Thesis
MÉTODO SECUENCIAL PARA ESTUDIOS DE FLUJOS DE POTENCIA EN SISTEMAS DE CA CON ENLACES DE CD
Autor
VALENZUELA SALAZAR, JOSÉ LUIS
Institución
Resumen
High Voltage Direct Current (HVDC) transmission lines are elements that are
currently used in electric power systems to solve important technical problems like:
the interconnection of asynchronous systems, power transmission using submarine
cables, transmission of large amounts of power over very long distances and the
interconnection of renewable energy power plants, among others. This is the reason
it is necessary to know the basics of HVDC transmission lines operation, application
and behavior.
This work describes the basics of operation and performance of naturally
commutated and voltage source converter HVDC transmission lines. Besides, it
implements static models of both types of HVDC lines, which are adequate for power
flow and power system stability studies using static models. This allows assessing the
effect of these transmission system elements in an alternative current power system.
In order to validate the HVDC static models, they were implemented in an AC power
flow program coded in FORTRAN 90 using the sequential method, and the results of
this program were compared to the ones reported in references and other obtained by
PSSE and PSAT commercial programs, considering different test power systems.
The sequential method considered in this work to simulate naturally commutated
HVDC lines has been recently proposed by Chinese researchers and works
adequately, since the DC system converges in all cases to values of the model
variables inside their permissible operating limits. In a similar way, the sequential
method used to solve the VSC lines models provides suitable results in all the test
cases considered.
Since any standard test cases or models are actually available for AC-DC power flow
studies, some differences were found when comparing the results of the program
developed in this work, with the ones provided by commercial simulation programs.
These differences were due to variations in the solution method and the structure of
the HVDC line models, which are not clearly reported in the case of the commercial
programs. However, results obtained with the program developed in this work are
considered as acceptable, because in all cases the operating conditions found by the
program were inside the permissible operating region of the HVDC lines.