COMPUTER AIDED POWER SYSTEM ANALYSIS, Schemes and Mind Maps of Computer-Aided Power System Analysis

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Computer Aided Power System

Analysis

Sangeeta Modi Department of Electrical and Electronics Engineering

Economic Load Dispatch

Sangeeta Modi Department of Electrical and Electronics Engineering

Economic Load Dispatch Economic load dispatch refers to the determination of the optimal scheduling of the generating units to minimize the operating cost of generators for the given load demand while satisfying equality and inequality constraints

Economic Load Dispatch CONSTRAINTS IN ECONOMIC LOAD DISPATCH :

• EQUALITY CONSTRAINTS Basic Load flow equations for P and Q are the equality constraints
• INEQUALITY CONSTRAINTS

Economic Load Dispatch CONSTRAINTS IN ECONOMIC LOAD DISPATCH INEQUALITY CONSTRAINTS : It is essential that the following parameters at various nodes should vary within the certain limits.

• Voltage constraints
• Generator constraints
• Running Spare Capacity Constraints
• Transmission Line Constraint
• Transformer setting constraints
• Dynamic Constraints

Economic Load Dispatch CONSTRAINTS IN ECONOMIC LOAD DISPATCH INEQUALITY CONSTRAINTS : Voltage constraints Vmin ≤ V ≤ Vmax δmin ≤ δ ≤ δmax Generator constraints KVA loading of generator should not exceed prescribed value Pmin ≤ P ≤ Pmax Qmin ≤ Q ≤ Qmax

Economic Load Dispatch Transformer tap set For autotransformer tap ‘t’ should be between 0 & 1 For two winding transformer – between 0 & k

Economic Load Dispatch Transformer tap set For autotransformer tap ‘t’ should be between 0 & 1 For two winding transformer – between 0 & k

Economic Load Dispatch

Economic Load Dispatch Incremental Fuel Cost Cost Function and input-output curve is given as :

Economic Load Dispatch Condition for Economic load dispatch - When losses are neglected All the plants must operate at equal incremental production cost. This is also known as coordination equation

Economic Load Dispatch – Observe the difference in data

Economic Load Dispatch Find ELD scheduling of two units. C1 = 100+2P1+0.005P1^ C2 = 200+2P2+0.01P2^ Where P 1 and P2 are in MW. Total load is 450 MW. Find ELD scheduling of two units. Assume - Losses to be neglected Solution ( Hint) : Losses – Neglected , Constraints – Not Given P1+P2 = 450 ----(1) IFC 1 = IFC2 ----Condition for ELD P1 = 300 MW and P2=150 MW IFC1= 5 Rs/ MWh and IFC2= 5 Rs/ MWh

Economic Load Dispatch – losses are considered Optimal load Dispatch problem including transmission losses The auxiliary function using Lagrange multiplier is written as :