Power grid modelling for GRID compliance study

• Main Author: Shah Dev Dikul
• Other Authors: Abhishek Ukil
• Format: Theses and Dissertations
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Electrical and electronic engineering
• Online Access: http://hdl.handle.net/10356/72601
• Institution: Nanyang Technological University

Distributed generation capacity is likely to rise over time, as the world’s focus is shifting towards a reliable, economical and efficient means of generating electricity. However, to ensure optimal safety and security of the electric power system, the power grid companies require the generating machines to follow certain technical specifications set by them in the form of “Grid Codes”. Contents of a grid code may vary from one country to another depending on the requirements of the energy utilities and hence the study of a generator’s connection requirement cannot be generalized. It is thus important to study the grid codes of various countries meticulously. This dissertation deals with the analysis of critical requirements of a synchronous generator’s connection requirements for two grid codes, namely German Grid code & Technical rules defined by Western Power Australia. Amongst all the requirements, low-voltage ride through (LVRT) and the active power recovery requirements are identified as the critical and the same has been studied in detail. LVRT refers to the capability of electric generators to stay connected to the power grid, even in periods of voltage dips. Subsequently, upon fault clearance, the recovery of active power should also be as quick as possible and it is also specified in the respective grid codes. However, an immediate increase of active power can cause voltage fluctuations and it should be dealt meticulously for the grid compliance matters. These are some of the most demanding requirements and hence it is important to analyze them during the modelling stage of the generator system. To study these effects in detail, a three-bus grid model having a diesel generator has been developed. Simulations for grid compliance of the generator considering Western Power Australia and German grid codes were performed using MATLAB/SIMULINK. For grid compliance studies, effects of different fault positions and grid conditions were assessed for different settings of active power output of the generator. It is observed that a generator operating at lower active power output is having better grid compliance characteristics for both LVRT and active power recovery. Flywheel and breaking resistor hardware solutions have also been proposed and implemented to improve the grid compliance of diesel generators with stringent grid codes such as Western Power Australia. Detailed observations of the simulations are presented and discussed.