Hans-Peter Nee

Bio: Hans-Peter Nee is an academic researcher from Royal Institute of Technology. The author has contributed to research in topics: Silicon carbide & Converters. The author has an hindex of 48, co-authored 285 publications receiving 10055 citations. Previous affiliations of Hans-Peter Nee include Hitachi & Alstom.

Power-Synchronization Control of Grid-Connected Voltage-Source Converters

Abstract: In this paper, a novel control method of grid-connected voltage-source converters (VSCs) is proposed. The method can be generally applied for all grid-connected VSCs but may be of most importance in high-voltage dc (HVDC) applications. Different from the previous control methods, the proposed method utilizes the internal synchronization mechanism in ac systems, in principle, similar to the operation of a synchronous machine. By using this type of power-synchronization control, the VSC avoids the instability caused by a standard phase-locked loop in a weak AC-system connection. Moreover, a VSC terminal can give the weak ac system strong voltage support, just like a normal synchronous machine does. The control method is verified by both analytical models and time simulations.

On dynamics and voltage control of the Modular Multilevel Converter

Abstract: This paper discusses the impact of modulation on stability issues of the Modular Multilevel Converter (M2C) The main idea is to describe the operation of this converter system mathematically, and suggest a control method that offers stable operation in the whole operation range A possible approach is to as­sume a continuous model, where all the modules in each arm are represented by variable voltage sources, and as a result, all pulse width modulation effects are disregarded After simulating this model and test­ing different control methods, useful conclusions on the operation of the M2C have been extracted The control methods are then implemented on a model with discrete half-bridge modules, in order to compare the results and to validate the continuous model approach When assuring that this model functions as expected, the goal of this paper is to conclude into a self-stabilizing voltage controller A controller is proposed, which eliminates circulating currents between the phase legs and balances the arm voltages regardless of the imposed alteranting current

Model-based current control of AC machines using the internal model control method

Abstract: In the present paper, the internal model control (IMC) method is introduced and applied to AC machine current control. A permanent magnet synchronous machine is used as an example. It is shown that the IMC design is straightforward and the resulting controller is simple to implement. The controller parameters are expressed in the machine parameters and the desired closed-loop rise time. The extra cost of implementation compared to PI control is negligible. It is further shown that IMC is able to outperform PI control with as well as without decoupling with respect to dq variable interaction in the presence of parameter deviations.

Design, Control, and Application of Modular Multilevel Converters for HVDC Transmission Systems

Abstract: Design, Control and Application of Modular Multilevel Converters for HVDC Transmission Systems is a comprehensive guide to semiconductor technologies applicable for MMC design, component sizing con ...

Interconnection of Two Very Weak AC Systems by VSC-HVDC Links Using Power-Synchronization Control

Abstract: In this paper, voltage-source converter (VSC) based high-voltage dc (HVDC) transmission is investigated for interconnection of two very weak ac systems. By using the recently proposed power-synchronization control, the short-circuit capacities of the ac systems are no longer the limiting factors, but rather the load angles. For the analysis of the stability, the Jacobian transfer matrix concept has been introduced. The right-half plane (RHP) transmission zero of the ac Jacobian transfer matrix moves closer to the origin with larger load angles. The paper shows that, due to the bandwidth limitation imposed by the RHP zero on the direct-voltage control of the VSC, high dc-capacitance values are needed for such applications. In addition, the paper proposes a control structure particularly designed for weak-ac-system interconnections. As an example, it is shown that the proposed control structure enables a power transmission of 0.86 p.u. from a system with the short-circuit ratio (SCR) of 1.2 to a system with an SCR of 1.0. This should be compared to previous results for VSC based HVDC using vector current control. In this case, only 0.4 p.u. power transmission can be achieved for dc link where only one of the ac systems has an SCR of 1.0.

Operation, Control, and Applications of the Modular Multilevel Converter: A Review

Abstract: The modular multilevel converter (MMC) has been a subject of increasing importance for medium/high-power energy conversion systems. Over the past few years, significant research has been done to address the technical challenges associated with the operation and control of the MMC. In this paper, a general overview of the basics of operation of the MMC along with its control challenges are discussed, and a review of state-of-the-art control strategies and trends is presented. Finally, the applications of the MMC and their challenges are highlighted.

Overview of Dual-Active-Bridge Isolated Bidirectional DC–DC Converter for High-Frequency-Link Power-Conversion System

Abstract: High-frequency-link (HFL) power conversion systems (PCSs) are attracting more and more attentions in academia and industry for high power density, reduced weight, and low noise without compromising efficiency, cost, and reliability. In HFL PCSs, dual-active-bridge (DAB) isolated bidirectional dc-dc converter (IBDC) serves as the core circuit. This paper gives an overview of DAB-IBDC for HFL PCSs. First, the research necessity and development history are introduced. Second, the research subjects about basic characterization, control strategy, soft-switching solution and variant, as well as hardware design and optimization are reviewed and analyzed. On this basis, several typical application schemes of DAB-IBDC for HPL PCSs are presented in a worldwide scope. Finally, design recommendations and future trends are presented. As the core circuit of HFL PCSs, DAB-IBDC has wide prospects. The large-scale practical application of DAB-IBDC for HFL PCSs is expected with the recent advances in solid-state semiconductors, magnetic and capacitive materials, and microelectronic technologies.

Multi-level conversion : high voltage choppers and voltage-source inverters

Abstract: The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters and generalized to any number of switches.<>

Reduced Switching-Frequency Modulation and Circulating Current Suppression for Modular Multilevel Converters

Abstract: This paper describes a modified phase-shifted carrier-based pulsewidth-modulation (PSC-PWM) scheme for modular multilevel converters (MMC). In order to reduce the average device switching frequency, a reduced switching-frequency (RSF) voltage balancing algorithm is developed. This paper also proposes a circulating current suppressing controller (CCSC) to minimize the inner circulating current in an MMC. Based on the double line-frequency, negative-sequence rotational frame, the three-phase alternative circulating currents are decomposed into two dc components and are minimized by a pair of proportional integral controllers. Simulation results based on a detailed PSCAD/EMTDC model prove the effectiveness of the modified PSC-PWM method and the RSF voltage-balancing algorithm. The proposed CCSC not only eliminates the inner circulating current but also improves the quality of the converter ac output voltage. A simple loss evaluation demonstrates that the RSF voltage-balancing algorithm and the CCSC reduce the converter power losses.