Extension of power transmission capacity in MMC-based HVDC systems through dynamic temperature-dependent current limits

Gonçalves, Jorge; Rogers, Daniel; Liang, Jun

doi:10.1109/epe.2015.7309159

Cited by 5 publications

(8 citation statements)

References 11 publications

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“…Where is the nominal current of the system, ( ) is the nominal operating junction temperature of the semiconductor switch, and is the temperature droop constant and it denote the decrease in current limit per unit increase in temperature and is given by [17]:…”

Section: B Isolation Dab Control Blockmentioning

confidence: 99%

Overloading Scenario in Solid State Transformer

Kadandani

Dahidah

Ethni

et al. 2020

2020 11th International Renewable Energy Congress (IREC)

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Nowadays, solid state transformer (SST) is been considered as an alternative option in smart grid where additional ancillary services that cannot be provided by conventional line frequency transformer (LFT) are required. However, the power transmission capability of SST is limited to that of its semiconductor switches which are power electronics devices. As such SST needs a new way of dealing with overload. This paper presents an investigation into the overloading scenario in SST. The overloading is achieved by modifying the SST control algorithm to include a current limiting controller that modulates the output current as a function of junction temperature.

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Section: B Isolation Dab Control Blockmentioning

confidence: 99%

Overloading Scenario in Solid State Transformer

Kadandani

Dahidah

Ethni

et al. 2020

2020 11th International Renewable Energy Congress (IREC)

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“…The proposed submodule temperature control loop regulates SM capacitor voltages to prevent SM temperature from reaching dangerous values and must therefore avoid temperature overshoots. Using the principle of bandwidth separation between the cascaded loops and neglecting constant disturbances, the open-loop transfer function G (s) of the system can be defined as follows: (10) where the gain K c is defined as follows:…”

Section: B Stability Of Submodule Temperature Regulationmentioning

confidence: 99%

“…In HVdc systems, where dozens or hundreds of SMs per 587 arm are employed, the switching frequency of each individual 588 device will be very low, reducing the proportion of switching losses in the overall semiconductor losses. This is investigated through the reduction of the switching frequency of 500 Hz of the MMC with ten SMs per arm from [10], utilized for the results in Fig. 10(a), to 150 Hz.…”

Section: Operation At Low Switching Frequency 586mentioning

confidence: 99%

“…Previous works [8], [9] have addressed system-level thermal control strategies for two-and three-level converters. Although some of these works have been extended for MMCs [10], thermal management strategies operating at the SM-level have not yet been proposed. It has also been shown that it is possible to achieve significantly different temperatures between the SMs of an arm during normal operation due to the load conditions [11], resulting in unequal current and loss distribution between the dies in the semiconductor modules.…”

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confidence: 99%

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Submodule Temperature Regulation and Balancing in Modular Multilevel Converters

Gonçalves

Rogers

Liang

2018

IEEE Trans. Ind. Electron.

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In modular multilevel converters (MMCs), tem-5 perature control of semiconductor devices in the submod-6 ules (SMs) is a key factor for the safe and reliable opera-7 tion. Under normal operation, significant temperature differ-8 ences can exist between SMs due to, for example, aging of 9 semiconductor modules and module parameter mismatch. 10 This paper presents a method for achieving SM thermal bal-11 ancing by controlling the capacitor voltage of each SM in an 12 arm, while maintaining the sum of the SM capacitor voltages 13 at a constant value in order to regulate the dc-link voltage. 14 The proposed temperature balancing strategy is validated 15 using an experimental MMC setup with three SMs, where an 16 increase in the thermal resistance to ambient of one or more 17 SM semiconductors is created by restricting coolant flow to 18 simulate a partial failure in the cooling system. Increases 19 in the thermal resistance by 21% and 42%, corresponding 20 to temperature increases of 5 and 10 • C, respectively, are 21 managed by three SMs, using a capacitor voltage margin of 22 60%. 23 Index Terms-Capacitor voltage balancing, electronics 24 cooling, modular multilevel converter (MMC), power semi-25 conductor devices, temperature control, thermal manage-26 ment of electronics. 27 I. INTRODUCTION 28 M ODULAR multilevel converters (MMCs) are a widely 29 used voltage source converter (VSC) topology for 30 medium voltage drives [1] and high-voltage direct current 31 (HVdc) transmission systems [2]. For industrial applications [3], 32 dozens or even hundreds of submodules (SMs), each support-33 ing a few kilovolts, are employed to produce a quasi-sinusoidal 34 voltage waveform from a dc-link. This SM-based structure dis-35 tributes the stored energy across the SM capacitors instead of 36

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“…In [7]- [9] the influence of converter temperature dynamics on the achievable overload were neglected. Overload capability of MMC-based HVDC systems considering the temperature dynamics within the converter has arguably only been discussed in [10] and [11]. However, in [11], simplified temperature dynamics were used and implications on the converter design were not addressed.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Overload Capability of VSC HVDC Interconnections for Frequency Support

Sanz

Judge

Spallarossa

et al. 2017

IEEE Trans. Energy Convers.

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In future power systems reduced overall inertia caused by an increased dominance of asynchronous generation and interconnections would make frequency control particularly challenging. As the number and power rating of Voltage Source Converter (VSC) HVDC systems increases, network service provision would be expected from such systems and to do so would require overload capacity to be included in the converter specifications. This paper studies the provision of frequency services from Modular Multilevel Converter (MMC)-based VSC HVDC interconnections using temperature-constrained overload capability. Overload of the MMC-based HVDC system is achieved through controlled circulating currents, at the expense of higher losses, and subject to a control scheme which dynamically limits the overload available in order to keep the semiconductor junction temperatures within operational limits. Two frequency control schemes that use the obtained overload capacity to provide frequency response during emergency conditions are investigated. The controllers' performance is demonstrated in the context of the future Great Britain transmission grid through a reduced equivalent test system. Simulation results show that even modest temperature margins which allow overload of MMCbased HVDC systems for a few seconds are effective as a primary frequency reserve and also reduce the loss of infeed requirements of such interconnections.

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Extension of power transmission capacity in MMC-based HVDC systems through dynamic temperature-dependent current limits

Cited by 5 publications

References 11 publications

Overloading Scenario in Solid State Transformer

Overloading Scenario in Solid State Transformer

Submodule Temperature Regulation and Balancing in Modular Multilevel Converters

Dynamic Overload Capability of VSC HVDC Interconnections for Frequency Support

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