IN RECENT YEARS, SIGNIFICANT RESEARCH EFFORTS HAVEBEEN DEVOTED TO THE OPTIMAL PLANNING OF POWER SYSTEMS.Substation EXPANSION PLANNING (SEP) AS A SUB-SYSTEM OF POWERSYSTEM PLANNING CONSISTS OF FINDING THE MOST ECONOMICAL SOLUTIONWITH THE OPTIMAL LOCATION AND SIZE OF FUTURE SubstationS AND/ORFEEDERS TO MEET THE FUTURE DEMAND. THE LARGE NUMBER OF DESIGNVARIABLES, AND COMBINATION OF DISCRETE AND CONTINUOUS VARIABLESMAKES THE Substation EXPANSION PLANNING A VERY CHALLENGINGPROBLEM. SO FAR, VARIOUS METHODS HAVE BEEN PRESENTED TO SOLVESUCH A COMPLICATED PROBLEM. SINCE THE BACTERIAL FORAGINGOPTIMIZATION ALGORITHM (BFOA) HAS BEEN PROPER RESULTS INSTUDIES OF POWER SYSTEMS, AND HAS NOT BEEN APPLIED TO SEPPROBLEM YET, THIS PAPER DEVELOPS A NEW BFO-BASED METHOD TOSOLVE THE SEP PROBLEM. THE TECHNIQUE DISCUSSED IN THIS PAPERUSES BFOA TO SIMULTANEOUSLY OPTIMIZE THE SIZES AND LOCATIONS OFBOTH THE EXISTING AND NEW INSTALLED Substation AND FEEDERS BYCONSIDERING RELIABILITY CONSTRAINTS. TO CLARIFY THE CAPABILITIES OFTHE PRESENTED METHOD A TYPICAL NETWORK IS CONSIDERED AND THERESULTS OF APPLYING GA AND BFOA ON THE NETWORK ARE COMPARED.THE SIMULATION RESULTS DEMONSTRATE THAT THE BFOA HAS THEPOTENTIAL TO FIND MORE OPTIMAL RESULTS THAN THE OTHER ALGORITHMUNDER THE SAME CONDITIONS. ALSO, THE FAST CONVERGENCE, CONSIDERATION OF REAL-WORLD NETWORKS LIMITATIONS AS PROBLEMCONSTRAINTS AND SIMPLICITY IN APPLYING TO LARGE SCALE NETWORKS ARETHE MAIN FEATURES OF THE PROPOSED METHOD.

MAIN GOAL OF DISTRIBUTION NETWORKS DESIGN AND EXPANSION IS TO RESPOND TO ELECTRICITY CONSUMPTION GROWTH WITH THE MOST EFFICIENCY, WHILE NOT CONTRAVENE THE CONSTRAINTS GOVERNING THE SYSTEM. HIGH AMOUNT OF INVESTMENT AND ALONG WITH THE EVER-INCREASING DEMAND FOR ENERGY AND EQUIPMENT PRICE GROWTH MAKE THE DESIGNERS CONCENTRATE ON MORE PRECISE AND SUITABLE WAYS TO DESIGN THESE NETWORKS. APPEARANCE OF DISTRIBUTED GENERATION IN DISTRIBUTION SYSTEMS IN ADDITION TO CHANGE IN OPERATION STAGES OF THESE SYSTEMS HAS PROVIDED THE ABILITY FOR THESE COMPANIES TO DESIGN SYSTEMS WITH LOWER COST. TO GAIN THIS GOAL, THE DESIGN OF DISTRIBUTION SYSTEMS SHOULD BE REVISED. THIS PAPER PRESENTS A NEW METHOD TO OBTAIN THE NUMBER, LOCATION, CAPACITY AND SERVICING AREA OF EACH SUB-TRANSMISSION Substation THROUGH CANDIDATE AND AVAILABLE Substation LOCATIONS, CONSIDERING THE POSSIBILITY OF DG INSTALLATION ON ANY OF LOAD CENTERS, WHERE THE UNCERTAINTY OF FORECASTED LOAD OF EACH LOAD CENTER IS CONSIDERED AS A FUZZY MODEL. IN THIS METHOD THE OPTIMIZATION IS PERFORMED USING GENETIC ALGORITHM WITH CONSTRAINTS INCLUDING VOLTAGE DROP, SubstationS AND DGS LOADING CAPACITY AND UNIDIRECTIONAL CONNECTION BETWEEN SubstationS AND LOADS.

DIGITAL AND IT TECHNOLOGY HAVE BEEN DEVELOPED IN RECENT YEARS, SO THE CONVENTIONAL Substation CONTROL HAS CHANGED TO DISTRIBUTED AND DIGITAL CONTROL SYSTEM. ONE FEATURE OF EVERY SYSTEM IS AVAILABILITY, SO IN THIS PAPER, THE AVAILABILITY OF TRANSMITTAL CONTROL FUNCTION FROM Substation OR NETWORK LEVEL OF SOME Substation CONTROL SYSTEM ARE COMPARED. THESE RESULTS HAVE BEEN DERIVED:THE SIMPLE STAR TOPOLOGY HAS LOW MTTF AND RELIABILITY, BUT BY CONSIDERING SEPARATE HMI AND SERVER GATEWAY, THESE FEATURES INCREASE RAPIDLY. IF A REMOTE HMI ADDED, THE MTTF INCREASED BUT A LITTLE, BECAUSE OF REDUNDANCY IN A SMALL PART OF SYSTEM LIKE HMI.BY CONSIDERING SERIAL SWITCH FOR COMMUNICATION TO NETWORK LEVEL WHEN NCC SERVER AND SA SERVER ARE THE SAME, THE RELIABILITY DECREASES BECAUSE OF SERIAL COMPONENTIT YIELD THAT RING TOPOLOGY HAS LESS AVAILABILITY THAN STAR TOPOLOGY.IN RTU_BASED SYSTEMS, BECAUSE OF SIMPLICITY OF I/O UNITS AND THEIR BETTER MTTF, THE AVAILABILITY IS BETTER THAN SA SYSTEM. BUT, WHEN MAINTENANCE IS CONSIDERED, BECAUSE OF COMMON CONTROL COMPONENT (RTU) AND LOSS OF REDUNDANCY, THE AVAILABILITY BECOMES LESSER THAN SA SYSTEM.

THE PAPER PROVIDES A BRIEF EXPLANATION OF THE AUTOMATION AND SCADA INDUSTRY ALONG WITH NETWORKING SCHEMES. PROTOCOLS AS A CRUCIAL PART OF THE SYSTEM ARE EXPLORED IN DEPTH. IN ADDITION, COMMONLY USED PROTOCOLS AND STANDARDS ARE MENTIONED CONCISELY. THE NEWEST INVENTION OF THE IEC STANDARDS COMMITTEE, KNOWN AS IEC 61850, IS ALSO INTRODUCED. IEC 61850 AND UCA HAVE PROMISING ADVANTAGES OVER OTHER PROTOCOLS AND WILL GREATLY CHANGE SCADA SYSTEMS TODAY. ALSO, A GENERAL GUIDELINE IS PROVIDED FOR PROTOCOLS, WHICH IS THEN USED TO CREATE A COMPARISON CHART FOR THEM.

ONE OF THE MOST IMPORTANT COMPONENTS OF THE SubstationS IS THE AUXILIARY POWER SUPPLY SYSTEM. UNDER NORMAL OPERATION, THE BATTERY CHARGER SUPPLIES THE CONTINUOUS LOADS AND CHARGES THE BATTERY, AND THE BATTERY SUPPLIES POWER TO THE MOMENTARY LOADS. IF A FAILURE OF THE AC SYSTEMS OCCURS, THE BATTERIES SHOULD SUPPORT THE REQUIRED POWER FOR THE DC LOADS ON THE AUXILIARY DC SYSTEMS AS WELL. HOWEVER, THESE CONDITIONS MAY CONTINUE FOR SEVERAL HOURS. UPON LONG OUTAGE DURATION, THE BATTERY SUPPLY WOULD FAIL TO SUPPORT THE LOADS. THEREFORE, THE OUTAGE DURATION OF A BATTERY CHARGER AS WELL AS THE CORRECT SIZING OF THE BATTERY IS A CRITICAL FACTOR FOR DESIGNERS AND NETWORK PLANNERS. THIS PAPER SUGGESTS AN INNOVATIVE SOLUTION TO USE A COMBINATION OF RENEWABLE GENERATIONS AND STORAGE SYSTEMS IN DISTRIBUTION SubstationS TO ENHANCE THE ENERGY EFFICIENCY OF THE SYSTEM ESPECIALLY IN LONG LASTING POWER OUTAGES. TO ASSESS THE EFFICIENCY OF THIS METHOD, THE DESIGN OF THE PHOTOVOLTAIC SYSTEMS WOULD BE APPLIED TO THE QODS CITY Substation, ONE OF THE PROJECTS CARRIED OUT IN NIROO CONSULTING ENGINEERS COMPANY, AS THE CASE STUDY OF THIS WORK. THE GOAL OF THIS DESIGN IN COMPETITIVE ADVANTAGE ANALYSIS IS TO PROVE AND SHOW THAT BY USING THE PROPOSED PHOTOVOLTAIC AUXILIARY DC POWER SYSTEMS IN THE SubstationS VERSUS THE DISTRIBUTION SYSTEMS, THE RELIABILITY OF THE SubstationS, AND CONSEQUENTLY, UTILITY GRID WILL BE INCREASED.

ENGINEERS TO DESIGN DISTRIBUTION NETWORK CAN DECIDE DIFFERENT ALTERNATIVE FOR EXAMPLE PLACEMENT AND CAPACITY NEED TO ANALYSIS LOCATION AND CAPACITY OF OTHER DISTRIBUTION Substation .SO DECISION AFFECT THE LOCATION NEIGHBOUR Substation .IN THIS CASE THE INPUT INFORMATION IS IMPORTANT AND CALCULATION IS IN DIRECT FAMILY WITH INFORMATION FOR EXAMPLE FOR Substation LOCATION YOU CAN SEE THE PAPER THAT LOADS ARE ASSUME CONSTANT THEREFORE MOST OF STUDIES BASE ON CONSTANT LOAD AND NORMALLY USE MAXIMUM OF LOAD CURVE TO DEFINE Substation SITUATION, ALTHOUGH MAXIMUM LOAD IS HAPPEN IN SHORT PERIOD AND LOAD CURVE IS DIFFERENT IN DAY SO THE OPTIMUM LOCATION FOR HOURS IS DIFFERENT .IN THIS STUDY TRY TO FIND THE LOAD POINT SITUATION ,ASSUME LOAD CURVE AND USE THE PROBABILITY METHODOLOGY.