Artificial Intelligence Substation Control


About

          Electric substations are facilities in charge of the voltage transformation to provide safe and effective energy to the consumers. This energy supply has to be carried out with sufficient quality and should guarantee the equipment security.  The associated cost to ensure quality and security during the supply in substations is high. 

                     Even  when all the magnitudes to be controlled cannot be included in the analysis  (mostly due to the great number of measurements and status variables of the substation and, therefore, to the rules that would be required by the controller), it is possible to control the desired status while supervising some important magnitudes as the voltage, power factor, and harmonic distortion, as well as the present status.

Experimental Results

          To carry out the experiment, a software for the platform windows 9x/2000 using Delphi was elaborated. Signal generators for the analog input variables were used.  The experiment was starting from the status 0011. During the first 400 measurments,243 actions could not be determined by the controller ,an expert gave the answers i.e., ,and as a result,243 new controller rules were extracted.


Plant Description

           The system under study represents a test substation with two 30KVA three-phase transformers, two CBs, two switches, three current transformers, and two potential transformers.  It also contains an auto transformer  (to regulate the input voltage) as well as impedance to simulate the existence of a transmission line.  The input voltage are the same  (220V), this characteristic was selected in order to analyze the operation of the controller in a laboratory scale in a second stage of the development of the present work. Therefore, the first transformer increases the voltage to a value of 13.2KV, while the second lowers it again to 220V. fixed filter, an automatic filter for the control of the power factor and the regulation of the voltage, and three feeding lines with diverse type of loads of different nature  (including nonlinear loads) are connected through CBs to the output bar. 

Inference Module

                 The  controller  outputs  are  decided  by  searching  in  the  rule  base.  In  this  step,  called  inference,  the  fire  degree  of  each  rule  is  calculated. Since  the consequence  part  in  each  rule  only  deals  with  status  variables  whose  values  are  crisp  numbers(0  and  1),  use  of  defuzzification  method  is  not  necessary. Therefore,  the  controller   output  in  each  case  will  be  the  consequent  part  of  the  rule  with  the  biggest  fire  degree.
       
 Abstract

Controlling a substation by a fuzzy controller speeds up response time diminishes up the possibility of risks normally related to human operations. The automation of electric substation is an area under constant development Our research has focused on, the Selection of the magnitude to be controlled, Definition  and  implementation  of  the  soft  techniques, Elaboration  of  a  programming  tool  to  execute  the  control  operations. it is possible to control the desired status while supervising some important magnitudes as the voltage, power factor, and harmonic distortion, as well as the present status. The status of the circuit breakers can be control by using a knowledge base that relates some of the operation magnitudes, mixing status variables with time variables and fuzzy sets .

Conclusion

Electric substations are facilities in charge of the voltage transformation to provide safe and effective energy to the consumers. This energy supply has to be carried out with sufficient quality and should guarantee the equipment security. The associated cost to ensure quality and security during the supply in substations is high. Automatic mechanisms are generally used in greater or lesser scale, although they mostly operate according to an individual control and protection logic related with the equipment itself.
  

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