It is accepted that industrial activity and the power sector are closely related. Industries use electricity supplied by Utilities through the grid network to power economic activity. While some industries use co-generation (as described in a previous blog) to power their operations, co-generation is not always viable.
In a previous blog post, we reviewed the architecture of the Indian electricity network wherein load despatch centers across the country ensure integrated operation of the power system. Entities connected to the electricity grid have to mandatorily follow directions issued by the load despatch centers. In the present iteration of the power system, where two-way power flow to and from the grid is a given, load despatch centers demand a high level of monitoring of energy flow to and from the grid.
Thus, Utilities and other network operators ensure that any industrial facility using power from the electricity grid transmits data such as energy parameters, breaker status signals etc. In this blog post, we will discuss how industrial facilities can achieve these objectives through energy management solution and optical ground wire (OPGW) connectivity.
Scope of work
In this project, SCOPE was provided the mandate by a leading defense industry major to supply, install & commission an automation system for interfacing the field inputs at industry- end substation and visualize these inputs locally by means of LDMS software. Additionally, the data is to be transmitted to Utility-end SCADA system as per the statutory requirement of the Utility
How to achieve this objective?
After review, SCOPE experts determined that for the industrial facility to send its field parameters data to the transmission utility, RTU based automation system has to be established at the substation of the industrial facility. With this in mind, the project was divided into two components:
Part 1: Field data interfacing & local monitoring system
- In order to interface the field data like status signals, energy parameters, analog parameters over 4-20 mA etc., an interfacing device/controller needs to be installed
- This interfacing device can be a full-fledged RTU, a FRTU, a DCU, a smart modem or an IOT sensor based on the application of signals needs to be interfaced
- However, SCOPE experts determined that the optimal solution would be an RTU system, which will interface all the required monitoring parameters such as, DI signals, AI signals, energy parameters over Modbus RTU protocol, other transducers parameter either as AI signals or over Modbus RTU protocol
- The RTU generally has its own LDMS software, which is a web HMI that can be used to visualize the field parameters taken by the RTU on a real-time basis
With these aspects in mind, SCOPE experts executed this phase of the project in the following manner:
- RTU with configuration of 48 DI ports, 02 RS485/RS232 ports, 02 RJ45 ports, IEC 60870-5-101/104 server protocol, Modbus RTU client protocol were supplied
- Two numbers of such RTUs with panel and accessories were supplied as per I/O requirement & signals lists of the project
- Field-end devices & cables and IT devices such as, DCPS with battery charger, CMRs, DC-DC converters, DI status cable, MFM signal cable, AC & DC supply cable, telephone cable, laser printer and industrial PC were provided
- Installed RTU are taking the DI status signals of the feeders and the energy parameters of the feeders by looping all the existing meters of the feeders. The energy parameters are displayed in LDMS software for real time monitoring at industry control center end
- The RTU is also acting as a gateway device to send the data to remote Utility- end SCADA system over IEC 60870-5-104 protocol
Part 2: Communication infrastructure for transmission of field inputs to the transmission utility
- The main objective here is to ensure the visibility of industry end substation parameters at the Utility- end SCADA system
- Normally the Utility- end SCADA would be housed a fair distance away from the RTU system installed at the industry end substation
- Thus, the question of data transmission remains. While determining the appropriate solution, SCOPE experts noted that in this instance, a medium of communication network needs to be established. Alternatives are: a) GRPS communication network, b) lease line communication network, c) dedicated fiber communication network, d) PLCC communication network and finally, e) OPGW communication network.
- The selection of any one type of communication media depends on the application points such as distance of communication, serial or IP based communication, cost implications, reliability requirements etc.
- After reviewing all alternatives, SCOPE experts settled on an OPGW communication network. This network is one of the most advanced modes of communication and well preferred by Utilities and industry experts.
|What is OPGW communication network? Why is it the industry preferred communication solution? |
Let’s discuss the OPGW communication network in detail (Source: Wikipedia article on Optical ground wire). An optical ground wire, alternatively called optical fiber composite overhead ground wire is a type of cable that is used aside overhead power lines to provide grounding protection for high voltage networks along with reliable point to point communication. The OPGW cable is run between the tops of high-voltage electricity towers. The conductive part of the cable serves to bond adjacent towers to earth ground, and shields the high-voltage conductors from lightning strikes. The optical fibers within the cable is used for high-speed transmission of data, either for the electrical utility’s own purposes of protection and control of the transmission line, for the utility’s own voice and data communication, or may be leased or sold to third parties to serve as a high-speed fiber interconnection between cities .
Construction of OPGW Cable OPGW network over Transmission Tower
Communication network was set up in the following manner:
- OPGW cable was laid from the industry end substation to the Utility- end control center through overhead tower line
- Splicing of LIU & Joint Box at both industry end substation and Utility-end control center were done
- All networking accessories such as LIU with media converter, ethernet switch were installed to ensure the data from industry to the utility is being transmitted seamlessly
- Establishment of OPGW network ensures the communication is reliable without any data loss and at the same time acts as a ground/earth wire for the towers of the Utility in case of events like lightning strikes.
Benefits of the System
This project, apart from fulfilling statutory requirements, ensures a win-win proposition for both industry and the Utility. By implementing the RTU based energy monitoring and substation status signals monitoring, data logging is automated, thereby ensuring greater accuracy. The OPGW network ensures reliable seamless transmission of energy parameters without any data loss by use of the existing infrastructure( in this case, transmission towers). It will ensure the utility utilizes the existing infrastructure to the fullest and reduces the dependency on any third party service provider like “Internet Service Provider” or “Dedicated Leased Line Service Provider”. We at SCOPE firmly believe that such projects are a good example of effective collaboration between Utility and industry; with improved energy auditing and transparency.
In this manner, SCOPE ensured the setting up of a state-of-the-art setting up of a solution for transfer of data from industry-end substation to the Utility-end SCADA. To know more about this solution, please write to us at firstname.lastname@example.org