A Coordinated Control Method for Improving the Stability of Cascaded Hybrid HVDC Transmission System

A hybrid DC and power transmission system technology, applied in the direction of AC network circuits, circuit devices, electrical components, etc., to achieve the effect of simple and easy control strategy, preventing large-scale power transfer phenomenon, and improving stability

Active Publication Date: 2022-06-28
JIANGSU ELECTRIC POWER RES INST +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This measure proposes a recovery control strategy for the hybrid cascaded DC transmission system during the DC fault period and after the fault is cleared, which alleviates the overcurrent phenomenon during the fault period, but the control strategy is only for DC faults

Method used

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  • A Coordinated Control Method for Improving the Stability of Cascaded Hybrid HVDC Transmission System
  • A Coordinated Control Method for Improving the Stability of Cascaded Hybrid HVDC Transmission System
  • A Coordinated Control Method for Improving the Stability of Cascaded Hybrid HVDC Transmission System

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0032] Example: build as figure 1 The cascaded hybrid DC transmission system is shown as an example for verification, and its main parameters are shown in Table 1.

[0033] Table 1: Main Parameters of Cascade Hybrid DC Transmission System

[0034]

[0035]

[0036] The rectifier side LCC is controlled by constant DC current, and the inverter side LCC is controlled by constant DC voltage. The MMC control mode is shown in Table 2. MMC1 is constant DC voltage control, MMC2 and MMC3 are constant active power control, and their reactive power control adopts constant reactive power control, and the command value is set to 0.

[0037] Table 2: MMC Control Mode

[0038]

[0039]Verification scheme 1: Set a single-phase ground fault on the AC bus of the rectifier side, the fault starts from 4s and lasts for 0.5s

[0040] When the coordinated control strategy is not adopted, the following Figure 4 As shown in (a), at the moment of 4s, the rectifier side fails, the AC bus v...

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Abstract

The invention discloses a coordinated control method for improving the stability of a cascaded hybrid direct current transmission system. When a fault occurs, according to the transmission power of the line, the output power of the LCC on the inverter side, and the steady-state output power of the constant direct current voltage MMC, the multi-drop point MMC is controlled. The active power command value is regulated to avoid the conversion of the constant DC voltage station from inverter to rectifier, and to prevent the phenomenon of large-scale transfer of power on the AC side of the receiving end. At the same time, after the fault is cleared, the problem of large fluctuations in the system recovery process can still be alleviated, so that the system can quickly and smoothly return to the rated operating state. The invention can realize the smooth transition of the system under typical faults of AC and DC, and improve the stability of the DC receiving end system.

Description

technical field [0001] The invention relates to the technical field of direct current transmission, in particular to a coordinated control method for improving the stability of a cascaded hybrid direct current transmission system. Background technique [0002] For rectification using grid commutation converter LCC, inverter side using LCC and modular multi-level converter MMC in series with the receiving-end multi-drop cascade hybrid DC transmission system, due to the limitation of the manufacture of power devices It is usually necessary to use multiple MMCs in parallel to match the transmission capacity of the LCC and improve the transmission capacity of the entire system. The system topology is as follows: figure 1 shown. The existence of the LCC and MMC parallel group enables the receiving end to have the conditions for decentralized access to the AC power grid, and can form a multi-drop form that meets the electricity demand of multi-load centers. At the same time, bec...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/36H02J3/24
CPCH02J3/36H02J3/24H02J2203/10H02J2203/20Y02E60/60
Inventor 赵静波朱鑫要廖诗武徐珂曾蕊李保宏
Owner JIANGSU ELECTRIC POWER RES INST
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