Diagnosis and localization of fault for a neutral point clamped inverter in wind energy conversion system using artificial neural network technique

Introduction. To attain high efficiency and reliability in the field of clean energy conversion, power electronics play a significant role in a wide range of applications. More effort is being made to increase the dependability of power electronics systems. Purpose. In order to avoid any undesirable effects or disturbances that negatively affect the continuity of service in the field of energy production, this research provides a fault detection technique for insulated-gate bipolar transistor open-circuit faults in a three-level diode-clamped inverter of a wind energy conversion system predicated on a doubly-fed induction generator. The novelty of the suggested work ensures the regulation of power exchanged between the system and the grid without faults, advanced intelligence approaches based on a multilayer artificial neural network are used to discover and locate this type of defect; the database is based on the module and phase angle of three-phase stator currents of induction generators. The proposed methods are designed for the detection of one or two open-circuit faults in the power switches of the side converter of a doubly-fed induction generator in a wind energy conversion system. Methods. In the proposed detection method, only the three-phase stator current module and phase angle are used to identify the faulty switch. The primary goal of this fault diagnosis system is to effectively detect and locate failures in one or even more neutral point clamped inverter switches. Practical value. The performance of the controllers is evaluated under different operating conditions of the power system, and the reliability, feasibility, and effectiveness of the proposed fault detection have been verified under various open-switch fault conditions. The diagnostic approach is also robust to transient conditions posed by changes in load and speed. The proposed diagnostic technique's performance and effectiveness are both proven by simulation in the SimPower /Simulink® MATLAB environment.Вступ. Для досягнення високої ефективності та надійності у галузі чистого перетворення енергії силова електроніка відіграє важливу роль у широкому спектрі застосування. Докладаються зусилля для підвищення надійності систем силової електроніки. Мета. Щоб уникнути будь-яких небажаних ефектів або перешкод, що негативно впливають на безперервність роботи в галузі виробництва енергії, у цьому дослідженні пропонується методика виявлення несправностей біполярних транзисторів із ізольованим затвором при обриві ланцюга в трирівневому інверторі з діодною фіксацією системи перетворення енергії вітру, що ґрунтується на асинхронному генераторі з подвійним живленням. Новизна запропонованої роботи забезпечує регулювання потужності, що обмінюється між системою та мережею, без збоїв, для виявлення та локалізації цього типу дефекту використовуються передові інтелектуальні підходи, засновані на багатошаровій штучній нейронній мережі; база даних заснована на модулі та фазовому куті трифазних статорних струмів асинхронних генераторів. Запропоновані методи призначені для виявлення одного або двох обривів у силових ключах бокового перетворювача асинхронного генератора подвійного живлення у системі перетворення енергії вітру. Методи. У запропонованому методі виявлення для ідентифікації несправного вимикача використовуються тільки трифазний модуль струму статора і фазовий кут. Основною метою цієї системи діагностики несправностей є ефективне виявлення та локалізація відмов в одному або навіть кількох інверторних перемикачах з фіксованою нейтральною точкою. Практична цінність. Робочі характеристики контролерів оцінюються за різних умов роботи енергосистеми, а надійність, здійсненність та ефективність запропонованого виявлення несправностей були перевірені за різних умов відмови розімкнутого вимикача. Діагностичний підхід також стійкий до перехідних станів, спричинених змінами навантаження та швидкості. Продуктивність та ефективність запропонованого діагностичного методу підтверджені моделюванням у середовищі SimPower/Simulink® MATLAB

A modified neutral-point balancing space vector modulation technique for three-level neutral point clamped converters in high speed drives

This paper describes a high performance neutral point voltage balancing technique for a Neutral point clamped (NPC) Converter. Conventional neutral point voltage balancing methods do not function well under low power factor, low pulse ratio and near-unity modulation index operation conditions. These conditions are essentially dominant operation conditions for aircraft starter/generator systems. This paper introduces an alternative space vector modulation technique for three-level NPC converters in an aircraft starter generator system. The selection of voltage space vectors is optimized for high modulation index and low power factor operation. Disturbances caused by low pulse ratio is also compensated. The proposed method maintains neutral point voltage balance and ripple minimization over the full range of operating conditions. The paper also provides a detailed analysis into the sources of neutral point voltage imbalances and ripples in high speed drives with deep flux weakening. Simulation results obtained from a Simulink/PLECS model and experimental results obtained from a 45kVA, 32krpm aircraft starter generator test rig proves the proposed method eliminates the neutral point voltage imbalance and significantly reduces the neutral point voltage ripple

An Advanced Dual-Carrier-Based Multi-Optimized PWM Strategy of Three-Level Neutral-Point-Clamped Converters for More-Electric-Aircraft Applications

Since three-level neutral-point-clamped (3L-NPC) power generation units bring much competitiveness to the next-generation electric starter/generator (ESG) system for more-electric-aircraft (MEA) applications, the versatile multi-optimized pulse-width-modulation (PWM) becomes a key enabler to this technology. Regarding the mission profile of the state-of-art ESG, the operating points at the cruise feature a high modulation index and low power factor. This means that the neutral-point potential (NPP) fluctuation becomes severe. Besides, if switching states are not configured properly, not only could the lifetime of capacitors be threatened but also irreversible damage to bearing insulation occurs due to the common-mode voltage (CMV), followed by devastating effects on the reliability of other avionic facilities. Given the limitations of the 270VDC unipolar dc-bus structure, deep flux-weakening currents are constantly required for the high speed, resulting in more machine copper losses. To address these issues without any hardware-level efforts, an advanced PWM strategy with dual-carrier-based implementation is proposed in this article, which achieves boosted dc-link voltage utilization, CMV reduction and balanced NPP at the same time. Simulation results obtained from Simulink/PLECS and experimental results obtained from a 45 kW, 32 krpm ESG prototype system verify the effectiveness and feasibility of the proposed algorithm

Active Modulation Strategy for Capacitor Voltage Balancing of Three-Level Neutral-Point-Clamped Converters in High-Speed Drives

In this paper, the equivalent relationship between the nearest-three-virtual space vector (NTV2) and carrier-based pulse-width-modulation (CBPWM) scheme is established based on space vector coordinate for a three-level neutral-point-clamped (3L-NPC) converter. Moreover, to solve the neutral-point (NP) voltage imbalance problem of the studied 3L-NPC converter-fed high-speed drives, an active modulation strategy with the generalized bias-offset injection technique is proposed. Meanwhile, the excessive computational burden is significantly overcome by the fast calculation approach. The effectiveness of the proposed modulation algorithm is validated through both simulation and experimental results obtained from a 45 kW, 32 krpm aircraft electric starter/generator (ESG) prototype system

Hybrid Active Modulation Strategy for Three-Level Neutral-Point-Clamped Converters in High-Speed Aerospace Drives

In the aircraft electric starter/generator system, the three-level neutral-point-clamped converters play a crucial role in driving turbofan engines and delivering onboard electrical power. However, the conventional pulsewidth modulation (PWM) strategies face the challenge of capacitor voltage deviation, large common-mode voltage (CMV), and extra switching losses. Regarding the characteristics of the studied wide-speed range aerospace drives, the modulation scheme needs to be designed according to its operating conditions. To tackle the above demerits, a hybrid active modulation approach is, hence, proposed in this article. By the coordinate-based PWM, the nearest-three-vector is used in the startup process as the neutral-point (NP) voltage balance can be realized with fewer switching intervals; when the drives run in generation mode, an enhanced carrier-based virtual-space-vector modulation technique is involved, which aims to eliminate NP voltage fluctuation, suppress CMV, and simplify the modulation process. With the help of bias-offset injection in the time and voltage domain, capacitor voltages can be effectively kept at a balanced state even though the imbalance exists. The validity of the presented algorithm is proved by simulation and experimental results obtained from a 45 kW, 32 kr/min aircraft starter/generator test rig

Mild hybridisation of turboprop engine with high-power-density integrated electric drives

This paper shares with the aerospace community a case study of turboprop mild hybridisation using a recently developed integrated drive system in the University of Nottingham, UK, within the ACHIEVE project under EU H2020 CleanSky 2 program (project No. 737814). The developed drive system enables green taxiing of a turboprop aircraft while on the ground with its engine off, and as an electrical generator when the turboprop is in the air. The entire system is designed to be able to integrate within the power auxiliary gear box (PAGB) of a turboprop aircraft. Some of the key features of the developed system include a high-speed permanent magnet machine (up to 14,200rpm) with dual three-phase design, SiC-based high power density (11.8kW/L for the power converter, 35.3kW/L and 7.2kW/kg for the machine active parts), integrated cooling design for high-temperature operation (>130ºC ambient temperature), fault tolerance consideration with dual channel operation capabilities and sensorless control for entire operational conditions. This paper is giving an overview of the design process of the electrical machine, power converters, and its cooling of the entire drive. Numerical analysis (FEM and CFD) and some experimental results are presented to demonstrate the effectiveness and the desired performance of the developed integrated drive system