基于微控制器的监测系统外文文献毕业设计（论文）.doc

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1、AN EFFICIENT MONITORING OF SUBSTATIONS USINGMICROCONTROLLER BASED MONITORING SYSTEMABSTRACT The paper proposes an innovative design to develop a system based on AVR micro controller that is used for monitoring the voltage, current and temperature of a distribution transformer in a substation and to

2、protect the system from the rise in mentioned parameters. Providing the protection to the distribution transformer can be accomplished by shutting down the entire unit with the aid of the Radio frequency Communication. Moreover the system displays the same on a PC at the main station which is at a r

3、emote place. Furthermore it is capable of recognizing the break downs caused due to overload, high temperature and over voltage. The design generally consists of two units, one in the substation unit, called as transmitter and display unit, and another in the Main station called as controlling unit.

4、 The transmitter and the display units in the substation is where the voltage, current and temperature are monitored continuously by AVR microcontroller and is displayed through the display unit. An RF transmitter is used for transmitting the signals that are obtained. The controlling unit in the ma

5、in station by means of a PC and a RF receiver receives the RF signals that are transmitted by the Transmitter unit and reacts in accordance to the received signal. In general, the proposed design is developed for the user to easily recognize the distribution transformer that is suffered by any open

6、or short circuit and rise in temperatures. The ultimate objective is to monitor the electrical parameters continuously and hence to guard the burning of distribution transformer or power transformer due to the constraints such as overload, over temperature and input high voltage. If any of these val

7、ues increases beyond the limit then the entire unit is shut down by the designed controlling unitKeywords: Electricity, Power Transmission systems, Substations, Distribution Transformers, Generators, Microcontrollers.1. INTRODUCTIONElectricity is an extremely handy and useful form of energy. It play

8、s an ever growing role in our modern industrialized society. The electrical power systems are highly non-linear 23, extremely huge and complex networks 22. Such electric power systems are unified for economical benefits, increased reliability and operational advantages 19. They are one of the most s

9、ignificant elements of both national and global infrastructure, and when these systems collapse it leads to major direct and indirect impacts on the economy and national security 2. A power system consists of components such as generators, lines, transformers, loads, switches and compensators. Howev

10、er, a widely dispersed power sources and loads are the general configuration of modern power systems 3.Electric power systems can be divided into two sub-systems, namely, transmission systems and distribution systems. The main process of a transmission system is to transfer electric power from elect

11、ric generators to customer area, whereas a distribution system provides an ultimate link between high voltage transmission systems and consumer services 15. In other words, the power is distributed to different customers from the distribution system through feeders, distributors and service mains 21

12、. Supplying electricity to consumers necessitates power generation, transmission, and distribution 4. Initially electric power is generated by using electric generators such as: nuclear power generators, thermal power generators and hydraulic power generators and then transmitted through transmissio

13、n systems using high voltage. Power departs from the generator and enters into a transmission substation, where huge transformers convert the generators voltage to extremely high voltages (155kV to 765 kV) for longdistance (up to about 300 miles) transmission 4. Then, the voltage level is reduced us

14、ing transformers and power is transferred to customers through electric power distribution systems. Power starts from the transmission grid at distribution substations where the voltage is stepped-down (typically to less than 10kV) and carried by smaller distribution lines to supply commercial, resi

15、dential, and industrial users 4. Novel electric power systems encompassing of power transmission and distribution grids consist of copious number of distributed, autonomously managed, capital-intensive assets. Such assets comprise: 1.) power plants, 2.) transmission lines, 3.) transformers, and 4.)

16、protection equipment 1.Efficient Monitoring of Substations 64 Electric utility substations are used in both the transmission and distribution system and operate independently to generate the electricity. A typical substation facility consists of a small building with a fenced-in yard that containstr

17、ansformers, switches, voltage regulators, and metering equipment that are used to adjust voltages and monitor circuits 4. A reliable and efficient process of these networks alone is not very significant when these electricity systems are pressed to their parameters of its performance, but also under

18、 regular operating conditions. Generators and loads are some components that coerce the continuous dynamic behavior 5. The distance between the Generators and loads may be in terms of hundreds of miles. Hence, the amount of huge power exchanges over long distances has turned out as a result of the l

19、ack of quality of the electric power. During the earlier development stages the issues on quality of power were not frequently reported. Quality of supply is a mixture of both voltage quality and the non-technical features of the interaction from the power network to its customers 18. Demanding the

20、quantity of power being delivered at the user side has raised the alarm due to the increase in demand of electricity in the customers side. The power generated at the main stations is transported hundreds of miles using transmission lines before they reach the substations. A huge amount of power is

21、lost during the transportation of the generated power which leads to the reduction in the quantity of power received at the substations. Also the electric lines users have identified that the number of drawbacks caused by electrical power quality variations are increasing rapidly. These variations h

22、ave already existed on electrical systems, but recently they are causing serious problems 6. Therefore, measurements must be acquired either from one end or from both the ends of a faulted line. Only meager recorded data is available at limited substation locations in certain systems. When a fault o

23、ccurs in such systems, only a few (two or three) recording devices are triggered. The most likely case is that the measurements could not be obtained at either or both ends of the faulted transmission line 16 leads to drop in the quality of the power.To improve the quality of power with sufficient s

24、olutions, it is necessary to be familiar with what sort of constraint has occurred. Additionally, if there is any inadequacy in the protection, monitoring and control of a power system, the system might become unstable 20. Therefore, it necessitates a monitoring system that is able to automatically

25、detect, monitor, typify and classify the existing constraints on electrical lines. This brings up advantages to both end users and utility companies 6. In general, distributed control agents are employed to offer reactive control at several places on the power network through the devices namely: 1.)

26、 Power System Stabilizers (PSSs), 2.) Automatic Voltage Regulators (AVRs), 3.) FACTS and much more 3. Monitoring systems offers an opportunity to record each and every relevant value that is present in a local database 7. An effective and well-organized state of monitoring is much significant in gua

27、ranteeing the safe running of power transformers. Potential breakdown of the power transformers can be recognized in their incipient phases of development by an excellent state of monitoring sothat the maintenance of the power transformers can be condition based in addition to periodically scheduled

28、 8.During the past years a number of researches were undergone with the help of microprocessors and controllers for continuous monitoring of sample concentrations, the behavior of analysts at different time intervals 17, monitoring the voltage, current and temperature fluctuations in the distributio

29、n transformers at the substations. The level of current and voltage at the substations may vary drastically due to the increase in temperature at the distribution transformers. Due to this the quality of power being delivered to the user might be insufficient. Hence monitoring the current, voltage a

30、nd additionally required parameters at the distribution side can aid in developing both the output generated at the main station and the quality of power being delivered at the customer side. It is also capable of recognizing the break downs caused due to overload, high temperature and over voltage.

31、 If the increase in temperature rises higher than the desirable temperature, the monitoring system will protect the distribution transformer by shutting down the unit.As discussed earlier, maintenance of a transformer is one of the biggest problems in the Electricity Board (EB). During strange event

32、s for some reasons the transformer is burned out due to the over load and short circuit in their winding. Also the oil temperature is increased due to the increase in the level of current flowing through their internal windings. This results in an unexpected raise in voltage, current or temperature

33、in the distribution transformer. Therefore, we are proposing the automation of the distribution transformer from the EB substation. In the automation, we consider the voltage, current and temperature as the parameters to be monitored as the transformer shows its peak sensitivity for the same. Hence,

34、 we design an automation system based on microcontroller which continuously monitors the transformer. Because of the microcontroller operation, the transformer present in the substation which is turned off in the main station. The rest of the paper is structured as follows. Section 2 presents a brie

35、f review of several approaches that are available in the literature for monitoring of power in distribution systems. Section 3 presents the technique along with its algorithm for monitoring and controlling the essential parameters of the distribution transformers using the system based on microcontr

36、oller. Section 4 details the three case studies analyzed in the paper and section 5 presents the conclusion. IJRRAS 4 (1) July 2010 Thiyagarajan & Palanivel. Efficient Monitoring of Substations652. RELATED WORKSThe process of rebuilding in the field of electricity industry results in a need of innov

37、ative techniques for representing a huge quantity of system data. Overbye and Weber 9 have presented a summary on various visualization techniques that might fairly be helpful for the representation of the data. The techniques such as: 1.)contouring, 2.) animation, 3.) data aggregation and, 4.) virt

38、ual environments must prove to be quite useful. Yet, important challenges remain. The major challenges are: 1.) the problem of visualizing not just the state of a existingsystem but also the potentially huge number of incident states, and, 2.) the problem of visualizing not just the impactof a solit

39、ary proposed power transfer but of a great number of such transactions.Johan Driesen et al. 10 have discussed the model of an flexible energy measurement system consisting of a DSP, sensor and communication units. The modern electricity distribution networks utilizes this system, featured by multipl

40、e suppliers in a deregulated market, bi-directional energy flows owing to the distributed generation and a diversified demand for the quality of electricity delivery. Different features of the system relating to signal processing, communication and dependability were discussed. Their work also inclu

41、des the examples of the use of such devices.Daponte et al. 6 have discussed the design and implementation of Transientmeter, a monitoring system for the detection, classification and measurement of disturbances on electrical power systems. CORBA architecture is utilized as communication interface by

42、 the Transientmeter, wavelet-based techniques for automatic signal classification and characterization, and a smart trigger circuit for the detection of disturbances. A measurement algorithm, developed by using the wavelet transform and wavelet networks, had been adopted for the automatic classifica

43、tion and measurement of disturbances.The results that are obtained after the process of monitoring a distribution transformer during a period of 18 months was described and discussed by Humberto Jimenez et al. 11. The transformer fed several households, each with a grid connected photovoltaic system

44、, and it was identified that the power factor at the transformer attained strange low levels. This was because of the fact that under some circumstances, the systems offers a great portion of the active power that is demanded by the households, whereas the grid supplied all the reactive and distorti

45、on powers. The operating temperature was used as an indicator for the pressure on transformer. The temperature level was least when the systems were providing the maximum energy available from the solar cells.Power quality monitoring systems are capable of detecting disturbances by means of Mathemat

46、ical Morphology (MM) very quickly. Yet, the signal under examination is frequently corrupted by noises, and the performance of the MM would be greatly degraded. Sen Ouyang and Jianhua Wang 12 have presented a quick process in order to detect the transient disturbances in a noisy atmosphere. In this

47、approach, the suitable morphologic structure element, appropriate mixture of the erosion and the dilation morphologic operators can develop the capability of MM. In addition, the soft-threshold denoising technique based on the Wavelet Transform (WT) was used for purpose of reference. Thus the abilit

48、ies of the MM can hence be restored. This technique has possessed the following merits: 1.) Great speed in calculation, 2.) easy implementation of hardware and, 3.) better use value. At last, the validity of the proposed technique is demonstrated by the outcome of the simulation and the actual field tests.The propagation of non-linear and time-variant loads leads to a copious number of disturbances on the electric network, from an extremely significant distortion of both currents and voltages, to transient disturbances on the supply voltage. In this respect the electric network