UWE Bristol Engineering showcase 2015

Ahmed Baraka
BEng (Hons) Electronic Engineering
Project Supervisor
Dr Hassan Nouri
STATCOM ​Inverter Switching Techniques: Investigation Using
MATLAB/Simulink
1. Overview
Static synchronous compensator (STATCOM) allows full utilization of existing power generation and transmission facilities. DC/AC inverter is a key component of
the STATCOM device. The inverter takes a DC voltage from a battery, a solar panel or any DC storage devices as input, and converts it into an AC voltage output.
This conversion is globally useful especially in places where the electrical infrastructure is not well-developed, since it provides a reliable mechanism to power
up AC appliances like electronic medical instruments in case of system failure or brownouts. This research focuses on investigating various Pulse Width
Modulation (PWM) switching schemes used for STATCOM inverter.
2. Single phase DC/AC inverter
MATLAB/Simulink has been used to design the building block for Sinusoidal PWM (SPWM). Signals, generated by SPWM drive the DC/AC inverter. As a
results, the inverter produces an output current, which is only distorted by 0.54%. This means that most of the energy stored in batteries, or solar panels
will be transformed into a desirable form with minimum losses, thus, increasing the efficiency of the inverter.
Project summary
The main aim of this project is to investigate and
compare different Pulse Width Modulation (PWM)
switching techniques for the purpose of identifying
the total harmonics distortion (THD) of the output
current waveform. The technique with the least THD
is to be used to study the performance of STATCOM.
Project Objectives
• To investigate various available switching
techniques used for STATCOM inverters.
• To simulate available switching schemes on a
multilevel, single phase and three phase inverter
using MATLAB/Simulink.
• To demonstrate the phase shifting properties of
the generated waveform by studying the
performance of STATCOM.
3. STATCOM Performance
Ideally, the voltage level at the customer end needs to be maintained at a certain level, regardless of any changes to the nature of the load. However, the load
bus bar faces variations in voltage level, when new loads are connected to the grid. The two main loads are: inductive loads, which cause the voltage at the
customer end to drop down, and capacitive loads, which cause the voltage at the customer end to go up. This problem is overcome by connecting the
STATCOM device to the system to act as a guard, which keeps the voltage maintained regardless of the nature of the load.
3.1 Inductive loads
3.2 Capacitive loads
Project Conclusion
• Upon simulation and investigation, sinusoidal
PWM has proven to be a very practical and
reliable switching technique.
• On a small scale, sinusoidal PWM can be used to
drive inverters to transform the continuous
current produced by the photovoltaic cells into
alternating current, ready to be directly absorbed
into the electricity distribution grid.
• On a large scale, the sinusoidal PWM inverter can
be used to design a closed loop control system
that compensates the flow of reactive power in
existing systems, thus, stabilising the voltage
level.