Limitations of voltage source converter in weak ac networks from voltage stability point of view

“…Furthermore, they are also beneficial to the healthy operation of the protection devices owing to the large currents generated during faults [19]. Additionally, SCs are also capable of improving system voltage and frequency stability and increasing the maximum active power transfer capability between the HVDC converter and the interconnected transmission network [20][21][22]. Conventionally, the size of the SC is only selected from the system and converter operation perspectives, but the quantification from the protection point has not been fully considered.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of HVDC system's impact and quantification of synchronous compensation for distance protection

Liu

Hong

Tzelepis

et al. 2022

IET Renewable Power Gen

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This paper presents a comprehensive evaluation of the HVDC system's impact on distance protection via systematic and realistic experimental tests, along with theoretical analysis of the root causes of the identified compromised protection performance. A methodology for quantifying the impact of Synchronous Compensation (SC) in supporting the distance protection operation is also established. In this work, the performance of two widely used physical distance protection relays have been evaluated using a realistic Hardware'In'the'Loop (HIL) testing environment, where a total of 480 cases have been tested under a wide range of system scenarios. Representative cases with compromised protection performance are selected, where issues of under/over'reach, faulted phase selection and impedance measurement are identified and analysed. Furthermore, a method for quantifying the required SC level to address the under/over'reach issues resulting from HVDC systems is presented. The method establishes the relationship between the angle difference of the two'end fault current infeeds of the protected line and the SC level. Based on this relationship, the required SC capacity to constrain the angle difference within a targeted limit can be estimated, which offers a useful tool for system operators to appropriately size the SC's capacity with additional valuable insights from the distance protection perspective.

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“…As a result, the performance of GFLs is highly dependent on the strength of the connected network and GFLs could start experiencing operational issues, e.g. loss of synchronisation [3][4], resonant problems [5] and limited active power transfer [6], in weak systems, e.g., when Short Circuit Ratio (SCR) < 3 [7].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of grid-forming converter's impact on distance protection performance

et al. 2022

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Motivated by the net-zero carbon emission target, the GB transmission system has seen a massive increase in the amount of Converter Based Resources (CBRs). Grid-Forming Converters (GFMs) have attracted significant interests for supporting the future system operability with high penetration of renewables due to their various more desirable properties compared with Grid-Following Converters (GFLs), e.g., stronger capability to operate in weak grids. Recent research work has found that Fault-Ride Through (FRT) strategies of CBRs have significant impact on the distance protection performance, and comprised protection operation was observed when synchronous generation sources were replaced with CBRs. However, existing research work has mainly focused on the impact of the GFLs' FRT on distance protection, while the impact of GFMs, which could have very different FRT strategies, has not been comprehensively investigated. In this paper, a GFM with two typically used FRT implementations, i.e., the current control based FRT and the virtual impedance based FRT, is developed in the Real-Time Digital Simulator (RTDS) and the impact of the two FRT methods on distance protection is investigated for both balanced and unbalanced fault conditions. By comparing the relay performance with two FRT strategies, it is found that the distance protection appears to have better performance in terms of faulty phase selection, accurate impedance measurement and impedance measurement stability when the virtual impedance-based FRT is adopted by the GFM.

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Limitations of voltage source converter in weak ac networks from voltage stability point of view

Cited by 11 publications

References 10 publications

Customized converter for cost-effective and DC-fault resilient HVDC Grids

Customized converter for cost-effective and DC-fault resilient HVDC Grids

Evaluation of HVDC system's impact and quantification of synchronous compensation for distance protection

Evaluation of grid-forming converter's impact on distance protection performance

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