load flow studies.docx
TRANSCRIPT
-
7/27/2019 Load Flow Studies.docx
1/3
Load Flow Studies
1. IntroductionThe load flow study reveals the steady state performance of the power system. Through the study
potential unacceptable voltage conditions and overloading of transmission network elements can be
identified.
2. Inputs for the StudyDemand in each grid substation can be obtained from National Power and Energy Demand Forecast,
published by CEB. The generation dispatch has to be worked out with reference to the Long Term
Generation Plan, also published by the CEB. NCRE Dispatch can be worked out based on the trial
scenario mentioned in the chapter 13.
The studies have to be done considering power system model with current and future
developments. Long Term Transmission Expansion Plan contains the data relevant to the
transmission system development and Long Term Generation Plan Specifies the expansion of
generation capacity. Specifically the steady state impact of two key proposals that would
significantly change the economic absorption capability of intermittent sources in Sri Lanka:
proposed India-Sri Lanka grid interconnection and the prospects of developing pumped storage
capacity have to be considered.
3. OutputsIdentification of steady state constraining factors when NCRE is integrated according to the each
scenario can be done.
Potential Technical Constraints
Unacceptable voltage conditions
Overloading of transmission Network Equipment
Depending on the technical limitations defining the capacity of each key renewable energy resource
that can safely absorb to the existing national grid can be found.
Proposing necessary adjustments to the grid in order to meet the identified constrains has to be
done in such a way that the power is delivered within the operating limits of the equipment in a
continuous manner without any wide spread failures. This will be an iterative process.
These capacities can be further evaluated over economical and any physical limitations in specific
geographical area where potential has been indicated in studies/scenarios proposed by the Master
Plan team.
-
7/27/2019 Load Flow Studies.docx
2/3
4. Criteria to be fallowed Voltage criteria
The voltage criterion defines the permitted voltage deviation at any live bus bar of the network
under normal operating conditions as given in table
: Allowable voltage variations
Bus bar voltage Allowable voltage variation (%)
Normal
operating
condition
Single
contingency
condition
220 kV 5% -10% to +5%
132kV 10% 10%
33kV - ???????????????
Thermal criteria
The design thermal criterion limits the loading of any transmission network element, in order to
avoid overheating due to overload. The loading of elements should not exceed their rated thermal
loading values for steady state conditions.
Security criteria
The performance of the transmission system under contingency situation is taken into consideration
in the security criteria. The adopted contingency level for the planning purposes is N-1, i.e. outage of
any one element of the transmission system at a time.
5. System AnalysisLoad flow studies should be performed on the model considering
1. Normal operation conditions
2. N-1 contingency conditions
3. Two generation scenarios
a. Hydro Maximum
b. Thermal Maximum
4. Three Loading Conditions
a. Day Peak (11.00 h)
b. Night Peak (19.30 h)
c. Off Peak (03,00 h)
Above 3 and 4 can be summarized in a table as bellow.
-
7/27/2019 Load Flow Studies.docx
3/3
Scenario LoadGeneration
Thermal Hydro
TMNP Night Peak Max Balance
TMDP Day Peak Max BalanceHMNP Night Peak Balance Max
HMDP Day Peak Balance Max
OP Off Peak Partial Partial
5. Five NCRE generation scenarios
These NCRE scenarios are explained in detail in chapter 13.
Description
Abbreviation
used
Energy Share
of NCRE-based
in this papergeneration inthe grid by2032
Very aggressive, wind dominant VAWD 30%
Aggressive, wind and biomass dominant AWBD 25%
Aggressive with solar, wind and biomass ASWB 25%
Aggressive, mixed scenario AMIX 20%
Early Solar, Aggressive wind and biomass ESWB 25%
6. Three loading conditions
a. Working Day (WD)
b. Week End Holiday (WE)
c. Public holiday (HD)
All together there are 75 scenarios to be considered.
TMNP TMDP HMNP HMDP OP
WD WE HD WD WE HD WD WE HD WD WE HD WD WE HDVAWD 1 6 11 16 21 26 31 36 41 46 51 56 61 66 71
AWBD 2 7 12 17 22 27 32 37 42 47 52 57 62 67 72
ASWB 3 8 13 18 23 28 33 38 43 48 53 58 63 68 73
AMIX 4 9 14 19 24 29 34 39 44 49 54 59 64 69 74
ESWB 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75