BEST PRACTICES IN DISTRIBUTION LOSS REDUCTION
Distribution System Planning, Analysis, and Design
q GIS Based Mapping
q Software Based Distribution Network Analysis
q GIS Based Growth Planning
q Load Forecast Implications
Present Needs of Distribution Company to achieve effectiveness
q System management for quality power with minimum losses
q Efficient diagnosis of losses - Technical & Commercial
q Monitoring of commercial losses due to
q Malpractice
q Defective metering
q Lack of meters
q Undisciplined meter reading
q Effective Metering & Billing programme
q An effective vigilance system
q Prompt action on meter readers observation
q Optimum inventory management
q Proper customer complaints & grievance system
q Effective Man power utilization
Challenges
q Non availability of network information/data base
q Non existence of regular updating system
q Non-availability of any specific manual
q Non-availability of any IT enabled tool to provide requisite analytical reports correctly & quickly
q The distribution company cannot work efficiently and economically Without availability of consumer and technical data base
q Record day to day change in the system.
q Analysis & improvement of the system, will not be possible.
Solution - GIS data base & Distribution Analysis Software Package
What is GIS?
A Geographic Information System (GIS) is a computer-based tool for mapping and analyzing things that exist and events that happen in a spatial context.
GIS Benefits
Combined textural/spatial capabilities make GIS valuable to a wide range of public and private enterprises for
q Explaining events,
q Predicting outcomes and
q Planning strategies.
GIS Technology
GIS technology helps to
q Integrates common database operations (data query and statistical analysis), with the unique benefits of visualization and conceptual spatial analysis, offered by maps.
q Optimizes data layering (spatial overlays for object relationship identification),
q Allows for effective and timely data management (particularly data updates).
GIS based mapping for electrical network
The GIS mapping in the context of Electrical distribution network means Mapping of complete electrical network upto low voltage system and customer supply points with latitude and longitudes overlaid on satellite image and/or survey of India maps. It also covers incorporation of present details of localities, landmarks, network details upto consumer level
What is the Need?
q Inventory of Existing Network
q Easy access to Network details
q Easy access to Consumer Data
q Data export for Analysis & Network Improvement of existing system
q Load growth projections
What is required?
q Base Map (Digitized or image)
q DGPS (Differential Geographical Positioning System) to fix salient topographical details
q Handheld GPS (Global Positioning System)or Electronic Distance/Angle Measuring Equipment(EDM) to locate network details upto consumer level
q GIS package
Mapping procedure
q Preparation of Base Map
q Fixing Topographical Details
q GPS Survey
q Single Line Diagrams
q Preparation of Network in GIS package
Preparation of Base Map
q Obtaining the Base Map of the area to be mapped from ISRO/Remote Sensing Application Center/ SOI/other sources which would have coarse level information
q Digitization of Base Map
q Geo-referencing the Map
Fixing Topographical Details
Using DGPS (Differential Geographical Positioning System) the salient topographical details of the area like road junctions, important land marks can be accurately fixed.
GPS survey
Handheld GPS / Geo explorer/other system with resolution of 1m can be used to locate the substations /transformers /poles/ consumer points, etc
Attribute data of each pole and other facilities collected during the survey - such as asset data, Transformer details, services, type of use, load, consumer details, etc
Single line diagrams
q The GPS points will be used to plot the networks on the already digitized Base maps using suitable GIS Packages (AutoCAD map/ Map Info /Arcinfo/custom)
q Categorization codes can be used to identify the substations/transformers/poles/consumers, etc
q Attributes like Transformer details, load centres, type of use, HP of pumps, consumer details, etc tol be indicated for each equipment/pole
Attributes
Attributes for a Distribution trasnformer
Preparation of GIS
q GIS includes the GPS survey network overlaid on Base map with all attributes of each pole
q Includes inventory for asset management
q Includes loads on the system
q Also associated analysis
GIS Applications
Urban:
q Asset Management
q Location of faults
q Efficient planning of maintenance
q Effective network augmentation/upgradation
q Customer Management viz. Complaints, new services, etc
q Build in consumer data base covering consumption, billing and collections, etc
q Energy Audit & MIS
GIS Applications
Rural:
q Asset Management
q Efficient planning of maintenance
q Location of faults
q Effective network augmentation/upgradation
q Monitoring of consumption
q Energy Audit & MIS reports
Software based distribution network analysis
What is the need?
q Assessment of Voltage Regulation
q Peak Power Loss/Energy Loss of each system element to arrive at total technical loss
q Assessment of inadequacies of the existing ST&D system
q Inadequacy of the backup transmission system
q Security and reliability of the power supply
What does it provide?
Advantages of software based network analysis
q Very accurate analysis of Voltage variation, Energy loss, etc
q Less time requirement
q Graphical output
q Quick Output based on query for each facility/line
q What If analysis
q Manual method - More possibilities for error and Time consuming process, Laborious method
Available software for analysis
q SYNERGEE
q SMALL WORLD
q CYME
q POSCODOM
q PRAO
q WIND-MIL
q POWER MANAGEMENT
q MIPOWER, etc
How to proceed?
The major components of software based network analysis includes
q Mapping of the Network
q Information about facilities
q Loads
q Analysis
q Output
Mapping of the network
Import the GPS based Networks with actual lengths of each span, load centres, transformer points, etc into the software. Alternately the software can be clubbed with a GIS backend to collect information of network & its assets.
Information about facilities
q Assign the following details about the facilities
q Conductor type
q Conductor size
q Transformer details, etc
Loads
The reliability of analysis results depends on the quality of input. Lot of care has to be taken to provide the following inputs
q Load of each consumer
q Transformer load
q Power Factor(PF)
q Power & Energy flow at the Input buses on the network
q Actual voltage levels at the input bus
Analysis
After providing necessary inputs, the software can be asked to perform analysis for the following:
q Load flow study
q Short circuit analysis
q What if analysis
q Over loaded equipment analysis
q Network reconfiguration
q Switching optimization
q Load balancing
q Energy auditing
q HVDS
q Reconductoring
q Capacitor placement
q Express feeder proposal
q Protective device coordination
Output
q The output of the analysis will be given in a summary format / graphical view
q Based on the queries specific reports on voltage regulation, loss level, loading levels can be obtained
q Segregation of losses at various voltages and into categories
q Identification of causes leading to Higher Losses
q Estimation of benefits from various improvement options to choose the best option
Graphical Output
A series of graphical output examples depicting the analysis of a distribution network before and after carrying out some modifications is given. The graphical display provides information on improvement in voltages levels pre & post modifications.
GIS Based Growth Planning & Load Forecast Implications
What is the need?
For the Distribution system planning which involves siting of substations, routing of feeders and many other decisions relating to both locations and quantum of capacity additions, the forecast of Geographical locations as well as quantum of future load growth is necessary.
What is GIS based?
Load forecast of Geographical locations as well as quantum of future load growth can be easily made using GIS and also the planning of Distribution system like upgradation/strengthening can be performed accurately with the geographical, and network details with consumption history is available in the GIS.
Three step procedure for load forecast.
1. Trend Analysis - analysis of past trends of growth in electricity demand and energy consumption
2. System load forecast viz. Forecasts of load for the entire study area
3. Spatial or small area load forecast viz. Divide the utility service area into sufficiently large number of small areas and forecast for each small area
Trend analysis
Trends in electricity demand plays a significant role in the forecast of future demand if the area is already exposed to electrical power usage and past records are available.
Data required for Trend analysis
q Category wise number of services
q Connected load
q Energy consumption for the last 5 to 10 years, etc
The above parameters can be incorporated in GIS for Trend analysis
Growth rate of energy - year wise and cumulative growth rate of energy for the period
Share of electrical energy consumption among different sectors year wise and the average for the period
Energy consumption per service year wise and the average for the period
Growth rate of service connections year wise and cumulative growth rat for the period
Connected load per service connection year wise and the average during the period
System load forecast techniques
q Techniques Based on Extrapolation
Fitting a trend curve to the basic historical data, using method of least squares
q Techniques Based on Co-relation
Relates the system demand to various demographic and economic factors
q End use Method
Demand of each category of consumer is assessed and summed up to arrive at total consumption. Generally this method is adopted for distributionsystems.
End use method
The demand for energy is estimated for each category of consumption taking into account relevant parameters such as
q No. of consumers
q Connected load
q Annual rate of energy consumption per consumer
q Past trends, etc
q Peak demand is worked out from total consumption adopting appropriate load factors keeping in view the nature and composition of loads and considering the loss figures.
Estimation of Agricultural Consumption/Rural Load
Main factors contributing to load growth in this sector are:
q Potential for tapping ground water /lifting it from a flow of stream
q Development of other allied agricultural activities like horticulture, forestry, fishery and
q Potential for development of agro-based industries and ongoing programmes of other development agencies for boring of well and / of energisation of pump sets
Agricultural Consumption
Agricultural consumers are largely unmetered & a correct assessment of energy consumption is also very difficult
Agricultural consumption mainly depends on
q Number of Pumpsets
q Capacity of Pump set
q Number of working hours per day
The No. of Pumpsets and their capacity are grossly underestimated, as there are number of unauthorized Pumpsets and the capacity of the motor is increased due to depleting water table.
Agricultural Consumption
The number of working hours depends on:
q Area irrigated
q Types of crops grown
q Ground water level
q No. of crops grown/annum
q Yield of well
q Rainfall in the year
q Type of soil
q Seasonal requirement
q Availability of power supply
Methods to assess Agricultural Consumption
q Sampling
Avg. consumption per HP from sampling techniques
q Annual Load Factor
Avg. Load Factor x Total kW of pumpsets x 8760
q Consumption /irrigation/hectare as per studies by independent agencies
Consumption for one irrigation/ hectare x No. of irrigation/year x Total land under irrigation. Comparing with State Tubewell/Corporation Tubewell Consumption Data
Spatial load forecast
Forecast of Load and their Locations
Total area is divided into a number of small areas and the loads in each area are forecasted
q Constitution of small areas:
q Grid co-ordinate system - for urban areas
q Random area method - rural area
Objective of spatial load forecast is to allocate among the small areas the growth of demand or energy consumption/number of customers computed in system forecast for the total area
Planning Objective
Objective of strengthening and improvement of ST&D is
q To ensure quality and reliability of supply to consumers
q Bring down technical losses to an optimal value and
q Phase the system expansion to match the demand growth in the time horizon of the study
Planning Phillosophy
q Approach for Planning of distribution system should be based on:
q Delivering bulk supply of electricity as near to the load centres as possible
q Consumers affected due to outage to be few in the area, if at all it becomes inevitable
q Formation of ring circuit and radial circuit or combination of both, depending on the technical and economic requirement of the system to enhance reliability of power supply
Planning Criteria
q Voltage regulation
q Siting of Primary substation
q Capacities of Power & Distribution transformers
q Choice of conductor
q 11kV feeder design
q Selection of voltage vis a vis size of conductor
q Customer substation
Planning Criteria
q Power Factor
q Technical loss levels
q Max fault levels
q Harmonic distortion
q Sub-station layout
q Distribution automation.
GIS based planning
Upgradation of Sub-transmission & Distribution systems
Based on the Demand Growth, the planning for the upgradation of ST&D system should be performed
Sub-Transmission system requirement:
q Augmentation of sub-stations
q New Sub-stations
q Sub-transmission lines (new)
q Reconductoring of sub-transmission lines
Upgradation of Sub-transmission & Distribution systems
Distribution system requirement:
q Augmentation of Distribution sub-stations
q New 11 kV lines
q Reconductoring of 11 kV lines
q New Distribution sub stations
q Reconductoring of LT feeders
q New LT lines
Long term technology options
q Adoption of HVDS
q Standardization of construction practices and O&M procedures
q Adoption of Distribution Automations techniques
q Adoption of DSM measures
q Use of electronic meters with remote meter reading systems, prepayment meters, etc.
q Use of all aluminum alloy conductors, AB LT lines in theft prone area, XLPE cables
q Low loss transformers
q Ring main units, Automatic sectionalisers, autoreclosers, load break switches, etc
q Adoption of Management Information systems, Customer Relationship management systems, etc
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