IMPROVED EVALUATION OF ATC WITH LINE-THERMAL LIMITS AND BUS-VOLTAGE QUALITY CONSTRAINTS

39 Pages·01.101 MB·English

by  Dr. Eng. Mohamed EL-Shimy (Ain Shams University)

IMPROVED EVALUATION OF ATC WITH
LINE-THERMAL LIMITS
AND BUS-VOLTAGE QUALITY CONSTRAINTS
Journal: Scientific Bulletin - Faculty of Engineering - Ain
Shams Uni. Vol. 40, No. 1, March 31, 2005, pp. 619-630
Author(s): M EL-Shimy

Paper 1 1
Definition of ATC
 In this paper available transfer capability
(ATC) indicates how much inter-area
power transfers can be increased without
violation of
 any of transmission lines thermal limits
and
 any of bus-voltage quality constraints
of the entire system network.
Paper 1 2
Importance of ATC Evaluation
 Inaccurate identification of ATC can yield to
 Transmission congestion, and
 Degradation of system security and
reliability.
 ATC information can help
 ISO to determine the validity of bidding results in an
open access deregulated electricity market when the
speed of calculation of ATC is sufficient.
 the power market participants to place bids
strategically when congestion happens.
Paper 1 3
Importance of ATC Evaluation
(Cont.)
 ATC calculations are useful for evaluating the
ability of an interconnected power system to
 remain secure following generation and
transmission outages and also to
 determine the amount of lost generation
that can be replaced by potential
reserves and limiting constraints in each
circumstances
Paper 1 4
ATC Evaluation Requirements
 A good ATC evaluation method is
characterized by:
 Fast computation speed, and
 High accuracy

Paper 1 5
Drawbacks of Previous
Methods
 Previous methods used:
 DC models based methods  Fast calculation
speed but low accuracy.
 CPF based methods  high accuracy, but low
calculation speed.
 Linearized AC models based methods  fair.
 All previous methods did not consider bus
voltage magnitude limits  related to PQ,
VAR compensation requirements … etc
Paper 1 6
Paper Objectives
 Evaluation of ATC based on linearized AC model of
the system network.
 It is assumed that the system is operating at
normal-state at base-case operating conditions.
 The proposed method consider both
 Line thermal limits, and
 Bus-voltage magnitude constraints
 A transaction allowance/rejection criteria is given.
Paper 1 7
PROBLEM FORMULATION
Paper 1 8
Problem Formulation
 The overall procedure for ATC calculation is divided
into two stages:
 Stage # 1:
 Determination of PTDFs and
 Calculation of ATC limited by transmission lines thermal
limits (ATCTL) i.e. thermally limited ATC.
 Stage # 2:
 Determination of PTVS factors and
 Calculation of voltage limited ATC (ATC VL).
 Based on ATCTL and ATCVL the net ATC is calculated.
Paper 1 9
Problem Formulation (Cont.)
 The allowance and rejection of a
given transaction is based on its ATC
value.
 A given transaction is allowed if its value
is < ATC and
 A given transaction is rejected or limited
to ATC value if its value is > ATC.
Paper 1 10