct coupling.

4. The system as claimed in claim 1, wherein the control circuit serves the purpose of handshaking between the mechanical assembly and the signals received from remote control room for operation of the CFS unit.

5. The system as claimed in claim 1, wherein the microcontroller based IIoT gateway receives various field information in the form of analogue and digital inputs.

6. The system as claimed in claim 1, wherein IIoT gateway has a built-in cellular communication module to handle data exchange with a Head-End System (HES).

7. The system as claimed in claim 1, wherein IIoT gateway devices are capable of handling multiple inputs andand outputs and is powered up through Auxiliary power supply.

8. The system as claimed in claim 6, wherein the HES comprises of a SCADA software application that utilizes information to display real-time parameters in the Client Workstation and stores this data along-with Event Logs in DB for future analysis.

9. The system as claimed in claim 1, wherein MQTTs protocol with TLS/SSL secure channel is used for encrypted payload transfer over the most commonly used MQTT protocol which runs on top of basic TCP/IP protocol stack

10. The system as claimed in claim 6adapted to monitor and control the existing CFS unit, located on the LT side of Distribution Transformer, from a remote-control center.