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Automatic load-reducing control method for integrating the voltage frequency dynamic mutual influence

A technology of dynamic interaction and voltage frequency, applied in the direction of AC network voltage adjustment, electrical components, circuit devices, etc., can solve problems such as difficult dynamic interaction, redundant load shedding, and control device refusal to avoid large-scale power outages, Avoiding safe and stable damage and reducing the effect of load shedding

Active Publication Date: 2009-11-25
NARI TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In some cases, relying on traditional underfrequency load shedding control strategies using only frequency measurement, or LV load shedding control strategies using only voltage measurement, or even if both underfrequency and LV load shedding controls are configured, each control Both are still based on a single frequency measurement or a single voltage measurement and an automatic load shedding control strategy that acts independently. It is difficult to truly reflect the dynamic interaction between the disturbed system voltage and frequency, and it is also difficult to adapt to the load characteristics of the system during operation. or changes in fault types, which may lead to serious under-control or over-control, and even cause blackouts
In other words, the change of frequency or voltage alone sometimes cannot trigger the device to act normally, resulting in the refusal of the control device; or causing the device to operate excessively, and the load is cut off redundantly, resulting in unnecessary economic losses
[0006] Therefore, because the traditional automatic load shedding control method does not consider the dynamic interaction between voltage and frequency in the real-time control algorithm, there is a danger of the control device refusing to operate or over-cutting, resulting in serious consequences for power grid security or economy.

Method used

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  • Automatic load-reducing control method for integrating the voltage frequency dynamic mutual influence
  • Automatic load-reducing control method for integrating the voltage frequency dynamic mutual influence
  • Automatic load-reducing control method for integrating the voltage frequency dynamic mutual influence

Examples

Experimental program
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Effect test

example 1

[0045]Example 1: An embodiment of an automatic load shedding control method for different operating conditions

[0046] The geographic wiring of an actual receiving power grid (region A) is as follows: Figure 5 shown. The power grid in this area is connected to the main grid through two 500kV double-circuit lines of Bus1-Bus3 and Bus2-Bus3. When a main transformer of Bus3 fails, the transformer protection action cuts it off, and at the same time the other main transformer protection malfunctions, the isolated network in this area operates and there is a large power shortage. If part of the load cannot be removed quickly, it will cause a rapid collapse of frequency or voltage.

[0047] Considering three different operation modes, under each mode, the power received by the power grid from the external network accounted for 9%, 19%, and 27% of the total load in the area. It is assumed that each main load node in the grid has been equipped with an automatic load shedding contr...

example 2

[0057] Example 2: An embodiment of an automatic load shedding control method for different load characteristics

[0058] Variations in load characteristics can be characterized by different descriptions of the load model. Different load characteristics have a great influence on the transient voltage and transient frequency response after a fault, but the traditional low-frequency and low-voltage load shedding control method does not consider the influence of load characteristics on the dynamic process of the system in the real-time control algorithm, so it is difficult to compare Adapt to changes in load characteristics well, and in some cases may cause the device to refuse to move and cause the grid to collapse.

[0059] still with Figure 5 The mode 3 of the power grid in region A is shown as an example, and the fault scenario is the same as that of example 1. Two types of load models are considered: model 1 is static load, and model 2 is comprehensive load considering a c...

example 3

[0062] Example 3: An embodiment of an automatic load shedding control method for different fault types

[0063] by Image 6 The power grid in region B is shown as an example. The five small power plants in the whole network are responsible for 60.5% of the load power supply in the network, and a certain amount of hot backup is left (the hot backup capacity accounts for 10.9% of the total load of the whole network). In normal operation mode, about 40% of the load demand needs to be received from the main network through the 500kV double circuit line between Bus1-Bus2.

[0064] When the bus1-bus2 double circuit of the connection line is suddenly disconnected due to a fault, the area will operate in isolation, and there will be a large power shortage. It is necessary to quickly remove the excess load through the load shedding control device.

[0065] After the time-domain simulation of the power grid, it is found that when the tie line is disconnected in different fault forms, t...

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Abstract

An Automatic load-reducing control method for integrating the voltage frequency dynamic mutual influence measures the state quantity information on site such as voltage, frequency and power so as to determine whether to act for implementing the load-reducing. The invention effectively takes account of the coupling degree of the voltage amount and the frequency amount under the corresponding operating condition by calculating the average frequency voltage correlation coefficient at the device installation nodes under a certain operating condition; calculating the synthetic state quantity in real time by measuring the voltage, frequency and active power of the installation node of each automatic load-reducing control device in real time and starting the automatic load-reducing control device in time based on the change circumstance, and acting in turn. The invention introduces the active power measurement into the traditional automatic load-reducing device, takes account of the interaction of the voltage and the frequency generated by the load active power and solves the problem that the device may not act or act excessively only based on the change of the frequency amount or the voltage amount.

Description

technical field [0001] The invention belongs to the technical field of electric power system automation, and more precisely, the invention relates to an automatic load shedding control method that integrates dynamic interaction effects of voltage and frequency. Background technique [0002] The automatic load shedding control of the power system is an important technical means to prevent the power grid, especially the receiving end power grid, from causing stability damage and large-scale power outages after suffering extremely serious faults. [0003] In order to ensure that after a sudden power shortage occurs in the grid, the reserved operating load capacity can adapt to the operating generating capacity at any time, and the voltage and frequency of each node in the grid can be restored to the rated value quickly, and an automatic load shedding control device must be configured. [0004] The existing low-frequency and low-voltage automatic load shedding control only trigg...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/00H02J3/14
CPCY02B70/3225Y04S20/222
Inventor 方勇杰杨卫东侯玉强鲍颜红徐泰山李碧君刘福锁许剑冰薛禹胜张长银姬长安李雪明罗剑波
Owner NARI TECH CO LTD
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