Overview

July 2012 ended with darkness gripping whole of north and north eastern India. The reasons were grid collapse. There had numerous article on why it happened, I am writing how its reoccurrence could be prevented. The prevention is a big subject to deal with and had number of dimension political, administrative, policy, demand and supply defiect and technology. I will be dealing with the technological aspect with emphasis on communication requirement of SCADA.

Transmission networks managed by utilities are required to maintain an uptime as high as 99.6%. Transmission utilities which operate long transmission lines require reliable communications for control of the power grid. The health of the network requires to be continuously monitored to take corrective actions. These actions help in restoring the balance of the system and preventing the wide spread Grid Failure (Such as those on 30th and 31st July). Protection of the transmission line from short circuits and other faults is usually so critical that common carrier telecommunications are insufficiently reliable, and in remote areas a common carrier may not be available. Communication systems associated with a transmission networks are:

• Microwaves
• Power line communication
• Optical fibers
• VSAT

 

Why VSAT?

The first three has their own advantages and disadvantages. In Indian context the disadvantages are making the situation favorable to the fourth technology i.e. VSAT. In Microwave the frequency has been allotted to defense while Power Line and Optical Fiber are plagued with sever delays. Most of the health monitoring network of transmission utilities in India is working offline. The utilities were under tremendous pressure from various bodies to rectify the situation. Post 30th and 31st July Grid collapse, the pressure has further increased to roll out the connectivity as soon as possible. In all the above technologies VSAT has the shortest roll out time.

 

Why Independent VSAT network?

In general the SCADA networks have swayed towards the adoption of private networks. The primary reasons are due to:

• The criticality of operating situation requires own the control of the network

• Available carrier services are not covering all areas required. The own network is designed to cover the whole territory

• Guaranteed and controlled network performance against a common carrier service, which is a shared medium

A separate owned network of VSAT at the SLDC (the monitoring center of Transmission utilities) fits very well in the situation. Example of KPTCL (Karnataka Power Transmission Corporation) is pertinent here. KPTCL own a VSAT network for meeting there monitoring need. KPTCL has been using the network for purpose of meeting their other communication requirement.

 

Co-located VSAT Network: An answer to the customer requirement

The following reasons had necessitated for rethink for new services to meet the requirement of Transmission companies:

• Recent regulatory changes: Hike in Licensee fee, licensing procedure.

• Scarcity of Satellite Bandwidth : Sever crunch due to failure of satellite launch

• Cost of owning a complete separated network and associated infrastructure

• Operational difficulty in maintain the network at distant remote locations

Co-located services are quite popular in the data center, where service providers provide service and various components could be owned / rented /leased by the service provider. We would like to propose similar model for VSAT based network. The following will be the components of the purposed solutions to transmission companies:

• Separate Outbound at premises of the Service Provider.

• Space, Power, Antenna and Amplifier to be provided by Service provider as common infrastructure.

• Bandwidth to be provided by service Provider

• Installation and Maintenance of the remotes.

• NMS to be pulled out and provided at the SLDC, with all control to customer.

• Manpower at the hub for maintenance of the network.

 

Co-located service: A win proposition

The above solution is to meet the following requirement of the customer:

• Faster roll out to meet the obligation of a centrally monitored network

• Separate Network, with complete control over the network by customer.

• To meet the uptime and reliability requirement of the transmission network.

As the co-located VSAT service could be rolled out at faster pace the monitoring/ SCADA network would become online. The communication network will provide data to continuously monitor the Grid’s health. Ultimately reducing the venerability of the Grid.