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Fault tolerant operation can significantly improve the reliability of a Modular Multilevel Converter (MMC), but the precondition is that a fast and accurate fault detection and localization method has been embedded into the MMC control system. This paper proposes a fault diagnosis method used in a distributed control architecture, which makes the local controllers capable of identifying the switching...
This paper introduces a new insertion index selection method to control a Back-to-Back Modular Multilevel Converter (MMC) laboratory platform. The test bench is based on a Power-Hardware-In-the-Loop (PHIL) setup constructed from two 6kVA, 3-phase, 10 cells per arm MMC systems connected in Back-to-Back configuration. The proposed insertion index selection method uses the arithmetic mean of available...
In this paper, a method to diagnose and identify the open-circuit faults of IGBT for a six-level hybrid inverter (6L-HI) is proposed, which is based on the signals of the inner device voltages, the flying capacitor voltages and the phase currents of the inverter. Since the flying capacitor voltage sensors and the output current sensors are already employed for the inverter operation, only one additional...
In this paper, a wireless power transmission with foreign-object detection (FOD) consideration is proposed. In the foreign-object detecting technique, a closed-loop feedback control is proposed by tracking the voltage and current of transmitting coil in order to signal the occurrence of a significant phase difference, anticipating preventing the system from potential risks. To validate the effectiveness...
As HVDC based on voltage source converter (VSC) technology has already reached 350 kVdc voltage level, this paper examines the feasibility of connecting four voltage source converter (VSC) modules, each rated at 200 kVdc, in series to form a pole of UHVDC rated at 800 kVdc. Due to the series connection layouts, the individual DC bus voltage inequality exists when power reversal occurs. A detailed...
This paper investigates the operation principle, modeling, and control of a hexagonal converter for grid connected photovoltaic (PV) systems. The hexagonal converter is composed of six conventional two-level voltage source converters (VSCs) in which each VSC module are connected to a string of PV modules. The equivalent circuit model of the proposed topology is first detailed in the abc reference...
A predictive control scheme for the third-harmonic injection two-stage matrix converter (3TSMC) under unbalanced input voltages is presented. The proposed scheme is designed to predict the future behavior of the third-harmonic injection current and load currents respectively for each valid switching state. The control scheme selects the state that minimizes the error between the predicted currents...
Under partial shading condition or imbalanced temperature distribution, the power-voltage characteristic curve of photovoltaic (PV) array exhibits complicated multiple peaks. Traditional maximum power point tracking (MPPT) method is usually easy to trap into local extreme power point. To solve this issue, this paper proposes a novel MPPT method using quantum-behaved particle swarm optimization (QPSO)...
The detection of the fundamental frequency and phase angle of the positive sequence grid voltages are utmost necessary for the proper operation of controlled active power converters, which require to operate stable and robust even during the presence of diverse power quality issues. There exist various utility grid synchronization and detection methods based on Phased-Locked Loop (PLL) techniques...
This paper presents a switching-based charger with a time division fast charging (TDFC) control to decrease circuit complexity and charging time for multiple batteries. Time division scheme can deliver a different energy amount to each battery to achieve battery voltage balance and remove the effect of the battery's parasitic resistor to prolong the charging time in constant current (CC) stage. To...
The sensitivity and the bandwidth of passive UHF radiofrequency identification (RFID) transponders are strongly affected by the power conversion efficiency and the input quality factor of the used analog front-end. In this work, we present two differential UHF RFID analog front-ends, considering particularly circuit implementations in a 40 nm low power CMOS technology. We discuss design aspects of...
This paper provides a novel voltage space vector modulation algorithm dedicated to the inverter fault-tolerant motor drive systems based on the four-switch inverter topology. The proposed technique ensures an accurate phase voltage modulation even under a DC-link voltage imbalance. Moreover, the capacitor voltages of the DC-link are leveled up so that the simultaneous motor drive operation is obtained...
This paper proposes an impedance-based active-filter additional control method for grid connected PWM-converters, by which a PWM-converter can help improve the voltage quality at a sensitive load bus (SLB) of a complex network with many distributed unbalanced loads and nonlinear loads. To realize the method, the information of the voltage to be compensated needs to be acquired and transferred to the...
Testing and verification of high-level and low-level control, modulation, fault handling and converter co-ordination for modular multilevel converters (MMCs) requires development of experimental prototype converters. In this paper, we provide a a complete overview of the MMC-based experimental prototype at UNSW Sydney (The University of New South Wales) including the structure of the sub-modules,...
The design of a digital state-space controller employing a deadbeat state observer is presented for uninterruptible power source (UPS) inverter applications with inductor-capacitor (L-C) filters. Conventionally, the inductor current and capacitor voltage values are utilized as the measured feedback variables for the controller, and the load current is either measured or estimated. In the proposed...
Lightning invaded over-voltage is the main cause of insulation fault of electric apparatus. To acquire the actual substation lightning invaded over-voltage, a monitoring system based on arrester valve divider is proposed in this paper. The working principle and advantages of the proposed monitoring system is analyzed firstly. And then, the actual overvoltage waveforms are presented, which are recorded...
This paper proposes an energy storage unit integrated dual input PV system with distributed maximum power point tracking (MPPT). Through applying a symmetrical configuration, the proposed PV system has a single stage structure to implement voltage boosting and inversion, which contributes to the advantages such as compact size and high power conversion efficiency. The design of the control strategy...
At present, the field of power factor corrected (PFC) rectifiers are very much matured. Typically a single phase PFC converter requires measurements from three independent sensors i.e. input voltage, input current and output voltage. By considering a need of farther compact and more flexible in terms of input to output voltage gain, a new UPF rectifier with two buck-boost converter operating in interleaved...
State Grid of China has constructed multiple ultra high-voltage direct current (UHVDC) projects in recent years. UHVDC projects like Ximeng-Taizhou are hierarchically connected to different AC systems at the receiving end. The high voltage and low voltage valve groups on the hierarchical side are connected to different AC systems, and different tap changer steps of transformers, measurement error,...
This paper proposes a modified sub-module voltage measurement technique for the PSC-PWM modulated modular multilevel converter (MMC) using less voltage sensors. With this technique, the sub-modules per arm are divided into several groups according to their respect carrier phase angles. This arrangement ensures that only one sensor is needed within each divided group. Therefore, the number of sensors...
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