CN210780230U

CN210780230U - Switch device for switching high power from off-grid to grid-connected

Info

Publication number: CN210780230U
Application number: CN201921907836.4U
Authority: CN
Inventors: 杜建林; 孙大伟; 唐雅萍; 张洪涛; 丁伯磊
Original assignee: BEIJING IN-POWER NEW ENERGY CO LTD; Langfang In Power Electric Co ltd; BEIJING IN-POWER ELECTRIC CO LTD
Current assignee: BEIJING IN-POWER ELECTRIC Co.,Ltd.; LANGFANG IN-POWER ELECTRIC Co.,Ltd.
Priority date: 2019-11-07
Filing date: 2019-11-07
Publication date: 2020-06-16
Anticipated expiration: 2029-11-07

Abstract

The utility model discloses a switching device that is used for high-power to change from net to being incorporated into power networks, the device includes control module, power module, collection module, execution module, protection module, communication module. The device adopts the modularized design theory, and the design has single chip microcomputer control's control panel, is equipped with sufficient input/excision order DI, on-off state DO, can utilize according to actual demand is nimble, under the condition that satisfies actual demand, furthest's avoiding unnecessary cost extravagant. The utility model discloses extend large capacity energy storage inverter, realize that the power consumption is incessant, the function of the seamless switching of power supply network. A soft grid-connected loop is arranged, rapid input response is achieved through a series resistor of a contactor with small capacity and a fuse, and the soft grid-connected loop is used for converting the active inverter from off-grid to grid-connected operation.

Description

Switch device for switching high power from off-grid to grid-connected

Technical Field

The utility model belongs to the technical field of power transmission and transformation, can switch energy supply through remote control and switch, especially be used for adopting the little electric wire netting of dc-to-ac converter, converter to switch to the switching device who is incorporated into the power networks the state from the off-grid state.

Background

With the development of power electronic technology, large-capacity battery energy storage systems, micro-grid solar power generation systems and the like are put into the market on a large scale. The subject of how to improve the automation and intelligence of a power supply system in a three-phase AC power supply system follows.

For a multi-power supply system, due to the difference of the value assignment, the frequency and the phase of two power supplies, the parallel connection of voltage sources has the problem of circular current and the like; only one power supply is required to output at the same time, and other power supplies are in a standby state. When power switching is needed, the initial power supply needs to be manually cut off, and the standby power supply needs to be put into use. The method for switching the power supply wastes time and labor and inevitably has power failure time.

In addition, when a system is tripped due to a fault of a load, even if the power is supplied by the dual power sources, the power supply cannot be recovered before the fault is repaired. When the system power supply is switched forcibly, the risk of an accident is also increased.

SUMMERY OF THE UTILITY MODEL

To the problem in the background art, the utility model provides a switching device that is used for high-power to change from net to being incorporated into the power networks. The switching device has the following characteristics:

1. the uninterrupted power supply is used for controlling the power supply, so that unmanned management is realized;

2. the electric energy metering is realized through a metering device in the device; the metering device belongs to the acquisition module, and the control module can read the electric energy data in real time and upload the electric energy data through the communication module;

3. the embedded design is compatible with various communication modes, so that background system management is facilitated;

4. the seamless switching of the power supply can be realized through a high-capacity energy storage inverter;

5. by monitoring the power utilization condition of each branch in real time, the fault monitoring function can be realized, and the fault circuit can be timely removed.

In order to achieve the above purpose, the technical solution of the present invention is as follows:

a switching device for high-power off-grid to on-grid switching comprises a control module, a power supply module, an acquisition module, an execution module, a protection module and a communication module, wherein the control module adopts an STM32 series single chip microcomputer as a main control chip, acquires internal information of the device in real time and uploads the internal information to a background through the communication module; the power supply module is externally connected with a 220V power supply and provides an isolated 24V control power supply for the whole device; the acquisition module comprises a voltage sampling circuit and a current sampling circuit which are all isolated, and is used for acquiring electric energy information of the main loop and transmitting the electric energy information to the control module; the control module follows the electric energy information provided by the acquisition module and controls the flow direction of the electric energy through the execution module; the control module is a contactor, a relay and a controlled silicon which are contained in the device; the communication module is connected to the control module and is used for expanding information interaction of uplink and downlink equipment and performing remote control; the protection module is connected to the control module and comprises current protection and voltage protection.

As a preferred scheme, the control module adopts an embedded type autonomously developed control panel, and the control module internally comprises 4 ADC chips with 8-path input, so that ADC sampling is conveniently expanded; reserving 30 paths of IO (input 20 paths and output 10 paths) for controlling the breaking/closing of the silicon controlled rectifier and the load switch, the feedback of the switch state and the like; interfaces for smoke alarm, fire alarm, temperature and humidity detection and the like are designed; communication interfaces such as 485, LAN, CAN, optical fiber and the like are reserved, and communication with a background control terminal is facilitated.

As a preferred scheme, the power supply module adopts an intelligent alternating current-direct current selection module, and an AC input interface and a DC input interface are designed; the power supply mode can be selected automatically, and whether the two power supplies are normal or not can be monitored in real time; when one path has a fault, an alarm signal is uploaded and automatically switched to a loop with normal power supply.

Preferably, the communication module comprises LAN, 485 and CAN communication.

As a preferred scheme, the voltage sampling circuit has three modes, namely a current-limiting resistor-isolation transformer mode, a direct-current sampling Hall mode and a differential sampling mode; the three modes can be configured according to practical application;

the current sampling circuit has three modes, namely a mutual inductor mode, a current Hall mode and a current divider mode; the three modes can be configured according to practical application.

The phase modulation function of off-grid to on-grid conversion comprises two modes, namely communication phase code and real-time voltage sampling.

As a preferable scheme, metering devices are arranged in the voltage sampling circuit and the current sampling circuit, and the control module reads electric energy data on the metering devices in real time and uploads the electric energy data through the communication module.

The metering device is an optional item, the metering device does not influence the function of the whole device, when a customer needs to remotely read the electric energy metering value in the background, two methods are provided, one is to directly read the data of the control module through the communication module to be used as the metering value; however, the value is calculated by the control module, and when the customer requires to use the electric energy meter for metering, the communication interface of the electric energy meter can be intercepted to the communication module of the device, and the communication interface is forwarded to the background through the control module.

The beneficial effects of the utility model reside in that:

the utility model discloses in, the major loop uses the circuit breaker of live working as main switching device, realizes the circulation of heavy current. This device adopts the modularized design theory, and the design has single chip microcomputer control's control panel, is equipped with sufficient input/excision order DI, on-off state DO, can utilize according to actual demand is nimble, under the condition that satisfies actual demand, furthest's avoiding unnecessary cost extravagant. The utility model discloses can extend large capacity energy storage inverter, realize that the power consumption is incessant, the function of the seamless switching of power supply network. A soft grid-connected loop is arranged, rapid input response is achieved through a series resistor of a contactor with small capacity and a fuse, and the soft grid-connected loop is used for converting the active inverter from off-grid to grid-connected operation. The device CAN support 485, CAN, LAN and other network communication according to requirements, and CAN realize remote control. The device has the functions of analog quantity sampling and temperature detection, can detect the states of the inside of the module and the power grid in real time, and can realize the function of electric energy metering.

The utility model is compatible with various types of circuit breakers, contactors, load switches, semiconductor devices and the like, and can be designed into modules, JP cabinets or electrical cabinets according to the actual capacity, the number of power supplies and loads; the enough space has guaranteed electric property, security and reliability, has promoted maintainability.

The utility model discloses compatible multiple communication mode to background control system's design. A scheme is provided for unmanned and automatic electric energy management; may be referred to some extent as a "power router".

Drawings

FIG. 1 is a main circuit diagram for a high power live grid tie diverter switch;

FIG. 2 is a circuit diagram of a soft start loop for a high power live grid tie switch;

FIG. 3 is a power supply circuit diagram for a high power live grid transfer switch;

fig. 4 is an overall topological diagram for a high-power live grid-connected change-over switch.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and embodiments.

The utility model provides a be used for seamless auto-change over device of electric energy divide into control module, power module, collection module, execution module, protection module, communication module, as shown in figure 4.

Control module

The control module adopts an STM32 series single chip microcomputer as a main control chip, collects the internal information of the device in real time and uploads the internal information to the background through a communication interface; in addition, the control module is divided into 3 levels according to resources and functions.

The first stage supports electric energy metering, device information (including IO, environment temperature and humidity and the like) information collection and uploading and the like;

the second stage is that on the basis of the first stage, the remote control power supply switching function is expanded, the unmanned standby power supply switching function can be realized, and the automatic power-off switching program can be set manually or according to the requirement;

and in the third stage, on the basis of the second stage, the seamless switching function is expanded, and a high-power energy storage converter is required to be expanded to serve as electric energy support for system switching power-off time.

Power supply module

The power supply module is provided with an AC power supply interface and a DC power supply interface; in order to ensure the uninterrupted power control function, an AC power supply interface needs to be connected to an uninterrupted power supply, and a DC power supply interface needs to be connected to a direct-current power supply (an energy storage battery); the power supply module preferentially selects the AC power supply interface to supply energy, and sets the DC interface as a standby power supply for reducing the charge-discharge utilization rate of the battery.

Acquisition module

The acquisition module is provided with sufficient isolated ADC sampling interfaces in the main control design, and acquires and monitors input voltage and current of each power supply. The power supply and power consumption conditions of the system can be monitored in real time; wherein: the current sampling can select two sensors of a Hall sensor and a mutual inductor.

(for the active inverter interface, a Hall sensor is used, and the direct current component can be monitored in real time).

Execution module

The execution module is designed differently for different control levels, and specifically comprises the following steps:

for the 'first-stage' master control, the power supply condition of the system is only acquired, so that no special requirement exists, a molded case circuit breaker, a contactor and the like can be used, and the power supply needs to be manually switched when the power is cut off; the execution module adopts a molded case circuit breaker, a contactor and the like as a main loop and is used for closing/breaking the connection between the power system and the load; because the first-level master control does not support remote control, the power grid switching needs to be carried out manually on site; in addition, the acquisition function is to acquire the electric energy information to the control module in real time through an isolated sampling channel, and the control module transmits the electric energy information to the background in real time through the communication module;

for the second-level main control, a contactor or a circuit breaker operated in a charged mode is recommended, and remote switching can be performed through a background; the second-level master control supports remote live operation, so that the power supply module must be provided with a UPS or a control power supply loop independent of a power utilization network to ensure that the control power is uninterrupted; in addition, because a remote electric energy switching function is supported, a relay, a contactor or a breaker with an electric operation is needed, and a control line of the relay, the contactor or the breaker needs to be connected to a response IO port of the control module to realize remote control;

for the third-level master control, a large-capacity energy storage inverter and an off-grid switch need to be expanded for electric energy switching. The third-level master control is realized because the electric load needs uninterrupted high-quality electric energy without jitter; the power supply system has the conditions of fluctuation, failure, power failure and the like; at this time, a high-power energy storage inverter is needed for continuously providing load electric energy after the system 1 is powered off to ensure that the load is uninterrupted, so that the inverter is equivalent to an independent power supply system and belongs to a parallel connection relation with an actual power supply system through a contactor; when the system 2 is about to be connected into a power grid, due to impulse voltage, current and the like existing in grid connection, soft grid connection needs to be carried out through a soft start module, after the soft grid connection is successful, the system 2 is formally connected into the power grid, and the high-power energy storage inverter is cut off;

protection module

The protection module is divided into hardware protection and software protection according to protection logic; the conventional protection function is shown in table 1. And an input DI node is reserved, and the protection function can be expanded according to requirements.

Software protection, which depends on the acquisition module, the program judges the electric energy information uploaded by the acquisition module, the protection value can be set more flexibly, but the protection action is slower due to filtering of software acquisition and delay of program operation;

the hardware protection is arranged in the acquisition module, the conditioned analog quantity information is compared with reference voltage through a comparator, when the hardware protection acts, high and low levels are transmitted to pins of a control chip in the control module, and a main control program adopts an edge triggering mode, acts quickly, is limited by early requirements, is determined when leaving a factory and cannot be changed;

the device is connected in series with a main circuit of the device, and when the software protection and the hardware protection are unsuccessful, the fusible core is fused, and a plastic shell break-off port breaks the circuit to ensure that the fault range is not expanded;

the protection response speed is from slow to fast, the protection threshold value is from low to high, the fault severity is from low to high, and the priority is from low to high;

TABLE 1 conventional protection function

Serial number	Hardware protection function	Serial number	Software protection function
				1	Overcurrent protection	1	Overcurrent protection
2	Overvoltage protection	2	Reactive power over-high protection
				3	Under-voltageProtection of	3	Harmonic content overtop protection
4	Controlling power down protection	4	Overload protection
				5	Overload protection	5	Protection against fire
6	Lightning surge protection	6	Smoke protection
				7	Live lockout protection	7	Surge protector fault protection
8	Fuse protection	8	Breaking/closing fault protection

Communication module

The communication module is provided with LAN, 485 and CAN communication, and CAN expand an optical port according to requirements. The communication protocol adopts a standard modbus protocol, and provides a comprehensive point table which can be selectively used by a background system.

And (3) reserving 30 isolated IO (DI 20 paths and DO 10 paths) channels and adopting hard node control for signals with higher communication speed requirements (such as grid connection control signals and off-grid control signals) limited by the delay uncertainty of the communication protocol.

The control method for live grid-connected switching comprises the following steps:

SS01 fault circuit cutting function

When the system power supply abnormality (mainly shown as overcurrent, harmonic or reactive power content overhigh, load over-unbalance and the like) is detected, the connection between the system power supply abnormality and the alternating current bus is cut off in time. And automatically switching the power supply to the standby power supply system.

When the abnormal power of a certain load is detected, the connection between the load and the bus is cut off in time. The pressure of the power grid is reduced, and the power demand of the fault-free branch is guaranteed to the maximum extent.

Through the flexible and controllable emergency response, intelligent electric energy management is realized.

SS02, system 'seamless' handover function

When the system 1 is powered on, the energy storage device is in a hot standby state, and when the system 1 breaks down, the connection between the bus and the system 1 is cut off immediately; the energy storage inverter is used as a temporary power supply, and electric energy is continuously output according to the frequency, the amplitude and the phase of the system 1. At the moment, the phase modulation instruction is issued, and the output of the energy storage inverter is adjusted to be looked at the system 2.

And then the soft start loop is conducted by triggering the controlled silicon. And after the soft start is successful, closing the main power supply of the system 2 to complete the switching. And the energy storage device is charged, and enters a hot standby state after charging is finished so as to prepare for next system switching.

The first embodiment is as follows:

referring to fig. 1, the present invention includes a whole switch system, which is two system inputs, and one of the high capacity energy storage inverter is used as the power support for the "power off time". A plurality of load circuits are inserted into the power grid;

the switch system, namely the execution module, comprises a relay, a contactor, a load switch, a silicon controlled rectifier (soft start loop) and other switch devices;

and system voltage sampling is arranged before each input switch. At the bus position, bus voltage sampling is arranged; sampling voltage to acquire frequency, phase and amplitude of three-phase voltage;

setting current sampling sensors (mutual inductors/current Hall, Hall sampling is set at the position of an energy storage inverter) at the positions of the input switch and the output switch; testing the energy flow direction in real time;

the present example is an uninterruptible power supply diverter switch, i.e. the load power is not interrupted. Therefore, all loads are in a closing stage, the system 1 supplies power, and the KM1 is in a closing state; the energy storage device is used as 'power off time electric energy support' and is in a hot standby device.

When the system 1 is powered off, the control module monitors that the system 1 is powered off; the incoming line switch KM1 of the 'system 1' is switched off immediately; meanwhile, the energy storage device outputs according to the frequency, the phase and the amplitude of the original system 1, so that the load energy supply is ensured;

and then, comparing the voltage sampling information of the system 2 with the bus voltage sampling information, and issuing a phase modulation command to the energy storage device. Gradually adjusting the frequency, the phase and the amplitude to a working state synchronous with the system 2 through the phase modulation function of the energy storage device, and then closing the connection between the system 2 and the bus; at the moment, the energy storage device is switched into a hot standby mode, and the energy storage battery is charged for the next switching; thereby realizing the function of seamless switching of the load;

in the above process, the capacity of the energy storage battery is limited by the load size and the phase modulation time of the energy storage device. Therefore, on the basis of excellent phase modulation performance of the energy storage device, the battery capacity can be properly reduced;

example two:

in the first embodiment, limited to the performance of the energy storage inverter, after phase modulation, there may be some errors between the actual voltage of the bus and the "system 2" in frequency, phase and amplitude. Therefore, a soft start loop shown in fig. 2 needs to be incorporated at the system voltage access switch.

When the system 1 is disconnected, the energy storage inverter only needs to calculate a modulation wave according to the original frequency, phase and amplitude value and continuously outputs electric energy; the switching action involved is only KM1 opening.

When the system 1 is disconnected and the load electric energy is provided by the energy storage inverter, the energy storage inverter works in an off-grid mode to provide three-phase 380V alternating-current voltage, and at the moment, the energy storage inverter is equivalent to a voltage source; when the system 1 or the system 2 supplies power, the energy storage inverter is equivalent to a current source (only the output current at the moment is 0); therefore, at the moment of off-grid-connection, the switching process of a voltage source-current source is involved;

the off-grid and on-grid processes have higher requirements on control speed, so a hard contact control mode is adopted. The execution unit adopts a thyristor, and the thyristor has higher cost and higher cost when the capacity is larger. Therefore, the small-capacity system adopts finish rolling pipe to control the power supply of the system 1 and the system 2, and the large-capacity system needs to select a soft start loop as shown in the figure 2;

when the phase modulation of the energy storage inverter is finished, firstly, the soft switch is closed, and at the moment, the slight difference between the bus voltage and the system 2 is borne by a high-power soft switch resistor; meanwhile, the energy storage inverter still works in a voltage control mode, and the circulating current between the voltage of the energy storage inverter and the system 2 is limited by the soft start resistor. And then, the energy storage inverter device is switched from voltage control to current control, and the energy storage inverter device still maintains the output capacity before switching to output. The load electric energy is still provided by the energy storage inverter. Finally, the main switch KM2 of the "system 2" is closed, and the output of the energy storage inverter device is gradually reduced to 0. And then, carrying out small-capacity charging, and after the battery is fully charged, recovering the energy storage inverter to a hot standby state.

By the method, seamless switching of the system electric energy is realized, and the system voltage is not discontinuous for the load.

Example three:

the utility model discloses in, control electricity adopts and supplies with as shown in "figure 3", and wherein the AC side produces DC24V through power module and supplies with control module, and the electric potential location is energy storage inverter device DC side energy storage battery to the direct current side of getting. And the power supply control module preferentially selects a 24V power supply generated by power supply of the alternating current side, and automatically switches to the energy storage battery of the direct current side for power supply when the alternating current side cannot provide electric energy.

As can be seen from the description of the first embodiment and the second embodiment, the energy storage battery works in a full-charge state for a long time, so that the scheme can realize the purpose of controlling the power supply to be uninterrupted.

The scheme of this patent to realizing electric energy control lies in here:

(1) remote electric energy monitoring and electric energy metering are carried out, and electric energy information can be transmitted to a background in real time for detection and statistics;

(2) the remote power supply and the load cutting and input can be realized; manpower is saved to carry out system switching, and the work of power failure and power transmission of the load is carried out;

(3) the device is flexible and changeable, is used as an interface of a power supply system, and can be used for multi-system expansion according to requirements;

as an interface of an electric load, a multi-way switch can be arranged according to actual conditions;

(4) on the basis of "(1)", "(2)", "(3)", when a background remotely detects abnormal problems of a certain load (such as excessive power, overcurrent, overvoltage, reactive overrun, harmonic overrun and the like), the load can be remotely cut off so as to ensure the normal work of a tidying power supply loop; real-time monitoring and real-time protection of the system are realized;

(5) in the existing power supply mode of two systems (a main system and a standby system) in the market, when the system 1 fails, the system 1 needs to be cut off firstly, then the power supply system is manually switched to the standby system, and the power failure time is inevitably existed at the time;

after the high-power energy storage inverter is expanded, when a system 1 fails and has power failure, the high-power energy storage converter is immediately put into operation to provide electric energy for a load;

then, the high-power energy storage converter performs phase modulation by taking the system 2 as a reference;

under the condition of being supported by an interface of the energy storage converter (an analog quantity sampling channel is enough), the amplitude, the frequency and the phase of the reference voltage of the system 2 are obtained by adopting a voltage real-time sampling mode; when the analog quantity sampling interface of the energy storage converter is insufficient, a communication 'relative code' mode is needed, and the device transmits the voltage of the system 2 and the situation of the electric compaction of the microgrid to the energy storage converter in real time for adjusting the phase, amplitude and frequency of the voltage of the microgrid;

after finishing phase modulation, closing a 'soft start' switch of the system 2;

after the soft start is finished, the switch of the system 2 is formally closed, the high-power energy storage device can stop, and the energy storage battery can be immediately charged for next electric energy switching;

through the process, when the system is switched, no power failure time exists for the electric load, and a user cannot feel the influence of power failure.

In addition, it should be emphasized that the technical solutions adopted in the present application to solve the technical problems are based on hardware and known software, that is, the software related to the present application belongs to the prior art.

It should be understood that the detailed description and specific examples, while indicating the invention, are given by way of illustration only. The present invention is not limited to the above embodiments, but may be modified in various ways.

Claims

1. A switching device for high-power off-grid to grid connection comprises a control module, a power supply module, an acquisition module, an execution module, a protection module and a communication module, and is characterized in that the control module adopts an STM32 series single chip microcomputer as a main control chip, acquires internal information of the device in real time and uploads the internal information to a background through the communication module; the power supply module is externally connected with a 220V power supply and provides an isolated 24V control power supply for the whole device; the acquisition module comprises a voltage sampling circuit and a current sampling circuit which are all isolated, and is used for acquiring electric energy information of the main loop and transmitting the electric energy information to the control module; the control module follows the electric energy information provided by the acquisition module and controls the flow direction of the electric energy through the execution module; the communication module is connected to the control module and is used for expanding information interaction of uplink and downlink equipment and performing remote control; the protection module is connected to the control module and comprises current protection and voltage protection.

2. The switching device for high-power off-grid to on-grid conversion according to claim 1, wherein the control module adopts an embedded control board, and the control board internally comprises 4 '8-way' input ADC chips; comprises 30 paths of IO; comprises a smoke alarm, a fire alarm and a temperature and humidity detection interface; including 485 LAN, CAN, optical fiber communication interface.

3. The switching device for high-power off-grid conversion network according to claim 2, wherein the 30-way IO comprises 20 input ways and 10 output ways.

4. The switching device for high-power off-grid to on-grid conversion according to claim 1, wherein the power supply module adopts an intelligent AC/DC selection module, and comprises an AC input interface and a DC input interface.

5. The switching device for high-power off-grid to on-grid conversion according to claim 1, wherein the communication module comprises LAN, 485, CAN communication; reserving 30 isolated IOs.

6. The switching device for high-power off-grid conversion network according to claim 5, wherein the 30 IO lines comprise 20 input lines and 10 output lines.

7. The switching device for high-power off-grid to on-grid conversion according to claim 1, wherein the voltage sampling circuit comprises three modes, namely a current-limiting resistor-isolation transformer mode, a direct-current sampling Hall mode and a differential sampling mode;

the current sampling circuit comprises three modes, namely a mutual inductor mode, a current Hall mode and a current divider mode.

8. The switching device for high-power off-grid to grid connection according to claim 1, wherein metering devices are arranged in the voltage sampling circuit and the current sampling circuit, and the control module reads electric energy data on the metering devices in real time and uploads the electric energy data through the communication module.