A distribution network pilot protection system with inverter-type distributed power supply

An inverter-type distributed and longitudinal protection technology, applied in emergency protection circuit devices, emergency protection data processing devices, electrical components, etc., can solve the problems of single load type and small change in operation mode, and achieve improved selectivity. The effect of missing and reliability degradation, dynamic reflection of topology changes, and good engineering application value

Active Publication Date: 2022-07-29
SHANDONG UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, traditional directional elements are mainly used in small changes in operation mode, relatively single load type, or simple circular transmission and distribution networks to judge the fault direction, so that the existing traditional fault directional elements cannot meet its requirements

Method used

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  • A distribution network pilot protection system with inverter-type distributed power supply
  • A distribution network pilot protection system with inverter-type distributed power supply
  • A distribution network pilot protection system with inverter-type distributed power supply

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] like figure 1 As shown in the figure, the structure diagram of the PQ control mode of the IIDG inverter according to the present invention when a symmetrical fault occurs in the distribution network is shown, including:

[0040] In order to simplify the influence of time variables in the three-phase static coordinate system on the control system, the Park change is usually used to convert the AC quantity in the three-phase static abc coordinate system into the DC quantity in the synchronously rotating dq coordinate system.

[0041] The mathematical model of the available IIDG in the three-phase rotating coordinate system is as follows:

[0042]

[0043]The actual current measurement values ​​id and iq in the dq coordinate system continue to perform PI adjustment, feedforward and coupling compensation to obtain the voltage control signals ud* and uq* that satisfy the following equations. The transfer function and control block diagram of the current inner loop control...

Embodiment 2

[0062] According to the difference characteristics of the fault sequence component in the short-circuit current fed by the IIDG at the installation location of the fault directional component and the fault sequence component in the short-circuit current provided by the distribution network side to the fault point; whether the negative sequence voltage fault component at the installation location can be measured and when According to the characteristics of three-phase voltage drop amplitude and short-circuit current rise amplitude when a symmetrical fault occurs on grid-connected feeders, a new method for judging fault directional components suitable for faults occurring on IIDG grid-connected feeders is proposed. The working flow chart of the fault directional element on the IIDG grid-connected feeder is as follows: Figure 5 shown.

[0063] According to the difference characteristics of sequence current and voltage components in forward and reverse faults under different faul...

Embodiment 3

[0098] like Image 6 , ΔU'α and ΔUmα correspond to ΔU'1α, ΔU'2α, ΔU'3α, ΔU'4α and ΔUm1α, ΔUm2α, ΔUm3α, ΔUm4α, respectively, when faults occur at different positions, α=0, 1, 2 respectively represent zero sequence , positive and negative sequence components. Based on the power frequency sequence component variation direction element, the following corrections are made:

[0099] (1) When the forward fault occurs

[0100] |ΔU′ α |>|ΔU mα |

[0101] (2) When reverse fault occurs

[0102] |ΔU′ α |mα |

[0103]After the correction of the criterion, the directional element only needs to judge the magnitude relationship between ΔU'α and ΔUmα, and then the fault direction can be judged. The protection range of the directional element is expanded, and when a short circuit occurs outside the positive direction area, the directional element can still operate correctly. The fixes for the malfunctioning steering wheel bureau are as follows:

[0104] (1) When the forward fault occu...

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Abstract

The invention discloses a longitudinal protection system for a distribution network including an inverter-type distributed power source, studies the grid-connected topology and working principle of IIDG, and analyzes the negative sequence current suppression control of the inverter in PQ and double dq The output characteristics of IIDG under the strategy; the suppression principle of the grid-connected isolation transformer for the zero-sequence fault component is introduced, and the working principle of the fault directional components installed at different positions is studied; The distributed area pilot protection method of the Agent unit can quickly complete the fault location and fault area isolation in the distribution network. The invention not only designs a fault directional element suitable for the IIDG distribution network, but also proposes a distributed area longitudinal protection strategy applied to the distribution network. It is of great significance to study relay protection strategies and directional elements suitable for smart distribution networks.

Description

technical field [0001] The invention relates to the technical field of distribution network longitudinal protection, in particular to a distribution network longitudinal protection system including an inverter-type distributed power source. Background technique [0002] The statements in this section merely provide background related to the present disclosure and do not necessarily constitute prior art. [0003] With the emergence of smart grid, the construction scale of distribution network has been expanding. After a large number of distributed power sources are connected to the distribution system, it solves many inherent problems of traditional power grids, but also brings many adverse effects to the fault diagnosis of the distribution network. The existing traditional directional elements and relay protection strategies are difficult to meet its requirements. Therefore, how to correctly determine the fault direction in a smart distribution network with a large number ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/28H02H1/00
CPCH02H7/28H02H1/0092
Inventor 张超陈子健刘梦瑶刘兆栋宋娜吴旋旋张国超孙泉杜晓光王怀宇李润
Owner SHANDONG UNIV OF SCI & TECH
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