CN202197148U - Direct current power supply system for substations - Google Patents

Abstract

The utility model provides a DC power supply system for substations. The system includes a centralized monitoring module, a DC operation power supply module, a UPS power supply module, an inverter power supply module, a communication power supply module and a lithium iron phosphate energy storage module. Each module of the DC power system is connected to the common DC bus through a relay switch, and each module is connected to the common DC bus in parallel with multiple sub-modules to realize redundant backup. The modules of the DC power supply system are all connected to the centralized monitoring module through the CAN communication bus. The centralized monitoring module collects the operating status information of each module, and conducts unified management of each module of the system, and realizes shallow charging and shallow discharging of the battery through intelligent coordinated control. , and realize the online automatic maintenance of the battery. The utility model has the advantages of high system reliability, strong impact load resistance, maintenance-free, small footprint, energy saving and environmental protection, and the intelligent coordinated control method improves the service life and performance of the battery.

Description

A kind of DC power supply system for substation

technical field

The utility model relates to an electric power supply system, in particular to a DC power supply system for substations based on lithium iron phosphate batteries, which is suitable for online automatic maintenance-free control of DC power supply systems for substations. The system is mainly used in power plants, hydropower stations and industrial Various substations or switch stations such as enterprise power distribution can also be extended to DC power systems for communication base stations or buildings.

Background technique

The DC operating power supply, UPS power supply, inverter power supply, and communication power supply in the existing station DC power supply system are all equipped with their own backup batteries, and the batteries basically use valve-regulated lead-acid batteries. It has been significantly improved, but there are still defects such as low energy density and power density, narrow operating temperature range, low charge and discharge efficiency, and short service life. Moreover, lead has been included in the restricted scope of the six hazardous substances. The actual situation we are facing now is that both sealed lead-acid batteries and valve-regulated lead-acid batteries have serious acid pollution and lead pollution. With the popularization of unattended substations and urbanized substations, as well as the substantial improvement of the intelligence, digitalization and automation level of the DC system of the substation, higher requirements are put forward for the volume, performance, safety and maintenance-free of the DC system battery used in the substation. requirements.

As far as the applicant knows, lithium iron phosphate batteries have the characteristics of long cycle life, strong shock load resistance, high specific energy, high charge-discharge rate, wide operating temperature range, no memory effect, maintenance-free, long life, and environmental protection. It is widely used in electric vehicles, electric bicycles, electric tools and other fields. However, in the substation DC power supply system, due to the requirement of uninterrupted power supply, the battery is in the floating state for a long time, resulting in a significantly shortened service life of the battery. At the same time, the maintenance of traditional lead-acid batteries is still carried out by manual intervention, which needs to be modified to adapt to the advanced working environment and requirements.

Chinese patent document (publication number CN101752616 A) disclosed "on-line maintenance method for battery capacity of substation DC operating power supply", which consists of steps of detection, replacement, water replenishment and charging: first detect and replace the battery with low capacity, and replace it After supplementing the battery with water to the height of the plate, add water according to the structural capacity at a ratio of 500ml/500Ah to 1500ml/500Ah, then charge the battery, adjust and calibrate the floating charge voltage to 98.18% to 101.82% of the rated voltage, so that the battery The final reserved capacity shall not be lower than 80% of the structural capacity. The "DC power screen intelligent monitor and control method" disclosed in the Chinese patent document (CN1588255 A) is used in substations, power plants, factories, airports and other places where DC screens are used, and is used in substations above 10KV and any capacity. The complete set of equipment in the power plant needs to solve the centralized control, detection, protection, alarm and display of the DC power cabinet in the DC panel system. The method includes: the technical fields of single cell voltage detection of the battery pack, insulation monitoring technology, multi-serial port expansion technology and the like. The applicant believes that the aforementioned "On-line Maintenance Method for Battery Capacity of DC Operating Power Supply in Substation" and "Intelligent Monitor and Control Method for DC Power Panel" both have the problem of low maintenance automation.

Contents of the invention

The purpose of this utility model is: the utility model applies the lithium iron phosphate battery to the DC power supply system for substations, which solves the problems of large battery footprint and serious waste pollution in the existing DC power supply system for substations. At the same time, it adopts intelligent coordination The control method solves the problems of long-term floating charge of lithium iron phosphate battery, shortening service life and real automatic online maintenance.

The technical scheme adopted by the utility model is: A DC power supply system for a substation, including a DC operating power supply module, a UPS power supply module, an inverter power supply module, a communication power supply module, a lithium iron phosphate energy storage module and a centralized monitoring module. in:

The lithium iron phosphate energy storage module is connected to the DC bus through the first relay switch KM1, and the DC operation power supply module, UPS power supply module, inverter power supply module, and communication power supply module are connected to the DC bus through the second relay switch KM2 and the second relay switch KM2 respectively. The third relay switch KM3, the fourth relay switch KM4, and the fifth relay switch KM5 are connected to the DC bus and share the lithium iron phosphate energy storage module; the centralized monitoring module realizes information communication with each module through the CAN communication bus, And supply power through the DC bus; each module in the DC power system can realize redundant backup of the system by increasing the number of modules connected in parallel to the DC bus;

The lithium iron phosphate energy storage module is composed of a lithium iron phosphate battery pack connected in parallel with a battery management system, and the lithium iron phosphate battery pack is a battery pack composed of a plurality of lithium iron phosphate batteries connected in parallel and then connected in series.

The above-mentioned DC power supply system for substations is characterized in that the DC power supply system adopts a common DC bus connection mode, and each module can realize plug-and-play online operation, and the system can automatically remove faulty functional modules, and The faulty module can be replaced online without affecting the normal operation of the system.

The above-mentioned DC power supply system for substation is characterized in that the battery management system is composed of a liquid crystal screen, a main control module and a plurality of acquisition/balance modules, the battery management system is directly connected with the lithium iron phosphate battery pack, and the acquisition module collects The voltage of the single battery and the voltage, current and temperature information of the battery pack. The main control module processes the collected data with some predetermined algorithms to determine the working status of the battery. The working status of the battery is displayed in real time through the LCD screen on the battery management system. And transmit it to the centralized monitoring system through the CAN bus, and the centralized monitoring system controls the charger of the DC operating power module.

The above-mentioned DC power supply system for substation is characterized in that the centralized monitoring module is composed of a microcontroller, a memory, an Ethernet communication interface of an intelligent substation, an industrial control touch screen, multiple CAN buses, an RS485 bus and a wireless communication bus, The microcontroller is interconnected with the memory through the parallel bus, SPI bus and I2C bus; the industrial control touch screen realizes the communication connection with the microcontroller through the Ethernet or CAN bus interface; the microcontroller realizes the communication connection with the substation remote monitoring system through the Ethernet interface , and complies with the IEC61850 communication protocol; each sub-module of each module of the DC power supply system is connected to one CAN bus; the centralized monitoring module realizes information interconnection with the wireless mobile terminal of the substation through GPRS, CDMA, radio frequency or WIFI wireless communication; micro-control The controller achieves information interconnection with external devices through the RS485 interface; the centralized monitoring module collects the status information of each module and the protection parameter information set by the industrial control touch screen through the CAN bus, and saves them in the memory, and the centralized monitoring module operates according to the load. and the set working current of the lithium iron phosphate battery, the intelligent control method is used to calculate the real-time controlled charger current, and the control command is sent to the charger module in the DC operating power supply, so as to realize the floating charge management of the lithium iron phosphate battery.

The utility model has the advantages of novel conception, reasonable structure, simple method and convenient implementation. The system of the utility model has excellent performance, high charge and discharge efficiency of the battery, small leakage current, large charge and discharge rate, strong load impact resistance of the power supply system, and wide operating temperature range. The system of the utility model has high reliability, and each module is connected to the DC bus through a relay switch, and is connected with several monitoring modules through the CAN bus; when a module fails, the module can be cut off in time without affecting The whole system works normally. Using the control method of the utility model can realize the online maintenance of the battery without manual intervention; it can also prevent the battery from working in a floating charge state for a long time, and effectively prolong the service life of the battery.

The beneficial effects of the utility model are: 1) Environmental protection: the ferric phosphate battery does not have the problem of environmental pollution in the production link, use link and scrap treatment link. 2) Saving resources: iron phosphate batteries are small in size and light in weight. Compared with lead-acid batteries, lithium iron phosphate batteries are only one-third of the volume of lead-acid batteries, and only weigh as much as lead-acid batteries. half.

Description of drawings

Fig. 1 is a structural schematic diagram of a DC power supply system for a substation of the present invention.

Fig. 2 is a schematic diagram of a redundant backup method for an energy storage module of a lithium iron phosphate battery of the present invention.

Fig. 3 is a schematic diagram of the lithium iron phosphate battery energy storage module of the present invention.

Fig. 4 is a structural diagram of the centralized monitoring module of the direct current power supply system for substations of the present invention.

Fig. 5 is a flow chart of the intelligent control method of the substation DC power supply system of the present invention.

Detailed ways

The utility model will be further described below in conjunction with the accompanying drawings through specific embodiments.

Referring to Fig. 1, in this embodiment, the whole system adopts the idea of centralized management and distributed control, and the DC operation power supply module, UPS power supply module, inverter power supply module, communication power supply module and lithium iron phosphate energy storage module are connected through the CAN bus On the centralized monitoring module. The lithium iron phosphate energy storage module is connected to the DC bus through the first relay switch KM1; each power module is connected to the DC bus through the second to fifth relay switches KM2~KM5, and each power module uses a lithium iron phosphate battery as backup battery.

Each module in the DC power system can realize system redundancy backup by increasing the number of modules connected in parallel to the DC bus, as shown in Figure 2, which is a schematic diagram of the redundant backup method for lithium iron phosphate energy storage modules.

Compared with the redundant backup of dual independent power systems used in traditional substation DC power systems, the technical feature of this power system structure is that each module is composed of multiple small-capacity sub-modules connected in parallel. Removing the sub-modules and putting in the backup sub-modules will not affect other normal functional modules, which improves the stability and reliability of the system. At the same time, these sub-modules will not fail at the same time, so the number of redundant backup sub-modules can be significantly reduced, thereby reducing the system cost.

In this embodiment, the centralized monitoring module adopts an embedded microcontroller, and the centralized monitoring module centrally collects data from each sub-power supply module and battery management system, and performs data fusion on the data of the entire system to judge the working status of the system. In abnormal working conditions, the faulty module can be removed from the DC bus by controlling the relay switches KM1~KM5 to ensure the safety of the entire system.

Referring to Fig. 3, in this embodiment, the lithium iron phosphate battery energy storage module is composed of a battery management system and a lithium iron phosphate battery pack connected in parallel. The battery management system consists of an LCD screen, a main control module, and an acquisition/balance module. The lithium iron phosphate battery management system is directly connected to the lithium iron phosphate battery pack. The acquisition module collects the voltage of the single battery and the voltage, current, and temperature of the battery pack. The main control module performs some predetermined algorithm processing on the collected data to determine the battery life. Working status, the working status of the battery is displayed in real time through the LCD screen on the battery management system, and transmitted to the centralized monitoring system through the CAN bus, and the centralized monitoring system then controls the charger.

Referring to Fig. 4, in this embodiment, the centralized monitoring module of the DC power system of the substation is composed of a microcontroller, a memory, an Ethernet communication interface of an intelligent substation, an industrial control touch screen, and multiple CAN, RS485 and GPRS or radio frequency wireless interfaces. The microcontroller collects the running status information of each power module, detection device and energy storage device through the CAN bus interface, collects the running status of the external connected devices of the system through the RS485 interface, and saves the status information in the memory. The microcontroller executes the system-level intelligent control algorithm, sends control instructions to each sub-module, and realizes the coordinated control between each power module and energy storage module. The memory is composed of storage media such as RAM, ROM, and Flash. The industrial control touch screen communicates with the microcontroller through the Ethernet or RS485 interface, and displays the system operating status information collected by the microcontroller, including the operating voltage, current, temperature, AC frequency, power, fault status, etc. of each module; at the same time The industrial control touch screen sets the parameters of the system operation through the man-machine interface, and saves them in the Flash medium of the memory. The microcontroller provides an Ethernet communication interface that meets the IEC61850 communication protocol to realize remote monitoring of smart substations. After the microcontroller receives instructions from remote monitoring, it analyzes the instruction information, and sends control instructions to the corresponding system modules to achieve target control. The communication interface composed of GPRS or radio frequency wireless unit sends the operation status information to the wireless mobile terminal in the substation.

Referring to Fig. 5, an embodiment of an intelligent control method for a DC power supply system of a substation is given. When the centralized monitoring module monitors the power supply failure of the power system, the power system works in the fault discharge stage, and the lithium iron phosphate battery pack serves as a backup battery to supply power to the power system. When the battery continues to discharge until the capacity is less than 10% or the battery voltage UBAT is less than the protection voltage Umin, the centralized monitoring module disconnects the relay switch KM1 to prevent over-discharge from damaging the lithium iron phosphate battery. If the backup battery is working in a normal state, the centralized monitoring module controls the relay switch and puts in a redundant lithium iron phosphate energy storage module to supply power to the power system.

If there is no power supply failure in the power supply system and it is detected that the battery meets the time requirement for automatic maintenance, the centralized monitoring module will automatically maintain and control the battery. The centralized monitoring module monitors whether the flag bit of automatic battery maintenance is 1, that is, it is in a discharge state. If the battery is in a discharge state, it monitors whether the battery voltage U _BAT is higher than the set maintenance discharge termination voltage U _O . The system load deeply discharges the battery. If the battery voltage is lower than the end-of-discharge voltage, the centralized monitoring module sets the automatic maintenance flag of the battery to 0. If the automatic maintenance flag of the monitoring battery is 0, the centralized monitoring module will charge the battery quickly and evenly until the capacity of the battery is greater than 98% or the battery voltage reaches the set upper limit value U _MAX , and then the automatic maintenance flag of the battery will be set 1. At the same time, clear the automatic maintenance timer T.

If the power supply of the power system is normal and there is no need for automatic maintenance of the battery, the centralized monitoring module will control the shallow charge and discharge of the battery to prevent the battery from working in a floating charge state for a long time, thereby improving the service life and performance of the battery. If it is detected that the battery capacity is greater than 90%, and the charging flag is 0, the centralized monitoring module controls and adjusts the output current of the charger through the monitored load current data, so that the battery is discharged at a small discharge rate until the battery capacity is less than 90%. After the discharge is over, the centralized monitoring module sets the charging mark position of the battery to 1, and at the same time controls the output current of the charger to charge the lithium iron phosphate battery at a high charging rate. , until the capacity of the battery is greater than 98%, at this time, the charging flag of the battery is set to 0.

Claims (4)

1. a transformer station uses DC power system, comprises direct current operative power source module, ups power module, inverter module, power supply module for communication, LiFePO4 energy-storage module and centralized monitor module, it is characterized in that:

Said LiFePO4 energy-storage module is connected on the dc bus through the first relay switch KM1; Said direct current operative power source module, ups power module, inverter module, power supply module for communication are connected on the dc bus through the second relay switch KM2, the 3rd relay switch KM3, the 4th relay switch KM4, the 5th relay switch KM5 respectively, and shared LiFePO4 energy-storage module; Said centralized monitor module realizes information communication through CAN communication bus and each module, and through DC bus powered; Every kind of module in the DC power system all can be parallel to the redundancy backup of the module number realization system of dc bus through increase;

Said LiFePO4 energy-storage module is to constitute by the ferric phosphate lithium cell group is parallelly connected with battery management system, the battery pack that the ferric phosphate lithium cell group is made up of a plurality of ferric phosphate lithium cells elder generations and back string.

2. transformer station according to claim 1 uses DC power system; It is characterized in that; Said DC power system adopts the common DC bus connected mode; Each module all can realize the plug and play of on-line operation, and system can excise the functional module that has fault automatically, and under the situation that does not influence the normal operation of system, malfunctioning module is carried out on-line replacing.

3. transformer station according to claim 1 uses DC power system; It is characterized in that said battery management system is made up of liquid crystal display screen, main control module and a plurality of collection/balance module, battery management system directly links to each other with the ferric phosphate lithium cell group; Acquisition module is gathered the voltage of cell and voltage, electric current and the temperature information of battery pack; Main control module carries out some predetermined algorithm with the data of gathering to be handled, and judges battery operated situation, and battery operated situation shows through the liquid crystal display screen on the battery management system in real time; And pass to centralized monitoring system through the CAN bus, centralized monitoring system is controlled the charger of direct current operative power source module again.

4. transformer station according to claim 1 uses DC power system; It is characterized in that; Said centralized monitor module; Be made up of microcontroller, memory, intelligent substation ethernet interface, industry control touch-screen and multichannel CAN bus, RS485 bus and wireless communication bus, microcontroller is realized interconnected through parallel bus, spi bus and I2C bus and memory; The industry control touch-screen is realized being connected with the communication of microcontroller through Ethernet or CAN EBI; Microcontroller realizes that through Ethernet interface and transformer substation remote monitoring system communication is connected, and meets the IEC61850 communication protocol; Each sub-module of every kind of module of DC power system is connected on one road CAN bus; The centralized monitor module realizes that through the mobile radio terminal of GPRS, CDMA, radio frequency or WIFI communication and transformer station information is interconnected; Microcontroller is realized with the information of external equipment interconnected through the RS485 interface; The centralized monitor module is collected the state information of each module and the protection parameter information that the industry control touch-screen is set through the CAN bus; And it is saved in the memory; The centralized monitor module is according to the ferric phosphate lithium cell operating current of load operation electric current and setting; The employing intelligence control method calculates the charger electric current of real-time control, and control command is sent to the charger module in the direct current operative power source, thereby realizes the float management of ferric phosphate lithium cell.

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