RU2740796C1 - Uninterruptable dc power supply system and method - Google Patents

Abstract

FIELD: electrical equipment.

SUBSTANCE: invention relates to electrical engineering, in particular to a system and method for uninterrupted power supply of direct current using storage batteries. It is achieved by the fact that DC system supplies DC consumers with charging and rectifying units in normal mode and from accumulator batteries in emergency mode. At that, the system is mainly aimed at usage of lithium-ion accumulators as storage batteries. At the same time, the system has two independent controllers for monitoring AC networks and monitoring DC network and state of accumulator batteries.

EFFECT: technical result consists in improvement of reliability of power supply to consumers.

8 cl, 1 dwg

Description

The invention relates to power engineering, in particular, to a system and method for uninterrupted power supply of direct current using rechargeable batteries. The declared system is intended for the organization of uninterruptible DC power supply to consumers of the first and first special categories, as well as for the protection of circuits from overcurrents, monitoring and signaling of normal and emergency operating modes. The DC system provides power to DC consumers from charging and rectifying units in normal mode and from storage batteries in emergency mode.

The claimed invention can be applied to objects with a stable small DC load, where DC consumers are telemechanics, automation, signaling, communication devices and there are no high-current consumers: such as oil pumps, oil circuit breaker drives, etc. Such facilities include workshops of gas processing plants; emergency standby power plants and auxiliary power plants, closed switchgear 6 (10) kV, gas distribution stations, gas production facilities (direct current loads), gas treatment facilities, as well as other facilities with low current consumption.

The known method of uninterruptible power supply (patent RU 2355092, publ. 05/10/2009), in which it is proposed to connect renewable energy sources with storage batteries to provide through a voltage converter, during power interruptions, connect to the load an alternating voltage generator driven by an internal motor combustion in automatic mode. It is also proposed by the method to provide a given value of voltage across the load with a voltage stabilizer.

However, this method of uninterrupted power supply has the following disadvantages: it requires constant maintenance of the internal combustion engine, and it is also necessary to use expensive and climate-dependent renewable energy sources. This leads to a decrease in the reliability of an uninterrupted power supply.

The technical result of the claimed invention is to improve the reliability of power supply to consumers.

The claimed technical result is achieved by the fact that the formula contains an uninterruptible power supply system containing an automatic transfer switch 3, a battery switching unit 9, storage batteries 8, a battery monitoring and control unit 15, a monitoring and automation unit 16, a sectioning unit 14, at least main and standby power inputs 1, 2, at least two charging-rectifier units 4, 5, a charging-rectifier unit 6, 7, a battery connection unit 10, 11, and at least two DC distribution units 12 , 13. In this case, the charging and rectifier units 4, 5, the charging and rectifier unit 6, 7, the DC distribution sections 12, 13, the battery connection units 10, 11 are connected in series with each other in two circuits, and the circuits are parallel connected to the battery switching unit 9. In this case, the monitoring and automation unit 16 is connected to the seven blocks and sections by data transmission lines, except for the automatic transfer unit 3, the main input 1 and the backup input 2. The automatic transfer unit 3 is connected by data transmission lines only with the main 1 and reserve 2 power inputs.

Also, the claimed technical result is achieved by the fact that the uninterruptible power supply system is characterized by the fact that the monitoring and automation unit is configured to transmit data over a radio channel, the data transmission lines can be radio channels, the monitoring and automation unit is made with the possibility of two-way communication, and the battery is lithium ionic rechargeable battery.

Also, the claimed technical result is achieved by the fact that the automatic transfer unit and the monitoring and automation unit do not have data transmission lines between each other (completely decoupled), which in turn allows ensuring their independence and thereby increasing reliability.

Also, the claimed technical result is achieved by the method of operation of the uninterruptible power supply system, which includes the supply of alternating current from the input unit of the main or backup AC power supply to the automatic transfer unit, the supply of current from the automatic transfer input to the charging-rectifier unit, rectification of the alternating current in it and further DC supply to the DC distribution unit through the connection unit of the charging and rectifier unit and its further supply through the sectioning unit to the consumer, while part of the current from the DC distribution unit goes to maintain the battery charge through the battery connection unit to the DC distribution unit and a battery commutation unit. In this case, the state of the storage batteries is controlled by the battery control and management unit, and the state of all units of the system is controlled by the monitoring and automation unit, except for the input units of the main and backup AC power supply and the automatic transfer unit, the state of which is controlled by the automatic transfer unit itself. In this case, during power outages, the consumer is powered from the backup AC power input unit. When the power supply from the AC main power input unit is interrupted, the automatic transfer unit switches to the AC backup power input unit and continues to supply the consumer with power through the series-connected charging and rectifier unit, the unit for connecting the charger and rectifier to the DC distribution unit, and the distribution unit direct current and sectioning unit. The batteries are recharged with a portion of the outgoing current from the DC distribution unit through the battery connection to the distribution section and the battery switching unit. In case of interruptions in the supply of alternating current at all AC power inputs, the DC distribution unit and / or the sectioning unit issues a voltage drop signal, which is processed in the monitoring and automation unit, after which the monitoring and automation unit issues a signal to the battery switching unit through the monitoring unit and battery management to enable the batteries to deliver current. At the same time, the battery control and monitoring unit monitors at least the voltage of the storage batteries and, when the voltage on the storage batteries drops below the critical one, issues a signal to the battery commutation unit to disconnect the storage batteries from the circuit. When the AC supply resumes from any of the AC power input units, the charging and rectifying unit sends a signal to the monitoring and automation unit, which sends a signal to the battery switching unit through the battery monitoring and control unit to connect the batteries to the charging mode. In this case, the battery monitoring and control unit monitors the state of charge of the storage batteries and upon completion of charging the storage batteries issues a command to the storage battery switching unit to transfer the storage batteries to the buffer mode.

Also, the claimed technical result is achieved in that the method of operation of the uninterruptible power supply system is characterized by the fact that the critical voltage on the batteries, at which the batteries are disconnected from the circuit, is 2.8 V / el., And the battery control and monitoring unit controls the voltage of a single battery cell, its internal resistance and the temperature of the battery itself.

The claimed group of inventions is illustrated by a drawing, which shows:

1 - main (priority) AC power input;

2 - backup AC power input;

3 - automatic transfer unit;

4, 5 - charging and rectifying devices - AC / DC conversion (charging and rectifying units);

6, 7 - block for connecting the charger and rectifier to the DC distribution section;

8 - lithium-ion storage battery (storage batteries);

9 - battery commutation unit;

10, 11 - block for connecting the storage battery to the distribution section;

12, 13 - DC distribution block;

14 - sectioning unit (section switch);

15 - battery control and management unit;

16 - monitoring and automation unit.

The main mode of operation of the DC system is the mode of constant recharging of batteries. In this mode, fully charged batteries are connected to DC distribution units in parallel with a constantly operating charging and rectifier unit. The charging and rectifier unit provides power to the consumer of a constant load and at the same time recharges the storage batteries, compensating for their self-discharge.

The DC system goes into autonomous mode when the AC voltage on the auxiliary switchboard disappears, as well as when the charging and rectifier unit fails. In this mode, power supply to consumers of constant load and temporary, short-term, incl. jogging load, carried out by rechargeable batteries. The autonomous operation time of the DC system in conditions of complete power outage from the external power supply system and the absence of emergency or backup power is selected on the basis of a trouble-free shutdown of production in order to prevent threats to human life, explosions, fires, and equipment damage.

The equalization charge (balancing) mode for batteries is carried out automatically using the monitoring and automation unit to keep all battery cells in a fully charged state. Equalizing charge is produced by increasing the voltage, the level of which is given in the operating instructions for the batteries. The duration of the mode depends on the condition of the batteries. In equalizing charge mode, the overvoltage on the battery cells should not exceed 10% of the nominal value.

A battery check is performed to determine its actual capacity. The results of measurements of the discharge current during control discharges should be equal to the results of measurements of previous discharges. If there is only one storage battery in the DC system, the control discharge mode can be carried out only during routine maintenance or repair work of the main equipment when all consumers are disconnected.

In the maintenance mode, some consumers are disconnected and the technical condition of the equipment connected to one of the sections of the sectioning unit is monitored. The design of the DC system equipment must ensure the possibility of safe work performance.

From the main (priority) AC power input 1, electricity is transmitted through the AC line to the automatic transfer unit 3 and then along the AC line to the charger and rectifier - AC / DC 4 conversion. After that, the electricity is transmitted to the unit for connecting the charger and rectifier to the DC distribution section 6 and from there through the DC line enters the DC distribution bus 12, from where it is transmitted to the sectioning unit 14 and to the battery connection unit to the distribution section 10.

Also, from the DC distribution bus 12 through the control and monitoring line, a signal is transmitted to the monitoring and automation system 16 to control the voltage level and current consumption by consumers. The sectioning unit 14 is connected to the DC distribution bus 13 by means of a DC line, and the unit connecting the battery to the distribution section 10 is mutually connected to the unit connecting the battery to the distribution section 11 through the switching unit of the battery 9 through the DC lines. In this case, the unit for connecting the storage battery to the distribution section 11 is connected to the DC distribution bus 13 via a DC line.

When power is cut off to the main AC input 1 from the backup AC input 2 through the AC line, electricity is transmitted to the automatic transfer switch 3 and then through the AC line to the charging and rectifier device - AC / DC conversion 5, and from block 5 through the DC line to the block for connecting the charging and rectifier to the DC distribution section 7 and from there through the DC line enters the DC distribution bus 13. In this case, the DC distribution bus 13 is connected by a control line with the monitoring and automation system 16, at the same time, the monitoring and automation system 16 is mutually connected by a control line with a charging and rectifier device - an AC / DC conversion 5.

The control and management system of the storage battery 15 is connected by control lines with the monitoring and automation system 16 and the switching unit of the storage battery 9 and at the same time is mutually connected to the lithium-ion storage battery 8. Also, the control lines are connected with the automatic transfer switch 3 of the main (priority) input AC power supply 1 and a backup AC power input 2. It should be noted that the monitoring and automation system 16 with charging and rectifying devices - AC / DC converters 4, 5, as well as the battery monitoring and control system have an interconnection through the control lines 15 with rechargeable Li-ion battery 8.

The charger and rectifier unit is as follows. Each block of charging and rectifying units includes: from one to four rectifier modules, a data collection module and a control and display device that controls the rectifier modules and controls the battery charge. The control and indication device (control controller) is an independent module, completely independent of the rectifier modules. Its functions include: battery charge monitoring, insulation condition monitoring, remote alarm signaling. Rectifier modules are designed to convert AC to rectified current and supply electrical power to equipment.

The monitoring and automation unit is characterized as follows. In a DC system, discrete signals can be transmitted, characterizing its state, using relay contacts located on the control board, the signals from which are output to the terminals installed in the cabinet. Digital voltmeters and ammeters can be used to transmit information about the magnitudes of voltages and currents. One digital voltmeter per section and one digital ammeter per battery input are used. Transmission of data on the state of protective and switching devices is carried out from the outputs of the discrete signal collection modules through a special controller. The monitoring and automation unit includes control panels for monitoring and indication devices.

The direct current system converts the input alternating voltage into direct current voltage by means of the charging and rectifier units 4, 5 and distributes electrical energy to consumers in direct current circuits, and also provides operating modes for storage batteries.

Battery maintenance in the buffer mode - the buffer mode is the nominal operating mode of the charging and rectifier units. The battery charging mode is characterized by a charging current of 0.2 of the battery capacity Ah. to a voltage of 3.4 V / cell, then the batteries are charged until the current consumption drops to 5 A. The buffer mode automatically resumes after the charging mode. Balancing of storage batteries is carried out when the voltage on one of the voltage elements exceeds 3.4 V. In this case, resistors are connected in parallel with the cell, reducing the charging current of a particular cell.

The output voltage is monitored as follows. The maximum rectifier voltage setting (high voltage of the charging-rectifier units) is measured relative to the voltage of the current charging mode. Upon reaching the level of the maximum voltage setting, the charging and rectifying units are switched off. The minimum rectifier voltage setting (low voltage of the charging-rectifier units) is measured relative to the buffer mode. Upon reaching the level of the minimum voltage setting, the charging and rectifying units are switched off. Minimum battery voltage setting (battery undervoltage). When the battery voltage drops to the final voltage, this setting is blocked. Battery end-of-discharge voltage setting (low battery voltage).

Checking the continuity of the battery circuit is as follows. This function is used to check the health of the battery circuit. The check is carried out manually from the control panel of the charging and rectifying units. In the process of checking the charging and rectifier units, the output voltage is reduced to an adjustable setpoint (factory setting is 0.9 of the rated voltage), and the control unit monitors the battery voltage. If the battery voltage drops below the set point (battery protection circuit open, cable disconnected, etc.), a fault message is displayed. The CANCEL button will reset the error condition.

The automation unit is configured to perform per-feeder monitoring of the insulation resistance of the AC power input units. The DC distribution unit is also configured to monitor the insulation of outgoing lines, as well as general monitoring of the insulation condition using an insulation resistance monitoring system.

DC insulation monitoring system (outgoing lines) is designed for: measuring insulation resistance values in DC networks with voltage of 220 V and 110 V; measuring voltage imbalances in DC networks; light and sound alarms, as well as dry contact alarms when the value of the resistance of the monitored insulation goes out, the voltage level on the buses and the voltage imbalance outside the established limits; indication of the type, time and location of the accident; integration with various monitoring systems (for example, via RS485, Modbus RTU).

Automatic control and measurement of insulation resistance and pole voltage relative to the ground bus is carried out by connecting the measuring bridge to the measured network. When the resistance level drops below the adjustable settings, a feeder search occurs in order to detect a defective line.

The voltage parameters control unit (included in the block 16 on the diagram) is intended for use in operating direct current networks of switchgears of power plants and substations and can perform the following functions: monitoring the voltage value on the operating current buses; voltage ripple level control; comparison of the monitored parameters with the preset limit values; formation of an alarm in the event of controlled parameters going beyond the limit values; transmission of values of monitored parameters to the upper level of the system.

The method is carried out as follows.

In normal mode, consumers receive DC power from the main AC input through the charging and rectifier unit through circuits 1-3-4-6-12 for the first section of the DC distribution unit 12 and 1-3-5-7-13 for the second section DC distribution unit 13. In this case, the batteries 8 are in the buffer mode (the voltage of 3.34 V / el maintained by means of the charging-rectifier units), the sectional switch 14 is turned off.

In the absence of AC voltage at the main input, the automatic transfer unit switches the power supply to the reserve input. In this case, DC consumers receive power through the circuits 2-3-4-6-12 for the first section of the DC distribution unit and 2-3-5-7-13 for the second section of the DC distribution unit. In this case, the batteries are in the buffer mode (the voltage of 3.34 V / e maintained by means of the charging and rectifier units), the sectional switch 14 is turned off. When a voltage appears at the main input, the circuit returns to normal operation.

In this case, an interruption in the power supply from the mains means the absence of alternating current on any of the AC power input units 1, 2.

In the absence of AC voltage at both AC inputs 1, 2, the DC distribution unit 12 and / or 13 and / or the sectioning unit 14 issues a voltage drop signal, which is processed in the monitoring and automation unit 16. In this case, DC consumers receive power from the storage batteries along the circuit 8-9-10-12 for the first section of the DC distribution unit and 8-9-11-13 for the second section of the DC distribution unit. In this case, the batteries are in the discharge mode. When the batteries are discharged to a critical value (2.8 volts / cell), the battery monitoring and control unit 15 issues a command to the battery switching unit 9 to disconnect the batteries from consumers, and the discharge of the batteries stops. Consumers lose their food. Local and remote alarms are triggered in the monitoring and automation unit 16, indicating that the batteries 8 are discharged.

In the absence of AC voltage at all AC power inputs, the consumer is powered by batteries. In this case, the DC distribution unit and the sectioning unit are equipped with sensors that are configured to transmit a voltage drop signal.

When the AC voltage is restored at any of the inputs, the monitoring and automation unit 16 instructs the charging and rectifier units to switch to the charging mode (voltage 3.4 V / cell). DC consumers receive power through the circuits in accordance with the normal operation mode, but at the same time, the batteries are additionally charged through two circuits (an example is considered below when restoring the main input) 1-3-4-6-12-10-9-8 and 1- 3-5-7-13-11-9-8. When the state of charge reaches 90% (criterion - the voltage of the batteries reached 3.4 V / cell, the current in the battery circuit dropped to 5 A), the monitoring and automation unit instructs the charging and rectifier units to switch to the buffer mode (voltage 3.34 V / e).

If one of the charging and rectifying units fails, DC consumers of both sections of the DC distribution unit receive power from the working charging and rectifying unit along the circuit (an example is considered when unit 5 fails) 1-3-4-6-12 for the first sections of the DC distribution block and 1-3-4-6-12-10-9-11-13 for the second section of the DC distribution block. When the charging-rectifier units are restored to their normal state, the circuit returns to its original state, i.e. into normal operation.

Sectioning unit 14 is designed to organize a repair jumper between the first and second sections of DC distribution units 12, 13 for servicing charging-rectifier units 4, 5, as well as blocks for connecting charging-rectifier units to a DC distribution unit 6, 7 and batteries 8 to DC distribution units 12, 13. For example, to service units 5, 7, 11, it is necessary to turn on unit 14. At the same time, DC consumers of the second section of DC distribution unit 13 receive power through the circuit 1-3-4-6-12- 14-13. After completion of the service, the circuit must be returned to its original position, i.e. into normal operation.

The battery control and management unit 15 is designed for continuous monitoring of the battery parameters, giving a signal to the battery switching unit 9 to disconnect the batteries from the network in the event that the controlled parameters (voltage, temperature, current, etc.) go beyond the set values, and also to provide battery balancing. In this case, the state of the battery means the voltage of the battery as a whole and the voltage of a single cell, as well as the internal resistance and temperature of the battery itself, etc.

The monitoring and automation unit 16 is designed to control the operating modes of the charging and rectifier units 4, 5, continuous control over the parameters of the DC system, local and remote signaling about the operating modes of the system, as well as the transfer of controlled parameters through standard information interfaces, protocols.

The monitoring and automation unit 16 is configured to transmit parameters such as: battery parameters (current, voltage, charge / discharge mode, etc.); load parameters (current, voltage, power consumption, etc.); general system failure.

Claims (19)

1. An uninterruptible power supply system containing an automatic transfer unit, a battery switching unit, batteries, a battery monitoring and control unit, a monitoring and automation unit, a sectioning unit, at least the main and backup power inputs, at least two charging and rectifying a block, a connection block for a charging-rectifier unit, a battery connection block, as well as at least two DC distribution sections, characterized in that charging-rectifier blocks, charging-rectifier block connection blocks, DC distribution sections, battery connection blocks are connected in series with each other in two circuits, and the circuits are connected in parallel to the battery switching unit, while the monitoring and automation unit is connected to all units and sections by data transmission lines, except for the automatic transfer unit, the main input and the backup input, The automatic transfer unit is connected by data transmission lines only with the main and reserve power inputs. 2. An uninterruptible power supply system according to claim 1, characterized in that the monitoring and automation unit is configured to transmit data over a radio channel. 3. An uninterruptible power supply system according to claim 1, characterized in that the data transmission lines can be radio channels. 4. The uninterruptible power supply system according to claim 1, characterized in that the monitoring and automation unit is made with the possibility of two-way communication. 5. An uninterruptible power supply system according to claim 1, wherein the storage battery is a lithium-ion storage battery. 6. The method of operation of the uninterruptible power supply system according to claim 1, including the supply of alternating current from the input unit of the main or backup AC power supply to the automatic transfer unit, supply of current from the automatic transfer switch to the charging and rectifier unit, rectification of alternating current in it and further supply of direct current to the DC distribution unit through the connection unit of the charging and rectifier unit and its further supply through the sectioning unit to the consumer, while part of the current from the DC distribution unit goes to maintain the battery charge through the connection unit the battery to the DC distribution unit and the battery switching unit, characterized in that the state of the batteries is controlled by the battery control and management unit, and the state of all system units is controlled by the monitoring and automation unit, with the exception of the input units of the main and backup AC power supply and the automatic transfer unit, the state of which is controlled by the automatic transfer unit itself , wherein in case of power outages from the mains, the consumer is powered from the AC backup power input unit, at the same time, when the power supply from the AC main power input unit is interrupted, the automatic transfer unit switches to the AC backup power input unit and continues to supply the consumer with power through the series-connected charging and rectifier unit, the unit for connecting the charger and rectifier to the DC distribution unit, DC distribution unit and sectioning unit, in this case, the rechargeable batteries are recharged with a part of the outgoing current from the DC distribution unit through the unit for connecting the batteries to the distribution section and the battery commutation unit, in the event of interruptions in the AC supply at all AC power inputs, the DC distribution unit and / or the partitioning unit issues a voltage drop signal, which is processed in the monitoring and automation unit, after that, the monitoring and automation unit issues a signal to the battery commutation unit through the battery monitoring and control unit to turn on the batteries in the current delivery mode, in this case, the battery control and monitoring unit monitors at least the voltage of the storage batteries and, when the voltage on the storage batteries drops below the critical value, issues a signal to the battery commutation unit to disconnect the storage batteries from the circuit, at the same time, when the AC supply resumes from any of the AC power input units, the charging and rectifier unit sends a signal to the monitoring and automation unit, which sends a signal to the battery switching unit through the battery monitoring and control unit to connect the batteries to the charging mode, In this case, the battery control and management unit monitors the state of charge of the storage batteries and upon completion of charging the storage batteries issues a command to the storage battery switching unit to transfer the storage batteries to the buffer mode. 7. The method of operation of the uninterruptible power supply system according to claim 6, characterized in that the critical voltage on the storage batteries, at which the batteries are disconnected from the circuit, is 2.8 V / el. 8. Method of operation of the uninterruptible power supply system according to any one of paragraphs. 6 or 7, characterized in that the battery control and monitoring unit monitors the voltage of a single battery cell, its internal resistance and the temperature of the battery itself.

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