05-10-2016, 04:13 PM
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Abstract
The demand for electrical energy is increasing now days . This article discusses the plant's electrical/steam load balance issues and the development of a high speed load shedding scheme. Around 20-25% of energy generated is lost in transmission & distribution system . As we know , reduction in distribution losses can reduce power deficit . There is a possibility to bring down the distribution losses in India with the help of newer technological option (including information technology) in the electrical power distribution sector which will enable better monitoring and control. This project “ fast load shedding & monitoring system” is designed such that the distribution network can be monitored & fast load shedding could be done from a large centralized system . the centralized system will get real time data from distribution network . Shedding will be done, according to the real time data, by just send command to relay of a particular distribution point.
Introduction
Most common problems that we face is monitoring all these feeders, substation, Distribution Transformers and Distribution points from one central location.. In this project we will be making a prototype to monitor a distribution point from a central location and if any problem occurs information will be sent to the central unit. Moreover theft is also quite common at the distribution points as it is not possible for someone to monitor them24 hours.
When load shedding occurs in an area the complete power to the concerned area is cut off, these include street lights, traffic signals and important utilities like hospitals, police stations & fire brigade even their power is turned OFF. In this project the central control unit can cut off the power to specific area by just sending an SMS to the concerned Distribution Point there by retaining power for the basic utilities.
In this project we will be monitoring current of two zones which are being diverted via the Distribution Point. Two relays are also provided to cut off the loads in these two zones for load shedding or any other emergency purpose. A sensor is provided to check if the door of the DP
is open or closed so whenever the door is opened an SMS is sent to the central system as well as to the concerned electrician responsible for that DP.
METHODOLOGY
The purpose of electric power system is to attach the power system to consumers loads. An electric power system consists three parts:
1. Power generation
2 .Transmission system
3. Distribution system
Electric power is generated at 11kV in a power generating station . For transmitting over long distances, it is then stepped-up to 400kV, 220 kV as it is necessary to reduce losses while transmitting power. Power is carried through a transmission network of high voltage lines. Usually, these voltage lines run into hundreds of kilometers and it deliver to grid.
These grid is connected to load centers (cities) through a sub-transmission network of normally 33kV (or sometimes 66kV) lines. These lines terminate into a 33kV (or 66kV) at substation, where the voltage is stepped-down to 11kV for power distribution to load points through a distribution network of lines at 11kV and lower
This section depicts a review of a number of load shedding.
1. Manual load shedding technique :
In the load shedding process at substation who perform cut of the power for certain period of time to control shortage of electrical energy used by locality.
In manual load shedding supply of some area are manually cut down by the electrician for a period of time. Electricians are engaged at substation. In this way the load shedding done by manually at substation to cut of the power.
2. SMS based electrically load Shedding:
In this method the distribution point monitored by one central location. The relays are used to cut off supply of concerned zone through circuit breaker . in this system user can send commands to read the remote electrical parameters . This system can be automatically send the real time electrical parameter data like active power, supply voltage, current, reactive power , frequency etc periodically in the form of SMS to the user. It can be designed to send SMS alerts when relay trips. In this system micro-controller are used to effectively communicate with the sensors. The controller has internal memory to hold the assembly code. .This internal memory is used to dump some set of assembly instructions into the controller. The functioning of the micro-controller is dependent on the these assembly instructions.
PROPOSED SYSTEM
The proposed system will overcome manual efforts for controlling the load shedding time interlude in a systematic way by sending SMS. Central unit can cut off power supply of specific zone by just sending an SMS to the concerned Distribution Point . These relay gets activated whenever the electrical parameters exceed the predefined values. The proposed system is designed to Load Monitoring .
We continuously watch the system load by measuring the input rates and estimating the load level on each server accordingly.
For this system, the following requirements are there:
• Micro-controller
• Current transformer
• Signal conditioning
• ADC
• Relay
• GSM
• EEPROM
1)MICROCONTROLLER:
microcontroller collect data from CT through ADC . controller monitores output data of ADC which is displaced on LCD The controller has the internal memory to hold the code. .This internal memory is used to dump some set of assembly instructions into the controller.
2) CURRENT TRANSFORMER:
As we know input from the dpwhich is in high ampere of current .Current transformers can reduce or “step-down” current levels from thousands of amperes down to a standard output of a known ratio to either 5 Amps or 1 Amp for normal operation. Thus, small and accurate instruments and control devices can be used with CT’s because they are insulated away from any high-voltage power lines.
3)SIGNAL CONDITIONING :
The output of current transformer is current. The signal conditioning circuit used to convert current into the voltage and interfaced to ADC.
4)ADC:
The MCP3204 type ADC are used to interfacing with the controller. Which convert analog input to digital output.It converts the analog input from the DP and gives digital output to controller.
5) RELAYS :
A relay is an electromagnetic switch operated by a relatively small electric current that can turn on or off a much larger electric current. When current becomes zero it does load shedding . types & rating of relay is depend on our application
In relay, an iron core is surrounded by a control coil. the power source is given to the electromagnet through a control switch and through contacts to the load. When current starts flowing through the control coil, the electromagnet starts energizing and thus intensifies the magnetic field. Thus the upper contact arm starts to be attracted to the lower fixed arm and thus closes the contacts causing a short circuit for the power to the load. On the other hand, if the relay was already de-energized when the contacts were closed, then the contact move oppositely and make an open circuit.
6) GSM:
The SIM 900 GSM module is used for the communication between cental system & concerned DP .This module provide SMS functionality. Centralized control unit at any instance get the status by just sending an SMS to the DP. As SIM900 has the facility to read the received Message. we have written a Assembly program to control the DP through message without any hardware changes.
7) EEPROM :
It is secondary storage device that once written (programmed) can hold data even when the power is removed.EEPROM stands for electrically erasable programmable read only memory.
It is a type of non-volatile memory used in computers and other electronic devices to store small amounts of data that must be saved when power is removed. e.g. calibration tables or device configuration.
Various EEPROMS are available in market EEPROMS with I2C interface, with SPI interface, Micro wire & parallel interface.
8)MAX232:
MAX232 is used for interfacing of controller to PC. MAX 232 IC basically converts RS232 voltage level into TTL voltage level i.e. ±10V to 5V. MAX 232 is used not just used for PC interfacing. MAX 232 is used not just used for PC interfacing it is also used to interface following modules.
• GSM Module.
• GPS Module.
• RFID Reader.
• Bluetooth Modules.
• Wi-fi Modules.
CONCLUSION
The proposed system along with remote communication with SMS will be running automatically and minimized a huge amount of manual work and enhance efficiency to the existing manual system. Load shedding is one the main actions that can be used to prevent further spread of a wide area disturbance and restoration of the load generation balance in a separated part of the system.