Longitudinal differential protection scheme for inverter interfaced distributed generator teed line

An inverter-type distributed, longitudinal differential protection technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve the problem of reducing the reliability of longitudinal differential protection, reduce the cost of transformation and improve reliability. Effect

Inactive Publication Date: 2015-07-15
TIANJIN UNIV
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Problems solved by technology

[0003] The purpose of the present invention is to overcome the problem of reduced reliability of the longitudinal differential protection after the inverter-type distribut

Method used

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  • Longitudinal differential protection scheme for inverter interfaced distributed generator teed line
  • Longitudinal differential protection scheme for inverter interfaced distributed generator teed line
  • Longitudinal differential protection scheme for inverter interfaced distributed generator teed line

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Embodiment Construction

[0020] The technical solution of the invention will be described in detail below in conjunction with the embodiments and with reference to the accompanying drawings.

[0021] This embodiment takes figure 1 The structure diagram shown is an example. The line AB in the figure is a line connected to an inverter distributed power supply. The system voltage level is 110kV. The phase angle difference of the power supply potentials on both sides of the system is 50°. The positive sequence impedance of the line is: Z= 0.21+0.419Ω / km, line susceptance: b 0 =2×10-6S / km. The lengths of lines AM, AT, BT, and BN are 30km, 30km, 15km, and 45km, respectively. The rated capacity of the inverter type distributed power supply is 30MW. The fault location is selected within the protection range of k 1 points and k outside the protection range 2 point, k 1 The distance between the point and the grid-connected point T of the inverter distributed power generation is 10km, k 2 The distance bet...

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Abstract

The invention relates to the field of relay protection containing distributed generation power systems and discloses a longitudinal differential protection scheme for an inverter interfaced distributed generator teed line. The scheme comprises steps as follows: (1) the setting values of a longitudinal protection device are initialized; (2) phase current information of lines A and B is acquired, and a three-phase voltage transformer acquires phase voltage information of buses A and B at two ends of each line and acquires positive-sequence components of voltages of the buses as well as positive-sequence components and negative-sequence components of currents of the lines; (3) home terminal information is transmitted to an opposite terminal by a communication channel, and the difference between phase currents, the difference between negative-sequence currents and the difference between positive-sequence offset voltages at two ends of each line are calculated; (4) measuring values and the setting values are compared, if one of the measuring values is larger than the corresponding setting value, a short-circuit fault is judged to occur in the protection range, and a protection outlet trips. The scheme effectively solves the problem of reduction of reliability of longitudinal differential protection for the inverter interfaced distributed generator teed line and has higher practicability in engineering practice.

Description

technical field [0001] The invention relates to the field of relay protection of power systems, and relates to an improved method for longitudinal differential protection after an inverter-type distributed power source is T-connected to a line. Background technique [0002] After the inverter-type distributed power supply is connected to the high-voltage distribution network with multi-terminal power supply to form a T-connection line, the three-stage current protection will not be able to meet the requirements of selectivity and reliability. The longitudinal differential protection occupies a pivotal position in the multi-terminal power supply network due to its good selectivity and quick action. However, when a large-capacity inverter distributed power supply is connected to the power system to form a T-connection line, the phase angle and amplitude of the current flowing into the longitudinal differential protection at both ends of the line have changed. When the system ...

Claims

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Application Information

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IPC IPC(8): H02H7/26
Inventor 李永丽刘幸蔚
Owner TIANJIN UNIV
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