A low loss modular multilevel voltage source converter for HVDC power transmission and reactive power compensation

2014 IEEE International Power Modulator and High Voltage Conference (IPMHVC)

Clare

et al. 2014

The Compact Linear Collider (CLIC) is an electron-positron collider under study at CERN with the aim to explore the next generation of high precision/high energy particles physics. The CLIC's drive beams will be accelerated by approximately 1300 klystrons, requiring highly efficient and controllable solid state capacitor discharge modulators. Capacitor charger specifications include the requirement to mask the pulsed effect of the load from the utility grid, ensure maximum power quality, control the derived DC voltage precisely (to maximize accuracy for the modulators being implemented), and achieve high efficiency and operability of the overall power system. This paper presents the work carried out on the power system interface for the CLIC facility. In particular it discusses the challenges on the utility interface and analysis of the grid interface converters with regards to required functionality, efficiency, and control methodologies. ABSTRACTThe Compact Linear Collider (CLIC) is an electronpositron collider under study at CERN with the aim to explore the next generation of high precision/high energy particles physics. The CLIC's drive beams will be accelerated by approximately 1300 klystrons, requiring highly efficient and controllable solid state capacitor discharge modulators. Capacitor charger specifications include the requirement to mask the pulsed effect of the load from the utility grid, ensure maximum power quality, control the derived DC voltage precisely (to maximize accuracy for the modulators being implemented), and achieve high efficiency and operability of the overall power system. This paper presents the work carried out on the power system interface for the CLIC facility. In particular it discusses the challenges on the utility interface and analysis of the grid interface converters with regards to required functionality, efficiency, and control methodologies.

Section: Power Electronicsmentioning

confidence: 99%

“…Supporting the dynamics of the pulsed capacitor discharge and low AC power fluctuation are the main objectives. Modular multi-level topologies are foreseen as the most suitable utility interface power converters for this application since they offer high efficiency, reliability and redundancy [4,5].…”

Section: Introductionmentioning

confidence: 99%

Optimal power system and grid interface design considerations for the CLICs klystron modulators

Jankovic

2014 IEEE International Power Modulator and High Voltage Conference (IPMHVC)

Clare

et al. 2014

“…Research into the performance of the converter in a balanced network is presented in [7,[26][27][28][29][30]. The authors of [31] investigated the operation of the converter with a depressed AC voltage by introducing voltage notches in the AC voltages which has an effect on the DC bus voltage similar to the staggered voltage operation of the converter chainlinks in [5].…”

Section: Introductionmentioning

confidence: 99%

“…Other advantages of the converter include high efficiency [28,31] and fewer devices as compared to a standard MMC. Therefore the running cost of the converter is expected to be significantly lower.…”

Section: Introductionmentioning

confidence: 99%

Operation of a hybrid modular multilevel converter during grid voltage unbalance

Amankwah

IET Generation, Transmission & Distribution

Clare

2016

The recently proposed parallel hybrid modular multilevel converter is considered to be a low loss, low component count converter with soft switching capability of the 'main' H-bridge. The converter has similar advantages to other emerging modular multilevel converter circuits being considered for HVDC power transmission and can be made compact which is desirable for offshore application. However, during ac network unbalance the individual 'chain-links' exchange unequal amounts of power with the grid which requires appropriate remedial action. This paper presents research into the performance of the converter and proposes a suitable control method that enables the converter to operate during grid voltage unbalance. The proposed control concept involves the use of asymmetric third harmonic voltage generation in the 'chain-links' of the converter to redistribute the power exchanged between the individual 'chain-links' and the grid. Mathematical analysis and simulation modelling with results are presented to support the work described.

“…Research into the performance of the converter in a balanced network is presented in [7,[9][10][11][12][13]. The converter uses a cascade of half bridge cells to produce a full wave rectified multilevel waveform for each phase according to (1) during balanced network operations according to (2).…”

Section: Introductionmentioning

confidence: 99%

Control of a hybrid modular multilevel converter during grid voltage unbalance

Amankwah

11th IET International Conference on AC and DC Power Transmission

Wheeler

et al. 2015

Self Cite

The recently proposed parallel hybrid modular multilevel converter is considered to be a low loss, low component count converter with soft switching capability of the 'main' bridge. The converter has similar advantages to other emerging modular multilevel converter circuits being considered for HVDC power transmission. However, during ac network unbalance the individual 'chain-links' exchange unequal amounts of power with the grid which requires appropriate remedial action. This paper presents research into the performance of the converter and proposes a suitable control method that enables the converter to operate during grid voltage unbalance. The proposed control concept involves the use of asymmetric third harmonic voltage generation in the 'chain-links' of the converter to redistribute the power exchanged between the individual 'chain-links' and the grid. Mathematical analysis and simulation modelling with results are presented to support the work described.