Şebekeye bağlı üç fazlı sic tabanlı hibrit anpc evirici yapısının kontrolü ve tasarımı
Control and design of the grid connected three-phase sic based hybrid npc inverter
Yazar: İSLAM DELİBAŞ
Danışman: DOÇ. DR. MURAT YILMAZ ; DR. ÖĞR. ÜYESİ DENİZ YILDIRIM ; DOÇ. DR. ATİYE HÜLYA OBDAN
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Elektrik Ana Bilim Dalı / Elektrik Bilim Dalı
Derece: Yüksek Lisans, 2022
Konu: Elektrik ve Elektronik Mühendisliği = Electrical and Electronics Engineering ; Enerji = Energy
Dizin: Eviriciler = Inverters ; Güç sistemleri = Power systems ; Yumuşak anahtarlamalı inverter = Soft switching inverter

Özet:
Enerji sistemlerinde kalitenin önemi son yıllarda gittikçe artan bir kavram haline
gelmiştir. Güç sistemlerinde oluşan kirlilik sorunlarının çoğu, güç elektroniği
ekipmanlarının doğrusal olmayan karakteristiklerinden ve yüksek anahtarlama
frekanslarından kaynaklanmaktadır. Güç kalitesi sorunları, hassas yarı iletken
elemanların daha da hassaslaşması, var olan filtreleme ve kompanzasyon
yöntemlerinin neden olduğu maliyet artışı nedeniyle zamanla daha da artmaya devam
edecektir. Güç kalitesinin iyileştirilmesi, yarı iletken ve diğer doğrusal olmayan
cihazların son zamanlarda artması nedeniyle başlıca araştırma konularından biri haline
dönüşmüştür. Herhangi bir enerji kaynağının güç kalitesi, harmonik seviyesi vs. gibi
etkenler uluslararası kuruluşlar tarafından tanımlanan belirli limitler çerçevesinde
sınırlandırılmaktadır. Bu limitlerin sağlanabilmesi için farklı harmonik kompanzasyon
yöntemlerine başvurulmaktadır. Bu limitlere uyulması, performans ve işletme
ekonomisi için büyük önem taşımaktadır. Harmonik kompanzasyon ürünleri modern
enerji dağıtım sistemlerinde yaygın olarak kullanılmaktadır. Bu ürünlerin
geliştirilmesi için evirici tabanlı sistemlere ihtiyaç duyulmaktadır. Üç seviyeli evirici
tabanlı geliştirilen aktif harmonik filtreler (AHF), diğer harmonik kompanzasyon
filtrelerinden daha iyi performansa sahip güç filtrelerinden biridir.
Üç seviyeli şebeke bağlantılı tasarlanan eviriciler kaynak ve yük dengesizlikleri
altında güçlü performans sağlayan doğru tasarlanmış bir kontrol algoritmasına ihtiyaç
duymaktadırlar. Kontrol yöntemleri, Gerilim Kaynaklı Eviricileri (VSI) tetiklemek
için gerekli referans akımlarının üretilmesinde kullanılmaktadırlar. Bu nedenle,
sistemin kararlılığı büyük ölçüde kullanılan kontrol algoritmasına bağlıdır.
Bu tezde, kullanılan üç seviyeli SiC-ANPC tabanlı evirici sistemleri için geniş bir
literatür araştırması yapılmıştır. Bu literatür araştırması içinde; güncel uygulamalarda
kullanılan farklı evirici topolojileri ve kontrol teknikleri detaylandırılmıştır. AHF
sistemlerinde kullanılmak üzere tasarlanan 3L SiC-ANPC sistemi için farklı kontrol
yöntemleri analiz edilmiş ve tartışılmıştır. Ayrıca, farklı evirici topolojileriyle PLECS
ve Matlab/Simulink ortamında simülasyonlar gerçekleştirilmiştir. Bu evirici
topolojilerinin verimlilik ve maliyet karşılaştırmaları yapılmış ve bu tezde
sunulmuştur. Prototip haline getirme sürecinde yapılan PCB tasarımları Altium
Designer ile gerçekleştirilmiştir. Prototip çalışması gerçekleştirilen evirici sisteminin
test sonuçları tezde sunulmuştur.Bu tezde tasarlanan üç seviyeli şebeke bağlantılı
evirici yapısında kullanılan SiC tabanlı evirici yapısı ile piyasada üretilen evirici
yapılarının 2 katı bant genişliğine sahip bir evirici yapısı tasarlanmıştır. Aynı zamanda
%98 üzerinde verimlilik sağlanmıştır. Piyasada üretilen evirici yapılarının birçoğu Si-
IGBT veya Si-MOSFET tabanlı tasarlanmıştır. SiC tabanlı tasarlanan ürünlerin bant
genişliği ve verimlilikleri düşük kalmaktadır. Bu tezde tasarlanan evirici yapısı ve
FPGA tabanlı kontrol ile literatürde benzeri çalışması olmayan bir evirici tasarımı kazandırılmıştır. 5kHz kontrol bant genişliğine, 40kHz anahtarlama frekansına ve bu
anahtarlama frekansında çalışabilmesi için 80kHz örnekleme frekansına sahip bir
evirici yapısı tasarlanmıştır.

Abstract:
Nowadays, the worldwide electrical infrastructure is undergoing extensive change due
to increasing electrical energy demand, environmental problems, energy policies and
rapid technological development, especially in the field of power electronics. This
change is a process towards the realization of the smart grid, a vision of the future
power system where the flow of electrical power and communication between
producer and consumer are to becoming bidirectional.
The development and integration of distributed generation (DG) is an another
important aspect of this change, where the centralized power generation plants are to
be complemented by a higher penetration of low-scale generation plants at the
distribution level. In recent years, the worldwide installed power, based on distributed
energy resources (DER), such as grid-connected photovoltaic power plants and wind
turbines, has grown exponentially. As a result, the total generation capacity as well as
the penetration of renewable environmental friendly energy resources are increasing.
Incorporating these resources into microgrids that can be operated in grid-connected
mode or islanded mode seems to be a promising way to achieve intelligent application
of these resources in the energy system. However, this development is causing the grid
structure to become ever more complex.
Also, given the intermittent nature of many renewable energy sources and their
performance depending on meteorological and geographical conditions, total energy
production tends to be more variable. In addition, grid stability, power quality and
reliability can be compromised due to the penetration, technology and control of these
distributed energy sources. Traditionally, these challenges have been met by using
large rotating mass synchronous generators in large, conventional power plants. Now
it also needs to be solved at the distribution level to realize the great potential
associated with the smart grid paradigm and renewable distributed energy sources.
The key to overcoming these challenges relates to the control and coordination of the
individual power generation units, that is, the control of the respective power
electronics converters. This topic has received great attention in research, and the field
of power electronics converters and their control has experienced great development
in recent years. Numerous proven solutions have been proposed in the literature, all
about converter technologies, topologies and control algorithms for grid
synchronization, current and voltage control, anti-island strategies, and more, all to
improve the performance and operation of distributed energy sources. . The most basic
task of these controllers is to inject appropriate AC current and voltage signals into the
external utility grid. In recent years, resonance type controllers have received much
attention in research due to their ability to manage this task when also used in a
stationary reference frame.

The importance of quality in energy systems has become an increasing concept in
recent years. Most of the pollution problems in power systems are due to the non-linear
characteristics of power electronic equipment and high switching frequencies. Power
quality issues will continue to increase over time due to the sensitive equipment will
be more sensitive and the cost increase caused by existing filtering and compensation
methods. Improving power quality has become one of the main research topics due to
the recent increase in semiconductor and other non-linear devices. The power quality
of any source and harmonic factor are limited by the some indexes defined by
international organizations. In order to achieve these limits, different harmonic
compensation methods are used. Compliance with these limits has great importance
for performance and operating economy. Harmonic compensation products are widely
used in modern energy distribution systems. Active harmonic filters (AHF), developed
based on active 3L-NPC inverters, are one of the power filters with better performance
than other harmonic compensation filters.
3L-SiC-NPC based systems need a well-designed control algorithm that provides
strong performance under source and load imbalances. Control methods are used to
generate the required reference currents to trigger Voltage Source Inverters (VSI).
Therefore, the compensation of harmonics largely depends on the control algorithm
used. For any shunt AHF system, there are many ways to control the VSI.
Silicon carbide (SiC) devices have excellent performance, such as higher switching
frequency and lower switching loss compared with traditional silicon (Si) devices. The
application of SiC devices in inverters can achieve higher efficiency and power
density. In recent years, the production process of SiC devices has become more
mature, but the cost is still several times that of traditional Si devices. In order to
balance cost and efficiency, replacing only some of the Si devices with SiC devices in
a topology is a better choice.
Neutral point clamped (NPC) topology is a common three-level topology, and it is
widely used in medium and high-power photovoltaic inverters. In this three-level NPC
inverter, the voltage stress on each power device is only half of the bus voltage. Its
output voltage harmonic content is lower compared with the two-level inverters.
However, the NPC inverter has the problem of uneven power loss distribution over the
power devices. Uneven loss distribution will increase the design requirements for the
heat sink, resulting in larger volume of the heat sink, which is not conducive to
improving the power density of the inverter. To solve this problem, the active neutral
point clamped (ANPC) three-level topology is the best option. The ANPC topology
replaces the clamp diodes in the NPC topology with active switches. Thus, the PWM
(Pulse Width Modulation) control of the ANPC topology is more flexible. When the
ANPC inverter outputs zero state, there are multiple redundant loops to choose from.
The Digital Signal Processors that are the sequential processing device in which
characteristics and programming are known. The Field Programming gate arrays is the
architecture and reconfigurable digital logic devices, which contain a variety of
programmable logic blocks called logic elements which can be configurable using a
VHDL (Very High Speed Integrated Circuit Hardware Description Language). The
advantages of FPGA over sequential hardware of DSPs are flexible memory
architecture, wide parallelism, and deep pipelining. FPGA show great potential for
control applications, power electronics and real time hardware emulation, applications
such as motor control, active power filters, multilevel inverters.

FPGAs are an efficient hardware for rapid prototyping. Its functions are complex
enough to mplement more than glue logic. As the logic capacity of the FPGAs
increases, synthesis for PGA is becoming more important. One solution to designing
large designs efficiently is to use VHDL synthesis.
In recently, electrical power device technology have allowed for the generation of
current in power electronics applications and systems, in order to increase devices
switching frequency. However, as frequency increased problems are arises such as
time to perform function and calculate the control algorithm. FPGA digital controllers
are increasing attention to the control of power inverters.
In this thesis, an extensive literature search was carried out for AHF systems using 3L
SiC-NPC inverter. In this literature research; inverter topologies and control
techniques used in current applications are detailed. Different control methods are
analyzed and discussed for the 3L-SiC-NPC inverter. In addition, different inverter
topologies simulated in the PLECS environment. The efficiency and cost comparisons
of these inverter topologies are made and presented in this thesis. PCB design was
made with Altium Desginer software and the test results were presented in the thesis.
The three-level grid-connected SiC-ANPC inverter structure designed in this thesis
has twice the bandwidth of the inverter structures produced in the market. The
efficiency of this inverter is over 98%. Most of the inverter structures produced in the
market are designed based on Si-IGBT or Si-MOSFET. Bandwidth and efficiency of
products designed based on SiC remain low. An inverter structure has been designed
with a control bandwidth of 5kHz, a switching frequency of 40kHz and a sampling
frequency of 80kHz to operate at this switching frequency. In this way, for the first
time, an inverter structure that works with these features has been introduced to the
literature.