Thermal analysis of a submodule for modular multilevel converters

Ma, Cong; Avenas, Yvan; Miscevic, Marc; Wang, M.-X; Mitova, Radoslava; Lavieville, J.-P.; Lasserre, Philippe

doi:10.1109/apec.2014.6803682

Cited by 10 publications

(5 citation statements)

References 7 publications

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“…In addition to the four restrictions mentioned previously, the junction temperature limits of the IGBT devices must be respected when designing VSCs. The maximum specified operating temperature for high power IGBT modules is usually 125 o C. This is typically not a concern in MMCs due to the high efficiency which results in relatively low junction temperatures [22], [24]. In [10] however, it was found that utilizing circulating currents to achieve an overload capability of 30% causes approximately a 20 o C increase in the steadystate junction temperatures, when compared against the case where the converter is operating at rated power.…”

Section: MMC Overload Capabilitymentioning

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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Section: MMC Overload Capabilitymentioning

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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“…Each switching loss in S 1 and S 2 is given by (27) and (28) respectively. Similarly, each recovery loss in D 1 and D 2 is given by (29) and (30) respectively.…”

Section: Calculation Of Switching Loss and Recovery Lossmentioning

confidence: 99%

“…Second, in terms of the heat sink design, the loss analysis and the breakdown of the semiconductor losses have been reported in the chopper cell type MMC (27) (28) . Besides, the evaluation of the heat sink volume in IGBTs with the voltage rating of which varies from 600 V to 6.5 kV has been also discussed (29) .…”

Section: Introductionmentioning

confidence: 99%

Design Guidelines of Circuit Parameters for Modular Multilevel Converter with H-bridge Cell

Nakanishi

Itoh

2017

IEEJ Journal IA

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This paper presents theoretical formulae for circuit parameter design as design guidelines in a step-down rectifier in a power system connected to a 6.6-kV AC power grid, where a modular multilevel converter (MMC) is applied. In particular, this paper focuses on the design of heat sinks, capacitors, and arm inductors. In addition, the worst case for each component design is shown as the first step of the converter design. First, the formula for the ripple current in the electrolytic capacitor is derived in order to evaluate the capacitor lifetime. Second, the formulae for the semiconductor losses are clarified on the basis of the analysis of the arm current. Third, the formula for the ripple current in the arm inductor is derived on the basis of the ripple current model of a chopper circuit. Finally, all formulae are verified by experiments with a miniature model. It is confirmed that theoretical values from formulae agree with the measured values with the errors lower than 12%.

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“…In that case, the switching frequency of that SM will be lower, since the charging and discharging processes of the SM with a high value of C i is slower, while the other SMs will be penalized to be inserted and bypassed more often, as it is summarized in Table II. However, the unequal switching operation has a significant impact only on the switching losses of the S l , which is usually the device with the highest loading (at unity power factor) [7]- [10]. The turn-on and the turn-off energy of the lower IGBT S l are much higher than the other IGBT from the SM.…”

Section: Thermal Unbalance Related To the Switching Lossesmentioning

confidence: 99%

“…In contrast, the balancing of power losses and junction temperature of the power devices from the SMs are usually not taken in consideration. In MMC applications, the power losses distribution of the devices from the same SM is usually unequal, depending on the operating condition which is mainly determined by the power factor [7]- [10]. For the half-bridge type SM, the most unequal device loading occurs when the MMC operates at unity power factor, which is a typical operating condition for the HVDC applications [11].…”

Section: Introductionmentioning

confidence: 99%