DC Yard Research Articles

Research on Magnetic Field Characteristics in DC Yard of Dinghai Converter Station Under Monopolar Grounding Fault

In Dinghai converter station of Zhoushan VSC-HVDC transmission project, 200 kV hybrid DC circuit breaker is used for the first time to realize DC side fault isolation. When DC side short circuit occurs, its fault current characteristics are different from those of AC substation and HVDC converter station, and the magnetic field interference to secondary equipment in DC yard is still unknown. In this paper, taking the single pole grounding short circuit fault with high probability in flexible DC power grid as an example, the electromagnetic transient simulation model of fault current in Dinghai converter station is established, and the time-domain current waveform is obtained. Then, the magnetic field calculation model of DC circuit breaker and other key electrical equipment is established, and the magnetic field of secondary equipment in DC yard is calculated based on Biot-Savart Law. The results show that the maximum magnetic field strength at the secondary equipment is 59 A/m, the waveform is ms level, and it is aperiodic. The distribution of magnetic field in DC yard varies between 3 and 346 A/m.

Electric field evaluation and optimization of shielding electrodes for high voltage apparatus in ±1100 kV indoor DC yard

The indoor DC yard of the ±1100 kV UHVDC transmission project is preferred to the outdoor solution, and the rational design of shielding electrodes for the ±1100 kV apparatus becomes the key to system security. In this paper, the design requirements of indoor DC yards were described and the preliminary designs of the indoor shielding electrodes for the key ±1100 kV DC apparatus were proposed. The whole 3-D FEM model of one ±1100 kV indoor DC yard was established. An empirical formula of the critical E-field strength for the evaluation of relatively large shielding electrodes was proposed based on the corona tests of typical ball and ring electrodes. The electric field distribution of the whole indoor DC yard was calculated and the surface electric field strength of all the shielding electrodes for the key ±1100 kV apparatus was evaluated. The results show that after optimization, the maximum surface field strength on the shielding electrode of ±1100 kV DC filter capacitor decreased from 1507 V/mm to 1335 V/mm, lower than the critical value for evaluation, then the corona free design of all the ±1100 kV indoor shielding electrode could be predicted. The method of electric field evaluation and optimization could provide important references for the development of shielding electrodes in the ±1100 kV or other UHV indoor DC yards.

Erratum: RF power injected into the DC yard by an HVDC convertor pole

Erratum: RF power injected into the DC yard by an HVDC convertor pole

Radio frequency spectral characteristics of an HVDC converter station

The radio frequency (RF) energy levels in a DC converter switchyard and valve halls have been measured in order to gain insight into the RF performance of converter stations. Detailed extended spectral records were taken at selected points within the valve halls, and at selected points and traverses in the DC yard to establish the converter station characteristic or signature. The purpose of the study is the detection and absolute quantification of the electric and magnetic field strengths at the test locations. To obtain the maximum amount of information about a converter pole when it is considered as an RF source, swept frequency (broad band) noise measurements were selected as the prime records for the analysis of the performance. The principal source of the RF noise is clearly the igniting valve. Several observations were made based on the measurements related to the initial slope of the voltage collapse recorded within the valve hall, the role of the distant grounding electrode, and the ignition pulse that produces an ω −2 spectral decay. The information will prove useful for (a) identification of the phenomena or station components shaping the station signature, (b) potential RF filtering applications in transmission line carrier bands, (c) the comparison of field and model tests performed by similar but scaled instrumentation systems.

RF power injected into the DC yard by an HVDC convertor pole

A new estimate has been made of the RF power injected by an HVDC convertor pole into the DC yard. The RF power levels measured provide a design basis for either an active or passive RF filter for the protection of a power-line carrier system of a convertor station of this type.