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Assessment of reliability indices is important when availability and unavailability of the system or systems or components or group of components are to be assessed. There are various reliability indexes which are very important for overall performance of any complex engineering system. Reliability block diagram modeling is required to be formulated for evaluating different essential and important reliability parameters of any complex engineering system. In view of above, in this paper, reliability block diagram modeling of HVDC converter station is represented and formulated. The schematic diagram of the HVDC converter station is available in literature and based on that schematic diagram the modeling of HVDC converter station is formulated in this paper. After the reliability block diagram modeling of HVDC converter station, the mean time to failure (MTTF) of each and every components of HVDC converter station are also evaluated and represented in the result and discussion section. The reliability of each and every component of the HVDC converter station is evaluated and expressed in result section. Assessment of unavailability is also obtained and shown in result section. [ABSTRACT FROM AUTHOR]

This paper introduces a new idea of energy efficiency evaluation of high voltage direct current (HVDC) converter based on deep neural networks. This paper analyzes the leading operating indicators and finds the main influencing factors in constructing the energy-saving hands of each converter table. Then this paper uses the deep neural network method to establish the converter table's energy efficiency model. The deep neural network for energy efficiency evaluation of the converter table is obtained. In this paper, PSCAD/EMTDC was used for simulation to evaluate the energy-saving effect. The research shows that the method of energy efficiency evaluation based on deep neural networks is feasible.

Hybrid DC circuit breakers (DCBs) have recently been used to break short-circuit fault currents to ensure safety in flexible DC transmission projects. However, electromagnetic transients from DCB operation can interfere with the secondary equipment and cause malfunctions. In this paper, the bipolar short-circuit test, which is the first short-circuit test for DC transmission line in flexible DC project in the world, has been carried out in the 200 kV HVDC converter station equipped with two hybrid DCBs. The transient magnetic field near the secondary equipment in the DCB hall were measured, and its characteristics were discussed. Furthermore, the relationships among the space magnetic field, the short-circuit current and the action of the power electronic equipment in the DCB were also analyzed The main findings are as follows. During the bipolar short-circuit process, the maximum space magnetic field intensity near the secondary device is 109 A/m, and the maximum rising rate of the magnetic field waveform is about 350 A/m/ms. The magnetic field strength reached its peak value at the moment when the DCB was blocked, as well as the short-circuit current. It can be indicated that the DCB can cut off the short-circuit fault current accurately and reliably. The results can provide reference for the immunity evaluation and anti-interference protection of secondary equipment, and its optimal arrangement in the DCB hall.

DC grounding fault is a typical fault for HVDC system. In order to obtain smoother, faster, and more secure transient process, the DC protection block strategy is used to remove and isolate the converter to prevent the accident enlargement and reduce the impact on devices and power grid when the grounding fault is detected. Two main strategies are commonly taken in this situation: the X block for not >±500 kV and the S block for ±800 kV. There is no specific principle on the strategy choosing for ±1100 kV UHVDC system with hierarchical connection mode. Changji–Guquan ±1100 kV UHVDC transmission project adopting hierarchical connection mode at receiving end. In this study, the effects of different DC block strategies when grounding faults occurred in both converter stations are compared based on PSCAD simulation. The simulation results indicate that the overvoltage at rectifier side has two stages while the overvoltage at inverter side has only one. Taking S block strategy can cause lower overvoltage but longer oscillation duration on grounding current. The proper block strategy for ±1100 kV UHVDC grounding faults is adopting S block at rectifier side and X block at inverter side.

DC grounding fault is a typical fault for HVDC system. In order to obtain smoother, faster, and more secure transient process, the DC protection block strategy is used to remove and isolate the converter to prevent the accident enlargement and reduce the impact on devices and power grid when the grounding fault is detected. Two main strategies are commonly taken in this situation: the X block for not >±500 kV and the S block for ±800 kV. There is no specific principle on the strategy choosing for ±1100 kV UHVDC system with hierarchical connection mode. Changji–Guquan ±1100 kV UHVDC transmission project adopting hierarchical connection mode at receiving end. In this study, the effects of different DC block strategies when grounding faults occurred in both converter stations are compared based on PSCAD simulation. The simulation results indicate that the overvoltage at rectifier side has two stages while the overvoltage at inverter side has only one. Taking S block strategy can cause lower overvoltage but longer oscillation duration on grounding current. The proper block strategy for ±1100 kV UHVDC grounding faults is adopting S block at rectifier side and X block at inverter side. [ABSTRACT FROM AUTHOR]

This study analyses a surge capacitor failure on the neutral bus in a ±500 kV high voltage direct current (HVDC) converter station. Both overvoltage and insulation of the surge capacitor are investigated through simulation, practical record data analysis, and experimentation. A highly accurate HVDC model is established on the basis of the topological structure and parameters of the HVDC project. Using this model, the failure process is simulated by combining neutral bus overvoltage record analysis and voltage divider performance test. Results indicate that the 246 kV uncharacteristically high overvoltage on the neutral bus is a measurement error caused by voltage divider fault. From the field test, difference equation of the voltage divider is derived to reconstruct the actual overvoltage, the amplitude of which is 73 kV. The amplitude is significantly lower than that of the switching impulse withstand level of the surge capacitor, which should not cause capacitor failure. Therefore, the primary cause of capacitor failure is insulation damage rather than overvoltage. Finally, maintenance measures are proposed and applied in the station. [ABSTRACT FROM AUTHOR]

The capacitor stack is one of main acoustic noise sources in the high-voltage dc (HVdc) converter station. It is necessary and important to estimate the noise level of capacitor stacks before an HVdc converter station is constructed. In this paper, based on the analysis of capacitor noise generation mechanisms, the relationship between the vibration speed and sound pressure level of the capacitor is identified. The equation which can be used to calculate the noise level of capacitor stacks is derived. By applying mechanical force on the capacitor tank, the frequency-response function of the capacitor tank vibration is acquired. And then the noise level of capacitor stacks is calculated and compared with the measurement data. The results show that the noise level of the capacitor stack can be predicted effectively with the proposed calculation method. [ABSTRACT FROM AUTHOR]

Audible noise of the filter capacitors in the HVDC converter station is severe and as loud as the converter transformer and, therefore, needs to be reduced. A microperforated-panel (MPP) absorber can be used because of its fibre-free nature and attractive appearance. In this paper, based on the mechanism of sound generation of capacitors and the electroacoustical equivalent circuit model of the MPP absorber, the MPP absorber for noise reduction of the filter capacitor in the HVDC converter station is first proposed, and then it is designed and installed at the bottom of the capacitor. An audible noise experiment of the capacitor with the MPP absorber is performed and compared with a regular capacitor's. The results validate that the MPP absorber is effective to reduce audible noise of the filter capacitors. [ABSTRACT FROM AUTHOR]