Establishment and Application of Security Region Model of DC Distribution System

doi:10.12204/j.issn.1000-7229.2021.07.006

Abstract

Abstract:

The security of the DC distribution system requires the system to maintain the ability to supply power in response to a set of expected faults. N-1 check, which reflects the strength of system security, is used as a criterion for judging whether the system can continue to carry load under the condition of system fault. At present, no corresponding evaluation standard are studied on the security of DC distribution system. In order to study the transfer mechanism of fault sysem, open-loop topology is analyzed to establish a simplified security region model. Firstly, the parameters required by N-1 check are defined, and mathematical relationship between these parameters is derived, which is to reveal the network architecture of the system with fewer parameters. Secondly, the transfer mechanism of feederN-1 fault and converter station N-1 fault is analyzed. According to the defined parameters, the transfer process is described, and the N-1 constraint conditions of the feeders and converter stations are obtained. Therefore, the security region model is established. Thirdly, applying the security region model, the total supply capability of the system is calculated. Also, the relationship between power supply capability and load balance, which can be drawn as C_S-s² curve, is deduced. Thereafter, the optimal solution is found by using the entropy order method to analyze the curve. Finally, the feasibility of the model proposed in this paper is verified by comparing with existing security region model in the example.

Key words: DC distribution network, N-1 check, security, power supply capability

CLC Number:

TM744

MENG Xiangkun, HAN Minxiao, ZHANG Xiahui, CAO Wenyuan, MIAO Huiyu. Establishment and Application of Security Region Model of DC Distribution System[J]. ELECTRIC POWER CONSTRUCTION, 2021, 42(7): 48-57.

Figures/Tables 13

Fig.1 Asymmetric two-section connection mode

Table 1 Matrix values in asymmetric two-section connection mode

Fig.2 Transfer mechanism of feeder N-1 fault

Fig.3 Fault on the lower-level feeder

Fig.4 Transfer mechanism of N-1 fault between converter stations

Table A1 Typical connection mode

Table A2 Calculation results of security region model in typical connection mode

Fig.5 Flow chart for CS-s2 curve and optimal solution

Fig.6 Network configuration of the distribution system

Table A3 Calculation results of the example

Fig.7 Part of the network configuration

Table 2 Part of A1、A2 parameters corresponds to feeder 1

Fig.8 CS-s2 curve

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