08-09-2016, 02:34 PM
1453881657-5.SCADAINELECTRICITYBILLING.doc (Size: 207.5 KB / Downloads: 5)
ABSTRACT:
Modern control systems are being developed day to day in such a way to attain a sophisticated control & a maximum error free system. SCADA is commonly used in power system control & protection. SCADA is one such system, which is being familiar along with new features of computational intelligence, embedded systems etc.
SCADA represents Supervisory Control And Data Acquisition. It can cover a larger web. It is used in substation, transmission control & maintenance.
We have mentioned the most common tasks of SCADA, which along with its additional features allows us to apply SCADA in the conventional electricity billing, to obtain a most error free system.
The over all view of the system is given through a well explanary schematic representation. The tasks of SCADA break the system into a no of blocks such as BCU, MTU, MMI, and DM etc. Here we have connected all these in a Metropolitan Area Network.
Because of this network concept we go for security policies to secure the system from snoopers. SCADA along with the newer technical concepts will give a new frame to the multi element systems.
We hope that our paper will give a full meaning to the objective to which we have aimed.
Supervisory Control And Data Acquisition system (SCADA) technology has evolved to successful multipurpose data utility management & control tools. SCADA is one such system that is being familiar along with computational intelligence. SCADA is a successful miscellaneous system that provides the reliability, data accuracy, control security with intelligent application.
SCADA IN POWER SYSTEMS:
SCADA system enables an electricity utility to remotely monitor, coordinate, control & operate transmission & distribution components in a real time mode from a remote location with acquisition of data for analysis and planning from one control location. For example SCADA system is to allow operators to control circuit breakers, disconnect switches, tap changing of transformers & phase shifter position (remotely).
At a central load dispatch center data such as current, voltage, power factor & breaker’s status are telemetered & displayed. This gives the operator an over all view of the distribution network. SCADA can provide status & measurements for distribution feeders at the substation. Distribution automation equipment can monitor selectionalising devices like switches, interrupters & fuses. It can also operate switches for circuit reconfuration, control voltage, read customers’ meters, implement time-of-day pricing & switch customer equipment to
manage load. This equipment significantly improves the functionality of distribution control center SCADA can be used extensively for compilation of extensive data & management of distribution systems. Distribution automation through SCADA directly leads to increased reliability of power for consumers & lower operating cost for the utility. The key features of the system are viz;
Faster execution of decisions.
Manual errors & oversights are eliminated.
Periodic reports for performance analysis of the power system.
TASKS OF SCADA:
Other than the above features there are certain tasks in SCADA through which the entire control network is activated.
They are
Data collection:
It is responsible for periodically acquiring data from remote terminal units at the appropriate rate. In addition, data collection monitors the various scans to make sure they initiate & complete within the current time period.
Data transmission:
It refers to telemetry. The telemetry system comprises of an electronic equipment which converts the data received from the transducers into analogue or digital signals & transmits it to the control room for the use of computers.
Data monitoring:
Data monitoring is the process of periodic check up of the status of the data such as position of the CB, switches, fuses etc.
Man / Machine interface: The Man-Machine interface provides a link between the operator & the software/hardware used to control/monitor the power system.
APPLICATION OF SCADA IN ELECTRICITY BILLING:
The current features of SCADA is off-line processing with extensive manipulation of historical data, high processing power. It is quick in responding with high data throughput. These features allow us to apply SCADA in Electricity Billing. Before viewing of SCADA application in this task, we have to see the major uncertainties in it. They can be accounted as follows,
Chances of human errors.
Presence of malpractices.
Failure in tariff collection.
Delay in tripping functions.
Human resource wastage.
SCADA clears out all the black outs in the conventional billing system. In this paper we made a wide view over this topic. The system description is as follows.
With the due consideration of the tasks of the modern SCADA, we can divide the SCADA billing system as follows,
Data acquisition.
Data transmission.
Remote Terminal Unit.
Master Terminal Unit
Man Machine Interface.
Data Acquisition:
Consumers as reference point the necessary data for billing is collected from the energy meter in the form of pulses. The digital meter is integrated with relay, micro-controller& modem.
On the basis of computational algorithm the data is collected & transmitted to the common media. The computational algorithm depends upon the meter constant (rev/kwhr for electromechanical meter & pulse/kwhr ). If the meter constant is 1000 pulse/kwhr the algorithm is in such a way that the data output is in the terms of 100 pulse ie(.1 kwhr). This is done via micro-controller programming. The data transmitted is of the following format,
Address word -> refers to the consumer identification no.
Units -> refer to the no of units consumed at the time of request.
The data from the micro-controller is not of transmittable form. It is in the logic levels of a chip circuitry. Because of this, a modem or data conditioning is interfaced with the micro-controller. Now the data is fed to the common media, which is linked with the RTU via any network topology (preferably star network).
Data transmission:
Data transmission in SCADA billing is done in two ways,
Between consumers & RTU.
Between RTU & MTU.
RTU & Consumer Communication:
The data-word from the meter circuit of the consumer is transmitted to the RTU for updating activities. Similarly a command-word is transmitted from RTU to the meter circuit. These two transmissions take place in a single common media such as co-axial cable, optic fiber, and power line carrier
MTU & RTU communication:
The data collected in the RTU are transmitted to the MTU for further processing & similarly the processed data has to be fed back to the RTU for the process of bill collection. This is achieved by providing a server –client communication between MTU & RTU. In the MTU side routers are placed so that the high speed MTU processer is capable of communicating with a larger no of RTUs.
Depending on the media used the other accessories differ.
NETWORKING TOPOLOGY:
The whole system is based on MAN (Metropolitan area network). Here it’s a combination of two. This two can be extended between the regions are
Consumers’ & RTU
RTU&MTU.
The bus topology is a pertinent topology that can be utilized between consumers and RTU.The multipoint bus topology uses along cable to link the entire consumer’s in the network. In this way the network is established effectively. Here the bi-directional process can be done.
Following this the star topology is extended between RTU&MTU.In this topology, each RTU Is connected to a central controller called MTU. The link between these two can be accomplished through modem &router.
REMOTE TERMINAL UNIT:
The SCADA system consists of one or more computers with appropriate application software (master station) connected by a no of communication system to a no of remote terminal units placed at various locations to collect data, for remote control.
Remote terminal units play a vital role in this system in data acquisition that is, collection of the readings from a no of consumers’ meters & also behaves as a zonal collection center for the bills. The data from the consumers’ meters are stored in their respective web pages Fig: web page in the RTU
In the web page there are different fields in regarding the role of data acquisition, for instance the starting & current reading are used to store the data from the consumer, while the fields units, charge, fine are used to store the data results from the MTU. The field ‘paid’ is to register the payment of the consumer.
The RTU is otherwise called as Bay control unit when the tasks like remote control & monitoring are added with the RTU. The interfacing devices like modem are added depending upon the need on communication.
MASTER TERMINAL UNIT:
The data from the RTU are collected in the MTU for further processing. Depending upon the application software in the MTU the collected data get processed. The application software is developed using a high level language like c, c++ etc. the data from the RTUs are collected on the basis of the priority table in the priority table is made on the basis of the algorithm in the router i.e, priority may be
on the basis of shortest distance .