A kind of rural power grids low-voltage controlling device
Technical field
Low-voltage distribution field of the present invention, the device administered more particularly to the low-voltage distribution occasion low-voltage of rural power grids.
Background technology
At present there is the characteristics of user distribution is wide, and load, circuit is grown, and line loss is big in the rural power grids in China, and negative
The peak interval of time difference of lotus, seasonal variation are clearly.Such as between daytime, rural power load is generally relatively low, near zero load;
Night 18:00-21:During 00, load is generally heavier, near at full capacity.During slack season, rural power load is relatively low;Busy farming season and the Spring Festival
Period, load are again abnormal higher.This peak valley difference causes the user away from distribution transformer inclined in peak of power consumption period voltage
It is low.To solve the output voltage that this problem raises transformer, near-end user voltage can be caused higher again, and when load is relatively low
Section, the voltage of all users is all higher, influences the security and service life of user side electrical equipment.
The means of traditional improvement rural power grids low-voltage problem are to use load ratio bridging switch, are switched to according to the weight of load
On different transformer tappings, change output voltage, but rural power grids user disperses, simple regulation transformer output voltage, to remote
Nearly different user produces different regulating effects, it is difficult to dues attention to both short and long-range targets.Or using reactive power compensator, in low voltage
Increase the composition of capacitive reactive power, make transformer voltage lifting, effect is similar with load ratio bridging switch, it is also difficult to take into account far and near difference
User;Moreover the low voltage of rural power grids medium and long distance user is substantially the pressure drop that load current triggers on long cables, its
The component of middle watt current is heavier, is also difficult to receive satisfied effect so simple benefit is idle.And on a large scale to agriculture
The circuit of net is transformed, and increases number transformer and capacity, increases the cross-section of cable, although preferable effect can be obtained,
Invest huge, and the power consumption of rural power grids in itself is very limited, and income of electricity charge is not high, economically uneconomical.
Therefore, it is badly in need of the device that a kind of distribution occasion low-voltage is administered at present, power load distributing is uneven in solution rural power grids, and three
Mutually unbalanced problem.
The content of the invention
It is an object of the invention to provide a kind of rural power grids low-voltage controlling device, according to idle, harmonic wave in user side electric current, no
The degree of balance, is dynamically compensated so that transformer output voltage is more stable.
For achieving the above object, technical scheme provided by the invention is:
A kind of rural power grids low-voltage controlling device, including dynamic reactive compensation device and dynamic voltage adjustment device, the dynamic nothing
The AC of Reactive power compensation installations is connected on the output bus of distribution transformer, DC side connection storage capacitor, the energy storage electricity
Hold the DC side energy storage link also as dynamic voltage adjustment device, the inverter bridge of the dynamic voltage adjustment device is converted to DC voltage
Adjustable alternating voltage, and voltage scale is superimposed upon on the output bus of distribution transformer by series transformer;
The branch cable of near-end user is connected to the output end that distribution becomes electrical equipment, and the branch cable of remote subscriber is connected to string
Join the output end of transformer.
Further, the three-phase that the dynamic reactive compensation device is made up of 6 insulated gate bipolar transistor IGBTs
IGBT bridges, AC are connected on the output bus of distribution transformer by 3 reactors, and DC side is DC capacitor, described
The three-phase bridge that dynamic voltage adjustment device is made up of 6 insulated gate bipolar transistor IGBTs forms, and output passes through 3 filter reactors
It is connected on series transformer, according to the load current of remote subscriber, dynamically adjusts the dynamic voltage adjustment device triode
SPWM waveforms, the voltage for being output to series transformer are used to compensate the pressure drop lost on the cable of remote subscriber.
Further, according to three-phase imbalance composition in the total load electric current detected, idle composition, harmonic components it is big
It is small, control the SPWM waveforms of the dynamic reactive compensation device three-phase bridge so that mother is exported to distribution transformer by reactor
The current waveform injected on line can compensate for three-phase imbalance, idle composition, harmonic components.
Further, the dynamic reactive compensation device is made up of the capacitor of thyristor throw-cut, and 6 diodes are formed not
To control rectifier bridge and produce DC voltage, connect DC capacitor, the dynamic voltage adjustment device is made up of 6 IGBT three-phase bridges formed,
Output is connected on series transformer by 3 filter reactors, according to the load current of remote subscriber, dynamically adjust described in
The SPWM waveforms of dynamic voltage adjustment device triode, the voltage for being output to series transformer are used to compensate to damage on the cable of remote subscriber
The pressure drop of mistake.
Further, the dynamic reactive compensation device is made up of the three-phase bridge of three-level structure, and each bridge arm is by 4
IGBT and 2 diode is formed, and AC is connected on the output bus of distribution transformer by reactor, and DC side is direct current
Electric capacity, the dynamic voltage adjustment device are made up of 6 IGBT three-phase bridges formed, and output is connected to string by 3 filter reactors
Join on transformer, according to the load current of remote subscriber, dynamically adjust the SPWM waveforms of the dynamic voltage adjustment device triode,
The voltage for being output to series transformer is used to compensate the pressure drop lost on the cable of remote subscriber.
Further, it is made up of parallel three single phase devices, dynamic reactive compensation device is by 4 described in each single phase device
Individual triode forms the IGBT bridges composition of H bridges, and AC is connected on the output bus of distribution transformer by reactor to be injected
Electric current is compensated, DC side is DC capacitor, and the dynamic voltage adjustment device forms H bridges by 4 triodes and led to as IGBT bridges, output
Filter reactor is crossed to be connected on series transformer.
Using above-mentioned technical proposal, the present invention has the advantages that:
First, device of the invention is near-end, remote subscriber provides different supply voltages, while according to distal end load
The change dynamic regulation supply voltage of electric current, when load is heavier, the output voltage of series transformer is raised, on compensated line
Pressure drop;Output voltage that is on the contrary then reducing series transformer, makes remote subscriber voltage stablize the scope limited in standard as far as possible
Within.
Second, device of the invention can dynamically enter according to idle, harmonic wave, unbalanced degree in user side electric current
Row compensation so that transformer output voltage is more stable, and neutral line current maintains reduced levels as far as possible, and be unlikely to produce compared with
Big pressure drop, further the problem of improvement low-voltage.
3rd, the present invention in the design of pressure regulation part Capacity design it is very small, even if rectifier bridge operation in can produce
Certain harmonic wave, the deterioration of total harmonic wave and unobvious, while the complexity and cost of system can be reduced.
Brief description of the drawings
Fig. 1 is the structural representation in first preferred embodiment;
Fig. 2 is the structural representation in the second preferred embodiment;
Fig. 3 is the structural representation in third preferred embodiment;
Fig. 4 is the structural representation in the 4th preferred embodiment.
The implication of each reference is as follows in figure:
T1 represents that distribution transformer, T2 represent that series transformer, L represent that filter reactance, Q represent that triode, D represent two poles
Pipe, C represent electric capacity.
Embodiment
In order to make the purpose , technical scheme and advantage of the present invention be clearer, below in conjunction with the accompanying drawings and embodiment, it is right
The present invention is further elaborated.It should be appreciated that structure chart described herein and specific embodiment are only explaining this
Invention, is not intended to limit the present invention.
The present invention relates to a kind of rural power grids low-voltage controlling device, including dynamic reactive compensation device and dynamic voltage adjustment device,
The AC of dynamic reactive compensation device is connected on the output bus of distribution transformer, DC side connection storage capacitor, energy storage
DC side energy storage link of the electric capacity also as dynamic voltage adjustment device, the inverter bridge of dynamic voltage adjustment device is converted to DC voltage can
The alternating voltage of tune, and voltage scale is superimposed upon on the output bus of distribution transformer by series transformer;
The branch cable of near-end user is connected to the output end that distribution becomes electrical equipment, and the branch cable of remote subscriber is connected to string
Join the output end of transformer.
Embodiment 1
Fig. 1 is first preferred structure of the present invention, as shown in figure 1, T1 is the distribution transformer of rural power grids, the present apparatus is moved
State reactive-load compensation part forms three-phase IGBT bridges by triode Q1-Q6, and the AC of IGBT bridges passes through reactor L1-L3 connections
Onto distribution transformer T1 output bus, the DC side of IGBT bridges is DC capacitor C1, C2, and Q7-Q12 forms pressure regulation part
Three-phase IGBT bridges, output be connected to by filter reactance L4-L6 on series transformer T2.According to the load of remote subscriber electricity
Stream, Q7-Q12 SPWM waveforms are dynamically adjusted, the voltage for being output to series transformer is can compensate for the cable of remote subscriber
The pressure drop of upper loss, ensure remote subscriber side voltage in the range of positive and negative the 10% of nominal voltage.It is simultaneously total according to detecting
Three-phase imbalance composition, idle composition, the size of harmonic components in load current, control Q1-Q6 SPWM waveforms so that logical
Cross L1-L3 and can compensate for three-phase imbalance, idle composition, harmonic components to the current waveform that injects on T1 output buses, make
The output voltage for obtaining transformer T1 is as stable as possible.
For example, the impedance of the cable of remote subscriber is 0.3 Europe, when remote subscriber load current is 100A, amounted on cable
There is 30V pressure drop, therefore Q7-Q12 needs to export the SPWM waveforms of certain amplitude so that the output end voltage ratio of series transformer
The high 30V of input, the droop loss on compensating cable so that the voltage stabilization of user side is in 220V or so.In rural power grids
Power load distributing is uneven, and three-phase imbalance is relatively conventional, passes through Q1-Q6 regulation so that distribution transformer T1 output end, three
Phase current looks like balance, can reduce the loss of transformer, the output voltage of stabilizing transformer to greatest extent.
Embodiment 2
Fig. 2 is second preferred structure of the present invention, as shown in Fig. 2 dynamic reactive compensation device is by thyristor throw-cut
Capacitor is formed, and can be carried out idle and unbalanced classification switching and be administered;The uncontrollable rectifier bridge formed by diode D1-D6
Carry out rectification and produce direct current, the IGBT bridges for the pressure regulation part that Q7-Q12 is formed, rectifier bridge identical with the scheme shown in embodiment 1
Certain harmonic wave can be produced in operation, but it is very small because of the capacity of pressure regulation part, therefore deterioration and the unobvious of total harmonic wave, but
The complexity and cost of system can be reduced.Wherein, L1, L2, L3 represent filter reactance.
Embodiment 3
Fig. 3 is the 3rd preferred structure of the present invention, as shown in figure 3, dynamic reactive compensation device can use three level
The three-phase bridge of structure, i.e., each bridge arm can be made up of Q1-Q4 and D1, D2, taken such measure, can be reduced semiconductor
The voltage class of device, switching frequency is improved, so as to reduce L1-L3 capacity and reactor cost, dynamic voltage adjustment device and reality
Example 1 is applied as in 2, the IGBT bridges for the pressure regulation part that Q7-Q12 is formed, because its output capacity is smaller, three can be maintained
The scheme of half-bridge.
Embodiment 4
Fig. 4 is the 4th preferred structure of the present invention, as shown in figure 4, can be combined using three single-phase devices, with
Exemplified by a wherein phase, IGBT bridge of the H bridges as dynamic passive compensation part that Q1-Q4 is formed, the transformer by L1 to T1 is defeated
Go out injecting compensating electric current on bus, the voltage of DC side can be controlled in 400V or so, and the H bridges that Q7-Q10 is formed are as pressure-regulating portion
The IGBT bridges divided, regulation voltage is exported to T2 by L4.The advantages of structure of the present embodiment is that all semiconductor devices all may be used
Can be improved using the device of 600V grades, cheap and switching frequency;Three-phase is all identical structure, therefore can be entered
Row modularized design, it is easy to safeguard.
Embodiment described above only expresses embodiments of the present invention, and its description is more specific and detailed, but can not
Therefore it is interpreted as the limitation to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art,
Without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to the protection model of the present invention
Enclose.Therefore, the protection domain of patent of the present invention should be determined by the appended claims.