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Low voltage control device for rural power grid

A low-voltage, rural power grid technology, applied in the direction of circuit devices, harmonic reduction devices, AC network voltage adjustment, etc., can solve the problems of three-phase imbalance, increase the output voltage of transformers, and low voltage, so as to reduce complexity and The effect of lower cost, higher output voltage, and stable output voltage

Active Publication Date: 2016-06-22
BEIJING IN POWER ELECTRIC +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This peak-to-valley difference leads to low voltage for users far away from distribution transformers during peak hours of power consumption
In order to solve this problem, increasing the output voltage of the transformer will lead to high voltage of near-end users, and in the period of low load, the voltage of all users is high, affecting the safety and service life of user-side electrical appliances
[0003] The traditional way to solve the problem of low voltage in the rural power grid is to use the on-load tap changer to switch to different transformer taps according to the weight of the load to change the output voltage. Different users have different adjustment effects, and it is difficult to take into account both near and far
Or use a reactive power compensation device to increase the capacitive reactive power component when the voltage is low, so that the voltage of the transformer can be raised. The effect is similar to that of an on-load tap changer, and it is also difficult to take into account users of different distances; besides, the voltage of long-distance users in rural power grids The low voltage is essentially the voltage drop caused by the load current on the long cable, and the active current has a heavier component, so it is difficult to achieve satisfactory results simply by supplementing reactive power
However, large-scale transformation of the lines of the rural power grid, increasing the number and capacity of transformers, and increasing the cross-section of cables can achieve better results, but the investment is huge, and the power consumption of the rural power grid itself is very limited, and the income from electricity charges is not high. , economically uneconomical
[0004] Therefore, there is an urgent need for a low-voltage control device for power distribution occasions to solve the problems of uneven load distribution and three-phase imbalance in rural power grids.

Method used

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  • Low voltage control device for rural power grid

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Effect test

Embodiment 1

[0028] figure 1 It is the first preferred structure of the present invention, such as figure 1 As shown, T1 is the distribution transformer of the rural power grid. The dynamic reactive power compensation part of this device is composed of triodes Q1-Q6 to form a three-phase IGBT bridge. The AC side of the IGBT bridge is connected to the output of the distribution transformer T1 through reactors L1-L3 On the bus, the DC side of the IGBT bridge is the DC capacitors C1, C2, Q7-Q12 constitute the three-phase IGBT bridge of the voltage regulation part, and the output is connected to the series transformer T2 through the filter reactance L4-L6. According to the load current of the remote user, dynamically adjust the SPWM waveform of Q7-Q12, so that the voltage output to the series transformer can compensate the voltage drop lost on the cable of the remote user, and ensure that the voltage of the remote user side is in the positive range of the nominal voltage In the minus 10% rang...

Embodiment 2

[0031] figure 2 It is the second preferred structure of the present invention, such as figure 2 As shown, the dynamic reactive power compensation device is composed of thyristor switching capacitors, which can perform reactive power and unbalanced switching management; rely on the uncontrolled rectifier bridge composed of diodes D1-D6 to rectify and generate DC, Q7-Q12 The IGBT bridge of the voltage regulating part is the same as the scheme shown in Embodiment 1. Certain harmonics will be generated during the operation of the rectifying bridge, but because the capacity of the voltage regulating part is very small, the deterioration of the total harmonics is not obvious. But it can reduce the complexity and cost of the system.

Embodiment 3

[0033] image 3 is the third preferred structure of the present invention, such as image 3 As shown, the dynamic reactive power compensation device can adopt a three-phase bridge with a three-level structure, that is, each bridge arm can be composed of Q1-Q4 and D1, D2. Taking such measures can reduce the voltage level of semiconductor devices and improve the switching efficiency. Frequency, thereby reducing the capacity of L1-L3 and the cost of the reactor. The dynamic voltage regulation device is the same as in Embodiment 1 and 2. The IGBT bridge of the voltage regulation part composed of Q7-Q12 can maintain three voltage because of its small output capacity. Half-bridge scheme.

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Abstract

The invention provides a low voltage control device for a rural power grid. The low voltage control device comprises a dynamic reactive compensation device and a dynamic pressure regulating device, wherein an AC side of the dynamic reactive compensation device is connected to an output bus of a distribution transformer, a DC side is connected with an energy storage capacitor, the energy storage capacitor is also used as a DC side energy storage link of the dynamic pressure regulating device, an inverter bridge of the dynamic pressure regulating device converts a DC voltage into an adjustable AC voltage, and a parallel series transformer superposes the voltage on the output bus of the distribution transformer according to a proportion. The device provided by the invention provides different power supply voltages for close and remote users and meanwhile dynamically adjusts the power supply voltages according to the change of the remote load current, so that the voltages of the remote users can be stabilized within a standard limited range as much as possible.

Description

technical field [0001] The invention relates to the field of low-voltage power distribution, in particular to a low-voltage control device for low-voltage power distribution occasions in rural power grids. Background technique [0002] At present, my country's rural power grid has the characteristics of wide distribution of users, scattered load, long lines and large line loss, and the difference between peak and valley periods and seasonal differences of load is very obvious. For example, during the daytime, the load of the rural power grid is generally low, almost no load; during the period of 18:00-21:00 at night, the load is generally heavy, almost full load. During the slack season, the load on the rural power grid is relatively low; during the busy farming season and the Spring Festival, the load is extremely high. This peak-to-valley difference leads to low voltage for users far away from distribution transformers during peak hours of power consumption. In order to ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/18H02J3/26H02J3/01H02J3/12
CPCH02J3/01H02J3/12H02J3/1842H02J3/26Y02E40/30Y02E40/40Y02E40/50
Inventor 郭春雨马丰民瞿文慧孙大伟邢勇张洪涛李静
Owner BEIJING IN POWER ELECTRIC