CN107769367A - Load seamless switching device is pressed in a kind of distribution based on solid-state switch - Google Patents

Abstract

The invention provides load seamless switching device is pressed in a kind of distribution based on solid-state switch, load seamless switching device is pressed to include working power in the distribution, first sensor, first solid-state switch, stand-by power supply, second sensor, second solid-state switch, intelligent microprocessor control system, 3rd sensor and electrical equipment, under normal condition, second solid-state switch is off, when intelligent microprocessor control system detects working power failure, send control instruction and make it that the first solid-state switch disconnects and the second solid-state switch turns on to the first solid-state switch and the second solid-state switch, status information feedback is returned intelligent microprocessor control system by the first solid-state switch and the second solid-state switch simultaneously.By the present invention in that with all-controlling power electronics device, the switch speed of automatic change-over is effectively improved, realizes load seamless switching, and handoff procedure produces without electric arc, and life and reliability will also be increased dramatically.

Description

A seamless switching device for medium-voltage loads in distribution networks based on solid-state switches

technical field

The invention belongs to the technical field of power grid voltage regulation, and in particular relates to a medium-voltage load seamless switching device for a distribution network based on a solid-state switch.

Background technique

With the development of the power system, the power grid is becoming more and more complex, the types of power sources and loads are increasing, and the reliability of power supply is becoming more and more prominent. Power supply reliability refers to the ability of the power supply system to continuously provide users with qualified electric energy. It is an important indicator for assessing the power quality of the power supply system. It reflects the degree to which the power industry meets the power demand of the national economy. It has become a measure of a country's economic development. one of the standards. In 2009, the State Grid proposed the concept of building a strong and smart grid, pointing out that "a strong and smart grid is a grid that is safe, reliable, cost-effective, clean and environmentally friendly, transparent, open, and friendly." Power supply reliability, as an aspect of power supply quality, is listed as a characteristic and construction goal of a strong smart grid, and has received more and more attention. With the development of high-tech industries and large-scale industrial enterprises, industrial loads such as high-precision instruments, semiconductor industry, and large-scale industrial and mining enterprises have increasingly high requirements for power supply reliability. Especially important large-scale industrial enterprises related to the national economy and people's livelihood, such as iron and steel enterprises, put forward higher requirements for power supply reliability. For important industrial loads, short-term power outages or voltage drops of several cycles may lead to inferior products. In severe cases The production line is paralyzed, causing heavy losses to enterprises and society.

For hospitals, airports, large-scale production lines, banks, high-rise buildings, military facilities and other important power-consuming places, in order to ensure reliable power supply of large-capacity important loads, two independent power supply modes of main and backup are often used. Therefore, it is necessary to study the high-reliability, fast and seamless switching technology between power sources. Automatic transfer switch (Automatic Transfer Switching Equipment, ATSE) is an effective means to switch between power sources, and it is one of the important measures to improve the reliability of load power supply in large industrial enterprises. The automatic transfer switch is composed of one (or several) transfer switch appliances and other necessary appliances, which are used to detect the power circuit and automatically transfer one or more load circuits from one power supply to another. It has been widely used Applied in various sensitive industrial loads. For large-capacity industrial loads, the automatic transfer switch has low cost and reliable operation, and is an important means to solve the problem of power supply reliability.

At present, there are already many different types of automatic transfer switches on the market, and these automatic transfer switches meet the demand of the load to switch between the normal power supply and the backup power supply to a certain extent. However, with the development of the power system, the reliability of the power supply is required to be higher and higher, and the design of an automatic transfer switch with high reliability, fast and seamless switching is an urgent problem to be solved.

Contents of the invention

The medium-voltage load seamless switching device based on the power electronic solid-state switch of the present invention effectively improves the switching speed of the automatic transfer switch by using a fully-controlled power electronic device, realizes the seamless switching of the load, and has no arc generation during the switching process, and has a long service life and reliability Sexuality will also be greatly improved.

The present invention is specifically a medium-voltage load seamless switching device for a distribution network based on a solid-state switch. The medium-voltage load seamless switching device for a distribution network includes a working power supply, a first sensor, a first solid-state switch, a backup power supply, and a second sensor. , a second solid-state switch, an intelligent microprocessor control system, a third sensor and an electrical device, the working power supply is connected to the first solid-state switch through the first sensor, and the backup power supply is connected to the first solid-state switch through the second sensor connected to the second solid state switch, the first solid state switch and the second solid state switch are also connected to the third sensor, the third sensor is connected to the electrical device, the first sensor, The second sensor and the third sensor are also connected to the intelligent microprocessor control system, and the first solid state switch and the second solid state switch are also bidirectionally connected to the intelligent microprocessor control system, so The intelligent microprocessor control system sends a trigger pulse to the first solid-state switch and the second solid-state switch to control the on-off of the first solid-state switch and the second solid-state switch, the first solid-state switch and the second solid-state switch The second solid-state switch feeds status information to the intelligent microprocessor control system, which is also bidirectionally connected to a remote computer and a tie switch, and the intelligent microprocessor control system includes a microcontroller , switching value input circuit, switching value output circuit, analog-to-digital conversion circuit, keyboard, liquid crystal display, power supply, controller LAN bus interface and trigger signal optical fiber interface circuit; under normal conditions, the second solid state switch is in the off state, when the When the intelligent microprocessor control system detects the failure of the working power supply, it sends a control command to the first solid-state switch and the second solid-state switch so that the first solid-state switch is turned off and the second solid-state switch is turned on. on, while the first solid state switch and the second solid state switch feed back status information to the intelligent microprocessor control system.

Further, the first solid-state switch and the second solid-state switch include a main switch, an auxiliary switch, a thyristor switch, a detection circuit, a control unit and a surge arrester, and the detection circuit, the thyristor switch and the auxiliary switch are sequentially connection, the main switch is connected in parallel to both ends of the thyristor switch and the auxiliary switch, the arrester is connected in parallel to both ends of the thyristor switch and the auxiliary switch, and the detection circuit is connected to the control The control unit is also connected to the main switch, the auxiliary switch and the thyristor switch to control the on-off of the main switch, the auxiliary switch and the thyristor switch.

Further, the main switch and the auxiliary switch are IGBTs or IGCTs.

Further, the first solid-state switch and the second solid-state switch include a main switch, a detection circuit, a control unit, and a lightning arrester, the detection circuit is connected to the main switch, and the lightning arrester is connected in parallel to both sides of the main switch. terminal, the detection circuit is also connected to the control unit, and the control unit is also connected to the main switch to control the on-off of the main switch.

Further, the main switch is an IGBT or an IGCT.

Further, the turn-off process of the solid-state switch is specifically:

(1) When it is detected that the fault current rises to about 1.2 times the rated value, the auxiliary switch is turned off, and the current begins to transfer to the main circuit and continue to rise;

(2) With the current transfer, the current in the auxiliary branch gradually decreases, and when the current flowing through the thyristor switch drops below the holding current, the thyristor switch is turned off;

(3) After the thyristor switch is successfully turned off, it can withstand an overvoltage of 1.5 times. When it is detected that the current in the auxiliary branch is zero, the main circuit switch is turned off, and the overshoot of the turn-off voltage is borne by the thyristor switch. The current Start to transfer to the arrester branch and gradually descend;

(4) The decay time of the fault current in the arrester is 2ms. When the current decreases to zero, the solid-state switch completes a successful shutdown.

Further, the instantaneous detection of power supply voltage failure adopts the improved algorithm of three-phase d-q coordinate transformation:

When a voltage asymmetry fault occurs, the voltage amplitude obtained through the d-q coordinate transformation is a change, but the three-phase d-q coordinate transformation algorithm cannot make a quantitative analysis of this change. For this reason, the concept of voltage signal positive and negative sequence decomposition and d-q After the algorithm is combined, some changes are produced. The three-phase voltage of the system under the abc coordinates is transformed into the d-q coordinate system, the positive sequence component of the fundamental wave is changed into a DC component, the negative sequence component is changed into a second harmonic component, and the zero sequence component is still zero:

After performing d-q transformation on the three-phase voltage of the system under the above-mentioned abc coordinates, it is obtained:

Among them, U _a , U _b , U _c are the three-phase voltages of the system under abc coordinates, U ₁ is the fundamental wave component, U ₂ is the second harmonic component, U ₀ is the zero-sequence voltage, U _d , U _q are respectively d-axis, q-axis voltage;

When a grounding or short-circuit fault occurs, U _d and U _q not only contain positive sequence DC components, but also contain negative sequence double-frequency AC components. In order to separate the DC components in the dq coordinate system, the dq-transformed signal is passed through Low-pass filter, the output result is used as a criterion for judging whether a voltage drop occurs, namely:

Description of drawings

Fig. 1 is a structural schematic diagram of a medium-voltage load seamless switching device based on a solid-state switch of the present invention;

Fig. 2 is a schematic diagram of the composition of a solid-state switch according to the first embodiment of the present invention;

FIG. 3 is a schematic diagram of the composition of the solid-state switch according to the second embodiment of the present invention.

Detailed ways

The specific implementation of a solid-state switch-based medium-voltage load seamless switchover device for distribution networks of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the distribution network medium voltage load seamless switching device includes a working power supply, a first sensor, a first solid-state switch, a backup power supply, a second sensor, a second solid-state switch, an intelligent microprocessor control system, and a second solid-state switch. Three sensors and electrical equipment, the working power supply is connected to the first solid-state switch through the first sensor, the backup power supply is connected to the second solid-state switch through the second sensor, and the first solid-state switch is connected to the first solid-state switch. switch and said second solid state switch are also connected to said third sensor, said third sensor is connected to said powered device, said first sensor, said second sensor and said third sensor are also connected to The intelligent microprocessor control system, the first solid-state switch and the second solid-state switch are also bidirectionally connected to the intelligent microprocessor control system, and the intelligent microprocessor control system sends a trigger pulse to the first A solid-state switch and the second solid-state switch are used to control the on-off of the first solid-state switch and the second solid-state switch, and the first solid-state switch and the second solid-state switch feed back state information to the smart Microprocessor control system, said intelligent microprocessor control system is also bidirectionally connected with remote computer and contact switch, said intelligent microprocessor control system includes microcontroller, switch value input circuit, switch value output circuit, analog-to-digital conversion circuit, keyboard, liquid crystal display, power supply, controller local area network bus interface and trigger signal optical fiber interface circuit; under normal conditions, the second solid-state switch is in an off state, when the intelligent microprocessor control system detects that the working power supply fails , send a control instruction to the first solid-state switch and the second solid-state switch so that the first solid-state switch is turned off and the second solid-state switch is turned on, and at the same time the first solid-state switch and the second solid-state switch A solid state switch feeds status information back to the intelligent microprocessor control system.

As shown in Figure 2, the first solid-state switch and the second solid-state switch in the first embodiment of the present invention include a main switch, an auxiliary switch, a thyristor switch, a detection circuit, a control unit and a lightning arrester, the detection circuit, The thyristor switch and the auxiliary switch are connected sequentially, the main switch is connected in parallel to both ends of the thyristor switch and the auxiliary switch, and the arrester is connected in parallel to both ends of the thyristor switch and the auxiliary switch. end, the detection circuit is connected to the control unit, and the control unit is also connected to the main switch, the auxiliary switch and the thyristor switch to control the main switch, the auxiliary switch and the thyristor switch on-off control. The main switch and the auxiliary switch are IGBTs or IGCTs.

As shown in Figure 3, in the second embodiment of the present invention, the first solid-state switch and the second solid-state switch include a main switch, a detection circuit, a control unit and a lightning arrester, and the detection circuit is connected to the main switch , the lightning arrester is connected in parallel to both ends of the main switch, the detection circuit is also connected to the control unit, and the control unit is also connected to the main switch to control the on-off of the main switch. The main switch is IGBT or IGCT.

The turn-off process of the solid-state switch is as follows:

(5) When it is detected that the fault current rises to about 1.2 times of the rated value, the auxiliary switch is turned off, and the current begins to transfer to the main circuit and continue to rise;

(6) With the current transfer, the current in the auxiliary branch gradually decreases, and when the current flowing through the thyristor switch drops below the holding current, the thyristor switch is turned off;

(7) After the thyristor switch is successfully turned off, it can withstand an overvoltage of 1.5 times. When it is detected that the current in the auxiliary branch is zero, the main circuit switch is disconnected, and the overshoot of the turn-off voltage is borne by the thyristor switch. The current Start to transfer to the arrester branch and gradually descend;

(8) The decay time of the fault current in the arrester is 2ms. When the current decreases to zero, the solid-state switch completes a successful shutdown.

The instantaneous detection of power supply voltage failure adopts the improved algorithm of three-phase d-q coordinate transformation:

When a voltage asymmetry fault occurs, the voltage amplitude obtained through the d-q coordinate transformation is a change, but the three-phase d-q coordinate transformation algorithm cannot make a quantitative analysis of this change. For this reason, the concept of voltage signal positive and negative sequence decomposition and d-q After the algorithm is combined, some changes are produced. The three-phase voltage of the system under the abc coordinates is transformed into the d-q coordinate system, the positive sequence component of the fundamental wave is changed into a DC component, the negative sequence component is changed into a second harmonic component, and the zero sequence component is still zero:

After performing d-q transformation on the three-phase voltage of the system under the above-mentioned abc coordinates, it is obtained:

Among them, U _a , U _b , U _c are the three-phase voltages of the system under abc coordinates, U ₁ is the fundamental wave component, U ₂ is the second harmonic component, U ₀ is the zero-sequence voltage, U _d , U _q are respectively d-axis, q-axis voltage;

When a grounding or short-circuit fault occurs, U _d and U _q not only contain positive sequence DC components, but also contain negative sequence double-frequency AC components. In order to separate the DC components in the dq coordinate system, the dq-transformed signal is passed through Low-pass filter, the output result is used as a criterion for judging whether a voltage drop occurs, namely:

Finally, it should be noted that the combination of the above embodiments only illustrates the technical solution of the present invention rather than limiting it. Those of ordinary skill in the art should understand that those skilled in the art can modify or equivalently replace the specific embodiments of the present invention, but these modifications or changes are within the protection scope of the pending claims.

Claims (7)

1. load seamless switching device is pressed in a kind of distribution based on solid-state switch, it is characterised in that press load in the distribution Seamless switching device includes working power, first sensor, the first solid-state switch, stand-by power supply, second sensor, the second solid-state Switch, intelligent microprocessor control system, 3rd sensor and electrical equipment, the working power pass through the first sensor First solid-state switch is connected to, the stand-by power supply is connected to second solid-state switch by the second sensor, First solid-state switch and second solid-state switch are also connected to the 3rd sensor, and the 3rd sensor is connected to The electrical equipment, it is micro- that the first sensor, the second sensor and the 3rd sensor are also connected to the intelligence Processor control system, first solid-state switch and second solid-state switch also with the intelligent microprocessor control system It is bi-directionally connected, the intelligent microprocessor control system sends trigger pulse to first solid-state switch and second solid-state Switch to control the break-make of first solid-state switch and second solid-state switch, first solid-state switch and described second Solid-state switch by status information feedback to the intelligent microprocessor control system, the intelligent microprocessor control system also with Remote computer and interconnection switch are bi-directionally connected, and the intelligent microprocessor control system includes microcontroller, On-off signal Circuit, switching value output circuit, analog to digital conversion circuit, keyboard, liquid crystal display, power supply, Controller Area Network BUS interface with And trigger signal fiber optic interface circuits；Under normal condition, the second solid-state switch is off, when the intelligent microprocessor When control system detects the working power failure, control instruction is sent to first solid-state switch and second solid-state Switch make it that first solid-state switch disconnects and second solid-state switch turns on, while first solid-state switch and described Status information feedback is returned the intelligent microprocessor control system by the second solid-state switch.

2. pressing load seamless switching device in a kind of distribution based on solid-state switch according to claim 1, its feature exists In, first solid-state switch and second solid-state switch include main switch, auxiliary switch, thyristor switch, detection circuit, Control unit and arrester, detection circuit, the thyristor switch and the auxiliary switch are linked in sequence successively, the master Switch in parallel is connected to the both ends of the thyristor switch and the auxiliary switch, and the arrester is connected in the brilliant lock in parallel Pipe switchs and the both ends of the auxiliary switch, and the detection circuit is connected to described control unit, and described control unit is also connected with To the main switch, the auxiliary switch and the thyristor switch with to the main switch, the auxiliary switch and the crystalline substance The break-make of thyristor switch is controlled.

3. pressing load seamless switching device in a kind of distribution based on solid-state switch according to claim 2, its feature exists In the main switch and the auxiliary switch are IGBT or IGCT.

4. pressing load seamless switching device in a kind of distribution based on solid-state switch according to claim 1, its feature exists In first solid-state switch and second solid-state switch include main switch, detection circuit, control unit and arrester, institute State detection circuit to be connected with the main switch, the arrester is connected in the main switch both ends in parallel, and the detection circuit is also Described control unit is connected to, described control unit is also connected to the main switch and controlled with the break-make to the main switch System.

5. pressing load seamless switching device in a kind of distribution based on solid-state switch according to claim 4, its feature exists In the main switch is IGBT or IGCT.

6. pressing load seamless switching device in a kind of distribution based on solid-state switch according to claim 3, its feature exists In the turn off process of solid-state switch is specially：

(1) when detecting that fault current rises to 1.2 times or so of rated value, turn off the auxiliary switch, electric current start to Major loop shifts and continues to rise；

(2) as electric current shifts, the electric current in auxiliary branch is gradually reduced, when the current reduction for flowing through the thyristor switch arrives After maintaining below electric current, the thyristor switch shut-off；

(3) after the thyristor switch successfully turns off, 1.5 times of overvoltage can be born, when detecting that electric current is in auxiliary branch When zero, major loop is switched off, and shut-off voltage overshoot is born by the thyristor switch, and electric current starts to shift to arrester branch road And it is gradually reduced；

(4) die-away time of the fault current in arrester is 2ms, and when electric current is reduced to zero, solid-state switch is completed once to succeed Shut-off.

7. load seamless switching device, its feature are pressed in a kind of distribution based on solid-state switch according to claim 5 or 6 It is, the instantaneous detection that supply voltage breaks down uses three-phase d-q coordinate transform innovatory algorithms：

When there is asymmetrical voltage failure, the voltage magnitude drawn by d-q coordinate transforms is a variable quantity, and three-phase d-q Coordinate transformation algorithm can not make quantitative analysis to this variable quantity, be calculated for this using voltage signal positive-negative sequence decomposition concept and d-q After method combines, produce some changes and transform to the system three-phase voltage under abc coordinates under d-q coordinate systems, by fundamental positive sequence point Quantitative change is DC component, and negative sequence component is changed into second harmonic component, and zero-sequence component is still zero：

After system three-phase voltage under above-mentioned abc coordinates is carried out into d-q conversion, obtain：

Wherein, U_a、U_b、U_cFor the system three-phase voltage under abc coordinates, U₁For fundametal compoment, U₂For second harmonic component, U₀It is zero Sequence voltage, U_d、U_qRespectively d axles, q shaft voltages；

When ground connection or short trouble occurs, U_dAnd U_qExcept the DC component comprising positive sequence, the two frequencys multiplication exchange also comprising negative phase-sequence Component, to isolate the DC component under d-q coordinate systems, the signal after d-q is converted passes through low pass filter, the result of output As judge whether occur Voltage Drop standard, i.e.,：

<mrow> <msub> <mi>U</mi> <mrow> <mi>d</mi> <mi>q</mi> </mrow> </msub> <mo>=</mo> <msqrt> <mrow> <mn>3</mn> <mrow> <mo>(</mo> <msubsup> <mi>U</mi> <mn>1</mn> <mn>2</mn> </msubsup> <mo>+</mo> <msubsup> <mi>U</mi> <mn>2</mn> <mn>2</mn> </msubsup> <mo>)</mo> </mrow> </mrow> </msqrt> <mo>.</mo> </mrow>