Geri Dön

Rms modeling of grid-formingpower electronics for renewableenergy power plant integration andclassical power system stabilitystudies

Başlık çevirisi mevcut değil.

PDF İndir

  1. Tez No: 721618
  2. Yazar: İBRAHİM KÜÇÜK
  3. Danışmanlar: DR. FİLİPE MİGUEL FARİA DA SİLVA
  4. Tez Türü: Yüksek Lisans
  5. Konular: Enerji, Energy
  6. Anahtar Kelimeler: Belirtilmemiş.
  7. Yıl: 2020
  8. Dil: İngilizce
  9. Üniversite: Aalborg Universitet
  10. Enstitü: Yurtdışı Enstitü
  11. Ana Bilim Dalı: Belirtilmemiş.
  12. Bilim Dalı: Belirtilmemiş.
  13. Sayfa Sayısı: 92

Özet

The share of the renewable energy sources (RESs) in electrical power system is continuously rising. Comparing to classical synchronous generators (SGs), RESs mostly operate with a maximum power point tracker algorithm and they act as a power source. RESs are mostly connected to grid with a power electronic interface. For this operation, it is a conventional solution to follow the existing grid, by grid-following control strategies. However, power systems are becoming weaker as the share of RESs increases and synchronous generators (SGs) are decommissioned. In the future, operation of RESs should adapt to be more than a simple power source. One proposed control strategy is grid-forming control, which is utilized by power converters to form an AC voltage and frequency in an electrical system. It is a control strategy which has been mostly studied for microgrid operations. For this project, the main objective is to build a RMS model of grid-forming (GF) converter for classical power system stability studies. Theories and trends regarding grid-forming converters and electrical power system are introduced through the report. In the introduction Chapter, recent trends in the electrical power system and the overview of the report and projects are provided. Recent regulations show that transmission system operators (TSOs) are imposing some control functions to renewable energy power plants (REPPs) for frequency and voltage support. Today's REPPs have grid-following control strategies, and they provide voltage and frequency support by a higher-level control which changes the operational active and reactive power set-points of the power plant. However, grid-forming control strategies can be used to support the voltage and frequency of the grid without any higher-level control. In Chapter two, the importance of SGs from power system stability point of view is highlighted and grid-forming control strategy is introduced as a promising method for future power system applications. A SG is a rotating voltage source, and its rotation is heavily dependent on its implemented droop characteristic. Similarly, a GF control has its own voltage and frequency set-points, and its electrical frequency can be adjusted in relation with its loading with a proper droop control. Therefore, a GF converter can be operated like a SG in a power system, and it can perform load sharing with other generation units with droop control. This ability to control a GF converter with droop controls makes it a convenient control strategy for power system applications. The motivation in RMS modelling is also introduced in this Chapter. TSOs perform both short- and long-term studies for many purposes such as analyses, planning and operation of power systems. RMS models and simulations have provided reliable results and minimized the computational burden until now for classical power system stability analyses. RMS analysis are still likely to be used for the years to come because EMT models are more complex and detailed which increases the computational burden. It would take a significant development in the system to shift to EMT analysis. The reliability of RMS simulations should be re-evaluated for a power system where it is dominated by power electronic interfaced generation units. vii WPS4-1050 In Chapter 3, the modelling of various elements used in the system are introduced. A simple power system is modelled with one external grid and one GF converter in PowerFactory. A REPP is used as a power source for the GF converter, and it is connected to the GF converter with a DC link. A shunt capacitor and a battery energy storage system (BESS) is implemented to DC bus of the GF converter. The GF converter is controlled by a cascaded voltage and current controller. The reference signals of voltage and frequency for the controller are provided by droop controls of the GF converter. The dedicated controls, block diagrams and important parameters of the previously mentioned elements in the system are introduced through the Chapter. Additionally, two adaptive droop control methods are introduced, which can provide frequency regulation for power systems. One method proposes shifting the frequency droop curve, and the other proposes changing the slope of the droop curve. In Chapter 4, case studies are presented. The first study investigates the behaviour of the GF converter where the effect of the external grid on power flow is minimized by implementing a vertical droop curve. A large load relative to the total rating of the system is switched in to make a dynamic change in the system, and to observe the response of the GF converter. This case study shows that the DC bus voltage of the GF converter is strongly dependent to the power outputs of the GF converter and REPP. The GF converter acts a voltage source, and when there is a load change in the system, the GF converter responses to the demand and immediately delivers the power. However, the REPP cannot deliver the same power to the GF converter at the same time, and this leads to a discharge in the DC link capacitor, and a voltage drop consequently. This case study shows that the GF converter works as a voltage source and it tends to deliver or draw reactive power to form its reference voltage. In the second case, the previously mentioned two adaptive droop control methods are implemented to the first case, where GF converter is dominant. The results show that both methods can support the system frequency and it moves back to its nominal value in the simulated ideal scenario. In the third case, a BESS is applied to the DC bus of the GF converter to support the DC voltage stability. The first case is used as base study and it is observed that the power contribution of battery during the voltage drop supports the voltage recovery. The maximum voltage drop and recovery time becomes lower. In the last case, a realistic scenario is introduced. The effect of the external grid was minimized in the previous cases by implementing a vertical droop curve. The external grid is applied a proper droop curve for this case study. Also, in the second case study, the adaptive droop controls are simulated in an ideal scenario. For this case study, some control constrains are activated for adaptive droop control. As a result of the adjustments, the GF converter and external grid shares the load, when the same amount of load with previous studies is switched in. It is observed that the change in the loading in the GF converter is lower comparing to the previous cases thanks to the load sharing based on droop controls. As the loading is lower, voltage drop is also lower than the previous cases. After the load switching, adaptive droop control is also automatically activated based on the drop in the frequency. A frequency support is observed by the activation, however, it is not able to restore the system frequency back to its nominal due to the applied constrains. From the simulation scenarios and the results of the designed RMS model of GF converter, it can be said that a GF converter can be operated like a SG in the future power system. viii With droop control implementation, it can operate in parallel with other generation units and successfully share the load. Additionally, extra control function such as the introduced adaptive droop control can be implemented in the future to support system stability. However, there are also challenges in operation of a GF converter such as DC link voltage stability, reactive power flow and rate of change of frequency. A battery storage system can be used to support DC link voltage. Any potential overloading problem based on reactive power flow of GF converter may be solved by implementing an adaptive voltage droop curve, similar to the adaptive droop curve implemented in this study for frequency. And as last, the rate of change of frequency can be control by a virtual inertia implementation. These challenges should be investigated in detail by further studies. A generic RMS model of GF converter is built in this study utilizing the PWM converter model in DIgSILENT PowerFactory. A cascaded voltage and current controller, which is the main control strategy for GF converters, is applied via DSL models to the converter. Voltage and frequency droop controls are also implemented to control the inputs of the converter. The GF converter controller can be exported and used for other RMS studies and it can be easily adapted to EMT analysis. The complete GF system, including the DC link capacitor, BESS and RES can be used for a power system level studies. These studies may include fluctuating or constant power source, different system events and different configuration of GF converter size, RES size and BESS size. Utilizing the introduced model and performing several studies by varying the configurations, needs of a GF converter operation can be analysed in terms of its power source, storage, parallel operation with other units or against different system event. The results from these studies can be evaluated by TSOs to determine the requirements of GF systems

Özet (Çeviri)

The share of the renewable energy sources (RESs) in electrical power system is continuously increasing. As a result, the conventional power plants, which mostly utilize large synchronous generators (SGs), are taken out from the operation and this leads to power system stability concerns. The conventional grid-following control strategies for RESs do not contribute to the stability. On the other hand, grid-forming (GF) controls acts as a voltage source in a system, and can perform an operation similar to SGs. In this study an RMS model of GF converter is built. The GF converter model is implemented to a simple power system and fed by a renewable energy source. The results showed that a GF converter can operate like a SG and it can perform load sharing based on its implemented droop curve. In addition, two adaptive droop control methods are introduced for frequency control in the power system. A battery storage system is proposed to support DC voltage during immediate power demands. The study is performed in DIgSILENT PowerFactory

Benzer Tezler

  1. Tez No

    507859

    Use of equivalent single porosity medium and automated lumped fluid composition in naturally fractured gas condensate reservoir simulations

    Doğal çatlaklı gaz kondensat rezervuarlarında eşdeğer tek gözenekli ortam ve otomatik toplu akışkan kompozisyonu simülasyonu kullanımı

    MEHMET CİHAN ERTÜRK

    Doktora

    İngilizce

    İngilizce

    2018

    Petrol ve Doğal Gaz MühendisliğiOrta Doğu Teknik Üniversitesi

    Petrol ve Doğal Gaz Mühendisliği Ana Bilim Dalı

    DOÇ. DR. ÇAĞLAR SINAYUÇ

  2. Tez No

    354321

    Design and implementation of a 1kw single phase grid tie inverter

    1 kw tek fazlı şebeke bağlantılı evirici tasarımı ve uygulaması

    OĞUZ ŞİMŞEK

    Yüksek Lisans

    İngilizce

    İngilizce

    2013

    Elektrik ve Elektronik MühendisliğiÇankaya Üniversitesi

    Elektronik ve Haberleşme Mühendisliği Ana Bilim Dalı

    DOÇ. DR. KLAUS WERNER SCHMIDT

    DOÇ. DR. MEHMET TİMUR AYDEMİR

  3. Tez No

    100803

    Kıyıboyu katı madde modelleriyle Doğu Karadeniz bölgesinde kıyı çizgisi değişimlerinin incelenmesi

    Investigation of the shorline change at the black sea region with longshore sediment transport models

    MUSTAFA ŞAŞAL

    Doktora

    Türkçe

    Türkçe

    2000

    İnşaat Mühendisliğiİstanbul Teknik Üniversitesi

    PROF.DR. NECATİ AĞIRALİOĞLU

  4. Tez No

    865214

    Elazığ - Sivrice ve Gezin civarının yeraltı yapısının gravite verileri kullanılarak modellenmesi

    Modelling of the subsurface structures of Elazığ - Sivrice and Gezin region by using gravity data

    NEDİM GÖKHAN AYDIN

    Doktora

    Türkçe

    Türkçe

    2024

    Jeofizik Mühendisliğiİstanbul Teknik Üniversitesi

    Jeofizik Mühendisliği Ana Bilim Dalı

    PROF. DR. TURGAY İŞSEVEN

  5. Tez No

    456237

    Busbar enerji dağıtım hatlarının geniş bant PLC kanal modellemesi ve başarım analizi

    Broadband PLC channel modeling and performance analysis of busbar energy distribution systems

    ZEYNEP HASIRCI

    Doktora

    Türkçe

    Türkçe

    2017

    Elektrik ve Elektronik MühendisliğiKaradeniz Teknik Üniversitesi

    Elektrik-Elektronik Mühendisliği Ana Bilim Dalı

    PROF. DR. İSMAİL HAKKI ÇAVDAR

Geri Dön