A Commutation Failure Prediction and Mitigation Method

Line-commutated converter based high-voltage direct-current (LCC-HVDC) transmission systems are prone to subsequent commutation failure (SCF), which consequently leads to the forced blocking of HVDC links, affecting the operation of the power system. An accurate commutation failure (CF) identification is fairly vital to the prevention of SCF. However, the existing CF identification methods cause CF misjudge or detection lag, which can limit the effect of SCF mitigation strategy. In addition, earlier approaches to suppress SCF do not clarify the key factor that determines the evolution of extinction angle during system recovery and neglect the influence. Hence, this paper firstly analyzes the normal commutation process and CF feature based on the evolution topology of converter valve conduction in detail. Secondly, the energy in the leakage inductance of converter transformer is presented to characterize the commutation state of the valves. Then a CF identification method is proposed utilizing the leakage inductance energy. Thirdly, taking the key variable which is crucial to the tendency of extinction angle during the recovery process into account, a fault current limiting strategy for SCF mitigation is put forward. Compared with the original methods, the proposed methods have a better performance in CF identification and mitigation in terms of detection accuracy and mitigation effect. Finally, case study on PSCAD/EMTDC validates the proposed methods.

Section: B Verification Of Improved Cf Identification Methodsmentioning

confidence: 99%

Section: Implementation Of Scf Mitigation Strategymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improved Identification Method and Fault Current Limiting Strategy for Commutation Failure in LCC-HVDC

Liu

Lin

Zhong

et al. 2022

“…VSC-HVDC transmission systems have outstanding advantages in the flexible integration of renewable energy and decoupling control of active and reactive power [1] - [3]. Meanwhile, there is no commutation failure compared with the traditional HVDC technology [4]. However, VSC-HVDC grids usually use overhead lines, which have a high probability of line faults.…”

Section: Introductionmentioning

confidence: 99%

A Similarity Comparison Based Pilot Protection Scheme for VSC-HVDC Grids Considering Fault Current Limiting Strategy

Chen¹,

He²,

Li³

et al. 2023

In the voltage source converter based high-voltage direct current (VSC-HVDC) grids, fast and reliable protections are the key technologies. The traditional protection schemes are easily affected by fault resistance, line distributed capacitance, etc. Meanwhile, the influence of fault current limiting strategy (FCLS) has not been fully considered. In this paper, the fault characteristics under FCLS and the feasibility of traditional travelling wave protections are analyzed. To improve the reliability and sensibility, a similarity comparison based pilot protection scheme is proposed, which focuses on the relationship between the fault characteristics and the state of the protected transmission line, with the establishment of a precise frequencydependent transmission line model. The criteria based on the similarity comparison calculated by cross-wavelet can identify the fault effectively. Meanwhile, the protection scheme can also endure the influence of error synchronization. Finally, the protection performance is verified in the PSCAD/EMTDC under different fault conditions.

“…In addition, the advancing firing angle (FA) control is proposed to improve the control performance of the constant extinction angle (CEA) controller. The CEA controller can be classified into two categories: one is the measured-type controller such as CIGRE control [13] and SIEMENS control [14], [15], and the other is the predictedtype controller such as ABB control [15], [16] and the proposed methods in [17]- [20].…”

Section: Introductionmentioning

confidence: 99%

Commutation Failure Mitigation Method Based on Imaginary Commutation Process

Zhou

Xia

Hong

et al. 2022

Self Cite

The commutation failure (CF) mitigation effectiveness is normally restricted by the delay of extinction angle (EA) measurement or the errors of existing prediction methods for EA or firing angle (FA). For this purpose, this paper proposes a CF mitigation method based on the imaginary commutation process. For each sample point, an imaginary commutation process is constructed to simulate the actual commutation process. Then, the imaginary EA is calculated by comparing the imaginary supply voltage-time area and the imaginary demand voltage-time area, which can update the imaginary EA earlier than the measured EA. In addition, the proposed method considers the impacts of commutation voltage variation, DC current variation, and phase angle shift of commutation voltage on the commutation process, which can ensure a more accurate EA calculation. Moreover, the DC current prediction is proposed to improve the CF mitigation performance under the single-phase AC faults. Finally, the simulation results based on CIGRE model prove that the proposed method has a good performance in CF mitigation.