An Evaluation Method of Single-Circuit HVDC Ultimate Feed-out Capacity of Sending-End Grid

doi:10.12204/j.issn.1000-7229.2021.11.009

Abstract

Abstract:

Large capacity UHVDC technology provides an effective means for long-distance and cross-regional power consumption of the sending-end power grid. However, with the increase of the number and capacity of HVDC, the contradiction of strong DC and weak AC is prominent. The fault of HVDC blocking will lead to an increasing threat to the frequency stability of the sending-end power grid, so the capacity of the HVDC is limited. In order to effectively quantify the extreme feed-out capacity of a single-circuit HVDC for providing references to evaluate the adaptability of the target grid, this paper proposes a method for single-circuit HVDC extreme feed-out capacity evaluation considering the frequency constraints. The proposed method firstly analyzes the frequency stability of the sending-end power grid under the scenario of large capacity HVDC bipolar lockout, and establishes the analytical expression between the transient frequency index and the capacity of HVDC lockout. Then, the second defensive line of power grid emergency control measures, such as the stability-control generator tripping and HVDC emergency active power support, are considered into the evaluation method, which can evaluate the extreme feed-out capacity of single-circuit HVDC that can be supported by the sending-end power grid under frequency stability constraints. Finally, an example simulation analysis is carried out on Sichuan Power Grid in 2030 to verify the effectiveness of the proposed method.

Key words: HVDC feed-out capacity, frequency stability, sending-end grid, HVDC emergency support, special unit tripping

CLC Number:

TM71

WANG Yunling, LI Ting, YANG Weifeng, XU Weiting, GOU Jing, LIU Fang, WEN Yunfeng. An Evaluation Method of Single-Circuit HVDC Ultimate Feed-out Capacity of Sending-End Grid[J]. ELECTRIC POWER CONSTRUCTION, 2021, 42(11): 82-89.

Figures/Tables 10

Fig.1 Primary frequency progress of power system

Table 1 HVDC operating status in Sichuan power grid in 2030 in the mode with high proportion hydropower and large load

Fig.2 Geography map of Sichuan power grid in 2030

Fig.3 Frequency curve following the 8 000 MW Sichuan-Zhejiang HVDC bipolar block

Fig.4 Relationship between the frequency deviation and Bai-Zhe HVDC capacity

Fig.5 Frequency curves following Bai-Zhe HVDC bipolar block with different power capacities

Table 2 Frequency extreme following Bai-Zhe HVDC bipole block with different power capacities

Fig.6 Frequency curve with Bai-Zhe HVDC bipolar block with HVDC emergency support and special unit tripping

Table 3 Bai-Zhe HVDC bipolar block capacity and its transient frequency extremum with the HVDC emergency support and special unit tripping

Fig.7 The output power in the scene of the HVDC emergency support

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