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Flexible DC transmission device, control method thereof and control device

A flexible DC transmission and power grid technology, applied in the electric power field, can solve problems such as limited voltage sag capability, increased investment cost, and unresolved issues, and achieve the effects of controlling voltage sag, reducing investment cost, and reducing required capacity

Inactive Publication Date: 2017-11-07
SHANGHAI MERCHANT SHIP DESIGN & RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the sudden increase of load in the power grid is caused by the start-up of a large motor, which is an instantaneous process with the characteristics of short time and large impact. The special use of a large-capacity flexible DC transmission device for this situation will generate certain waste and increase investment costs.
[0004] Aiming at the above-mentioned problem of limited ability of flexible DC transmission devices to deal with voltage sags in the prior art, no effective solution has been proposed so far

Method used

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  • Flexible DC transmission device, control method thereof and control device
  • Flexible DC transmission device, control method thereof and control device
  • Flexible DC transmission device, control method thereof and control device

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Embodiment 1

[0047] Embodiment 1 of the present invention provides a control method for a flexible direct current transmission device, figure 2 It is a schematic flow chart of a control method for a flexible direct current transmission device of the present invention, including the following steps:

[0048] Step S21, when the load terminal voltage of the grid is lower than the standard value, the current total output power of the flexible direct current transmission device is detected.

[0049] When a sudden increase in load occurs in the grid, it will cause a voltage sag, making the load terminal voltage of the grid lower than the standard value. The standard value can be 380V or 220V according to different grid types. When the voltage at the load terminal is lower than the standard value, it is necessary to check the current working status of the flexible direct current transmission device to determine whether the total output power of the device has reached the maximum output power, th...

Embodiment 2

[0075] Embodiment 2 of the present invention provides another control method for a flexible direct current transmission device, Figure 5 It is a schematic flow chart of a control method for a flexible direct current transmission device of the present invention, including the following steps:

[0076] Step S51, detecting the load terminal voltage of the grid in real time.

[0077] Step S52, judging whether the load terminal voltage is higher or lower than a standard value. If it is higher than the standard value, execute step S53; if it is lower than the standard value, execute step S56.

[0078] Step S53, when the load terminal voltage of the grid is higher than the standard value, reduce the output value of reactive power of the device until the load terminal voltage reaches the standard value or the output value of reactive power reaches the minimum value.

[0079] Step S54, if the output value of the reactive power reaches the minimum value, obtain the difference between...

Embodiment 3

[0087] An embodiment of the present invention provides a control device for a flexible direct current transmission device, see Image 6 The schematic structural diagram of the control device of the flexible DC transmission device shown includes a detection module 61, a reactive power adjustment module 62, a voltage deviation acquisition module 63 and a coordination control module 64. The functions of the above modules are as follows:

[0088] A detection module 61, configured to detect the current total output power of the flexible direct current transmission device when the load terminal voltage of the grid is lower than a standard value;

[0089] The reactive power adjustment module 62 is used to increase the output value of the reactive power of the device if the total output power does not reach the total capacity of the device until the load terminal voltage reaches the standard value or the output value of the reactive power reaches the saturated reactive capacity;

[00...

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PUM

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Abstract

The invention provides a flexible DC transmission device, a control method thereof and a control device, which relate to the technical field of power. The method comprises steps: when the load-end voltage of a power grid is lower than a standard value, the current general output power of the above device is detected; if the general output power does not reach the general capacity of the device, the output value of reactive power of the device is improved until the load-end voltage reaches the standard value or the output value of the reactive power reaches a saturated reactive power capacity; if the output value of the reactive power reaches the saturated reactive power capacity, the offset between the current load-end voltage and the standard value is acquired; and when the offset exceeds a threshold, the output value of the active power and the output value of the reactive power are adjusted respectively to enable the offset to be smaller than the threshold. Coordinated adjustment can be carried out on the active power and the reactive power, the capacity of the flexible DC transmission device is used with greater efficiency to enhance the voltage of the power grid, voltage sag can be treated effectively, the capacity needed by the flexible DC transmission device is reduced, and the investment cost is reduced.

Description

technical field [0001] The invention relates to the field of electric power technology, in particular to a flexible direct current transmission device, a control method and a control device thereof. Background technique [0002] Flexible DC transmission (Voltage Source Converter based High Voltage Direct Current Transmission, VSC-HVDC) devices are often used for grid interconnection, and the active power and reactive power are controlled separately. When the grid load suddenly increases and causes a voltage sag, the active power transmitted by the flexible DC transmission device remains unchanged, and the reactive power is controlled according to the voltage of the grid. However, limited by the capacity of the flexible DC transmission device itself, the reactive power it can output is limited, and the ability to adjust voltage is also limited, which may cause voltage sags in the grid and fail to meet the requirements of relevant grid regulations. [0003] In order to effect...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/36
CPCH02J3/36H02J2003/365Y02E60/60
Inventor 黄建涛陈默谢珉
Owner SHANGHAI MERCHANT SHIP DESIGN & RES INST