LOAD DISPATCH CENTRE
DEPARTMENT OF ELECTRICAL ENGINEERING
COLLEGE OF ENGINEERING
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1. LOAD DISPATCH CENTRE, KALAMASSERY, KOCHI
India is divided into 5 regions for power system planning and operation. These are Northern region, Southern region, Western region, Eastern region and North-Eastern region. The load dispatch centre for southern region is at Bangalore.
LOAD DISPATCH CENTRE, KALAMASSERY
The grid is managed by the State Load Dispatch Station situated at Kalamassery. There are 3 Sub Load Dispatch Centres – at Thiruvananthapuram, Kalamassery and Kannur (Kanhirode).The Load Dispatch activities are carried out with the aid of state of art technology computerized Supervisory Control and Data Acquisition System (SCADA). Real-time data from 30 Remote Terminal Units including generating stations and major sub-stations are acquired at the Load Dispatch Station. One more RTU is being installed. The data acquisition is through the communication network installed and maintained by the Board comprising of MW link from Thiruvananthapuram to Kalamassery and FO link from Kalamassery to Kannur.Data from remote stations are collected through Power Line Carrier Communication Network (PLCC) to the nearest nodal station in the broadband network. The state LD Station is connected to the Regional Load Dispatch Centre, Bangalore through FO link for real time data transfer. The real time generation details of all central sector stations are made available through the SRLDC.
The state load dispatch centre schedules generation from various generating stations, central sector stations and IPPs depending on the load condition and the real time frequency. Transaction of unscheduled energy from the pool when the frequency profile is favorable is coordinated by the SLDC effectively. The load Dispatch Centre also monitors the transmission system and issues sanction for shutdowns. Water availability, inflow, consumption, demand etc. are daily collected and monitored in the Load Dispatch Station.
The Load Dispatch activities are co-ordinated bythe Chief Engineer, System Operation, Kalamassery. The major activities undertaken by this wing are
1 Daily scheduling of Generation
2 Short term and long term planning of generation schedule
3 Preparation of Load Generation Balance Reports on short term and long term basis
4 Verification of energy drawals from various central generating stations and Regional Energy Accounts
5 Verification of energy availed on unscheduled basis from the central grid depending on the frequency.
6 Certification of energy generated from all internal generating stations and the energy received on the grid.
7 Maintenance scheduling of generating units and transmission lines.
8 Economic load dispatching
9 Grid discipline
10 Load forecasting and demand estimation
11 System security and islanding facility
12 Black start preparedness
13 Event analysis and preventive measures
14 Coordination with neighbor Grids
15 Public relation and consumer interaction.
16 Certification of availability of generating stations, and transmission system.
17 Maintenance of the communication network, communication equipments and SCADA system
18 Protection coordination, commissioning and troubleshooting of protection schemes at all substations and generating stations.
19 Performance monitoring of major grid elements like power transformers, instrument transformers, generators, capacitor banks, etc.
20 Undertakes testing and commissioning of protection schemes of major EHT consumers on a payment basis.
The Load Dispatch Station activities are technically supported by the communication wing and protection wing under the control of three Dy. Chief Engineers stationed at Thiruvananthapuram, Kalamassery and Kannur. The communication wing is responsible for the upkeep of all communication networks, the SCADA system and the associated software for Energy Management. The Protection Wing, more popularly known the Relay Wing, is responsible for ensuring selectivity and sensitivity to fault clearance in the grid to achieve stability of the power system. The LD Activities are controlled by the Dy.Chief Engineer, Grid, stationed at Kalamassery. The LD activities aim at the optimum usage of hydel reserves, unscheduled energy and follow the principles of merit order dispatch to minimize the operating cost of the grid.
SCADA is an acronym for Supervisory Control And Data Acquisition. SCADA systems use computer and communication techniques to automate the monitoring and control of industrial process. These systems improve the efficiency of the monitoring and control process by providing timely information so that appropriate timely decisions can be made. The purpose of SCADA is to allow operators to observe and control the power system. It supports both energy management and power system automation.
GENERAL SCHEME FOR A DATA ACQUISITION SYSTEM
Data acquisition is the process of sampling signals that measure real world physical conditions and converting the resulting samples into digital numeric values that can be manipulated by a computer. Data acquisition systems (abbreviated with the acronym DAS or DAQ) typically convert analog waveforms into digital values for processing. The components of data acquisition systems include:
• Sensors that convert physical parameters to electrical signals.
• Signal conditioning circuitry to convert sensor signals into a form that can be converted to digital values.
• Analog-to-digital converters, which convert conditioned sensor signals to digital values.
COMPONENTS OF SCADA SYSTEM
System Components: The four major SCADA system components include the
• Master Terminal Unit (MTU)
• The Remote Terminal Unit (RTU)
• Communication equipment and
• SCADA software.
The MTU is located at the operator’s central control facility and provides a man-machine software interface, two-way data communication and monitoring/control of remote field devices.
The RTU is a rugged computer with a very good radio interfacing .It is used in stations were communications are more difficult. The RTU, located at a remote site, gathers data from field devices (pumps, valves, alarms, etc.) into memory until the MTU initiates a send command. The central processing unit within the RTU receives a data stream via hardware equipment protocol.
When the RTU sees its specific address embedded in the protocol, data is interpreted and the CPU directs the specified action to take. The protocol used can be open like Modbus, TCP/IP or a proprietary closed protocol. Some RTUs, called “smart PLCs” or remote access PLCs, provide remote programmable functionality while retaining the communications capability of an RTU. These devices are designed to perform control functions, check site conditions, re-program anytime from anywhere, and have any alarm or event trigger a call to a personal computer without any direction from the MTU. The communication network is a medium for transferring information from one location to another. This can be via a telephone line, audio or cable.