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In order to reduce the size of high-voltage flying capacitors in the five-level hybrid-clamped inverter, an improved modulation strategy based on phase-shifted PWM (PSPWM) is proposed in this paper. The four carrier waves are redistributed and the charge/discharge time of the high voltage capacitor can be largely reduced. The only disadvantage of this PWM scheme is that the harmonic characteristic...
In small-signal stability studies, various stability criteria have been proposed based on impedance or admittance norms to assess the stability of power systems. Controlling these norms can drag a system from a stable to an unstable operating condition. Therefore, finding a control variable that has a direct linear relation with these norms will facilitate the utilisation of data-driven control principles...
Due to the three-phase-to-three-leg direct matrix converter (3 × 3 MC) cannot be achieved with unbalanced load, then the three-phase-to-four-leg direct matrix converter (3 × 4 MC) is introduced. A novel modulation strategy is proposed to ensure the capability of 3 × 4 MC with arbitrary loads, which is development by using fixed voltage vectors and one zero vector. Considering the harm of common-mode...
Prototyping and proper testing of the electrical control unit of more electric aircraft (MEA) under various load profiles and fault conditions is necessary to ensure the performance of the controller. In order to solve the problems such as complicated operation, high experiment cost and long development period in aircraft power system traditional test method, this paper presents a semi-physical real-time...
Offshore wind farms tend to become bigger and far from the onshore point of connection. The developers and the system operators are facing a number of technical, economical, and environmental challenges in transmitting the bulk power developed at these offshore wind farms over long distances. In this Chapter, some of these issues are discussed, giving emphasis to the basic system requirements along...
This paper presents a high-speed pipeline architecture for squarer-accumulator (SQAC). The proposed design integrates squarer into multiplier-accumulator (MAC), producing the SQAC, which is utilized widely in signal processing field. The proposed architecture takes advantage of carry-save technique in the accumulation, and utilizes a novel feedback scheme. These ideas could also be applied to improve...
This paper proposes a grid-connection control strategy for doubly fed induction generator (DFIG) wind power systems based on direct virtual stator active and reactive power control. The proposed control strategy, named as Direct Virtual Power Control (DVPC), is achieved without proportional- integral (PI) regulator. It requires grid voltages, rotor currents, and rotor position information only. Using...
Deep neural networks (DNNs) have been widely applied in speech recognition and enhancement. In this paper we present some experiments using deep rectifier neural networks for speech denoising. Rectified linear units (ReLUs) can make a sparse connection between hidden layers. We analyze the usage of regularization coefficient during training to encourage more sparseness. This method further improves...
This paper proposed four stability improvement methods by source-side PWM rectifier for More Electric Aircrafts (MEAs). These stabilization methods are based on injecting compensation signals into the control loop of the source-side PWM rectifier which can omit remote sensor and compensation signal of each load. Besides, they overcome the drawback that load-side active damping methods do harm to load...
This paper investigates DC network partition and alternative DC fault protection strategy for Multi-terminal HVDC (MTDC) system. Fast acting DC Circuit Breakers (DCCBs) or fault blocking DC-DC converters can be configured at strategic locations to allow the entire MTDC system to be operated interconnected but partitioned into islanded DC network zones following faults. In case of any DC fault event,...
Computer planning and simulation of power systems requires system components to be represented mathematically. A method for building a dynamic phasor model of an Interline Dynamic Voltage Restorer (IDVR) is presented, and the resulting model is tested in a simple radial distribution system. Mathematical analysis is carried out for each individual component of the IDVR as modular models, which are...
Four-level hybrid-clamped (4L-HC) Inverter is a newly proposed topology which is suitable for high-performance medium-voltage power conversions. In order to improve the power density and reduce the harmonics, silicon carbide (SiC)-based devices can be used to improve the switching frequency. Thus, the capacitance of flying capacitors and voltage harmonics both can be reduced. This paper gives a detailed...
This paper proposes a novel active stabilization method based on reshaping the output impedance of the source-side PWM rectifier for More Electric Aircraft (MEA) power system. A nonlinear compensation signal is injected into AC voltage command of PWM rectifier to adding a virtual resistor paralleled with DC bus capacitor. Thus, the instability caused by constant power loads (CPLs) can be neutralized...
DC grid technology is one of the effective methods for collecting, transmitting and accommodating large-scale renewable energy over long-distance. Voltage source converter (VSC) based DC grid technology has become a preferred technical scheme because of its inherent advantages, such as flexible bi-directional DC power control capability. However, VSC based DC grid is also facing many operation control...
Five-level hybrid-clamped (5L-HC) inverter is a newly proposed topology which is suitable for high-performance medium-voltage drives. This paper presents a capacitor voltage balancing strategy for a 5L-HC inverter, including the voltage balancing of DC-link capacitors and flying capacitors. Classic phase-shifted PWM is used to control this converter and a mean value model of flying capacitor and neutral...
Hexverter is a recently proposed direct AC/AC modular multilevel converter (MMC). It features significant advantages for low-frequency drives compared to traditional MMC in back-to-back configuration. This paper presents a novel branch energy control method based on the injection of optimized circulating current and neutral-point voltage. It can effectively balance the energy stored in the six branches...
Four-level hybrid-clamped (4L-HC) converter is a newly proposed topology which is suitable for high-performance medium-voltage drives. Zero-sequence voltage (ZSV) is commonly used to balance the DC-link capacitor voltages of this topology and then the common-mode voltage (CMV) is also affected. This paper proposes a CMV reduction method for a back-to-back 4L-HC converter. The relationship of CMV and...
This paper proposes a new power supply system with multi-winding high frequency transformer for spacecraft. This structure drives loads of various voltage levels. It can provide a bi-directional power interface for battery clusters and realize electric isolation. Energy management strategies are proposed to improve efficiency and balance the power flow between sources and loads of different voltage...
Four-level hybrid-clamped (4L-HC) inverter is a newly proposed topology which is suitable for high-performance medium-voltage drives. This paper proposes a multi-objective optimization strategy for this 4L-HC inverter. The central DC-link capacitor and flying capacitor voltages are regulated by a modified phase-shifted PWM. The upper and lower capacitor voltages are balanced by zero-sequence voltage...
A flying capacitor based n-level non-isolated DC-DC converter is researched in this paper. The converter features reduced flying capacitors, compact structure, adjustable output voltage and high-voltage high-power ability. Basic operating principle was analyzed and a mean value model is derived. A dual-loop capacitor voltage balancing method for n-level structure is proposed. A seven-level prototype...
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