CN203326621U - Non floating charge lithium battery type DC (direct current) power system used for station - Google Patents

Abstract

A non-floating lithium battery type DC power supply system for stations, changing the long-term use of lead-acid batteries and online floating charging in traditional station DC power systems, adding a battery management system according to the characteristics of iron-lithium batteries, and separately setting up a working rectification module and charging The rectifier module uses a multi-stage step-down silicon chain to isolate the DC control bus and DC power bus, so that the iron-lithium battery pack does not need long-term online floating charging operation, which has outstanding substantive features. The utility model has the advantages of compact structure, easy operation, high safety performance, increased degree of automation, one-third reduction in the number of batteries, high cost performance of the system, and large-scale application can realize higher economic benefits and generate greater social benefits.

Description

Non-floating lithium battery type station DC power supply system

technical field

The utility model relates to a station DC power supply system in a substation, a converter station, a power plant and other electric power projects. Specifically, it uses The characteristics of the step-down silicon chain, the design of a new charging and discharging circuit and the corresponding control and protection device, so that the iron-lithium battery pack is in a non-floating charging lithium battery station DC power supply system that does not perform floating charging but is not offline. the

Background technique

Station DC power supply system is the working power supply for the protection, control and communication of power transmission and transformation equipment in substations, converter stations, power plants and other power projects. , Accident lighting and other accident electricity. For a long time, the DC power supply system for stations has adopted the online floating charge operation mode of the battery pack. Its main features are: ①It needs to supplement the capacity loss caused by the self-discharge of the battery pack; ②There is no battery management system, and it is maintained by regular balanced charging; ③ The battery pack is directly connected to the DC power bus through a circuit breaker (or fuse), and then the higher power bus voltage is adjusted to a voltage suitable for the load connected to the DC control bus through a step-down silicon chain device, so that it will continue uninterrupted after the AC is interrupted provide DC power. However, long-term floating charge operation ① will passivate the battery plate, resulting in battery capacity decline and life expectancy; The status is unknown; ③The battery pack is directly connected to the DC power bus, and it must be separated from the bus during the nuclear capacity discharge test. It must be replaced by a temporary battery pack or other measures to meet the requirements of the DL/T724-2000 battery pack not to be separated from the bus. . Therefore, when the above-mentioned situation is serious, when an accident occurs in the power grid, the battery pack cannot meet the power consumption during the accident, delaying the rescue of the accident, and even causing the accident to expand. the

Currently, iron-lithium battery station DC power supply systems are used in China, but based on the structure and operation mode of the original valve-regulated lead-acid battery, the lead-acid battery is simply replaced with iron-lithium battery, which does not comply with the charging and operating requirements of the iron-lithium battery. The discharge characteristics will also accelerate the capacity decline of the iron-lithium battery and reduce the operating life, which greatly reduces the cost performance. Therefore, it is difficult to apply the DC power system for the iron-lithium battery pack station directly in the floating charge mode in power engineering. the

Utility model content

The purpose of this utility model is to provide a non-floating charge lithium type station DC power supply realized by a step-down silicon chain device according to the characteristics that the iron-lithium battery is not suitable for floating charging operation, and the typical wiring structure of the current station DC power supply system The system is designed to avoid capacity decline and lifespan reduction caused by long-term floating charging of iron-lithium battery packs, and meet accident power consumption such as substation protection, control, and accident lighting. the

The purpose of this utility model is achieved in this way: a non-floating lithium battery type DC power supply system for stations, including a rectifier, a feed circuit, and an iron-lithium battery pack, wherein the feed circuit includes a DC control bus KM, and the rectifier The DC output terminal of the battery is connected to the DC control bus KM, and also includes a battery charging circuit, a DC power bus HM, a multi-stage step-down silicon chain device and a monitor; the battery charging circuit is composed of an AC air switch Q ₀ , a charging rectifier module M ₀ and DC air switch QF ₀ ; one end of the AC air switch _Q0 is connected to the AC incoming power supply, and the other end is connected to the input end of the charging rectifier module M ₀ ; one end of the DC air switch QF ₀ is connected to the charging rectifier module M ₀ The output end, the other end is connected to the DC power bus HM; the control end of the charging rectifier module M0 is connected to the monitor; the multi-level step-down silicon chain device is composed of multiple groups of silicon chains in series and each group of silicon chains is connected in parallel at both ends A bypass DC contactor is formed; the input end of the multi-stage step-down silicon chain device is connected to the DC power bus HM, the output end is connected to the DC control bus KM, and the control end is connected to the monitor;

The iron-lithium battery pack is connected to the DC power bus HM through the fuse R1.

The above non-floating lithium battery DC power supply system for station also includes an insulation detection device, the insulation detection device has a plurality of detection terminals and an output terminal, one of the detection terminals is connected to the DC power bus HM, and the output terminal is connected to the monitor . The feed circuit includes j DC output branches, j=1, 2,...n; the DC output branches are connected to the DC control bus KM through the DC air switch Q _j , and an insulation detection sensor is set on each DC output branch CT _j , each insulation detection sensor CT _j is connected to the detection end of the insulation detection device.

A shunt FL is also arranged between the iron-lithium battery pack and the DC power bus HM for detecting the size and direction of the iron-lithium battery pack, and the output end of the shunt FL is connected to the monitor. the

The rectification device is set up as follows: including k AC air switches Q _k , k working rectifier modules M _k , k=1, 2, 3...n and DC air switches QF ₃ ; one end of the AC air switches Q _k is connected to the AC inlet Line power supply, the other end is connected to the input end of the working rectification module M _k ; the output ends of all working rectification modules M _k are connected in parallel to one end of the DC air switch QF ₃ , and the other end of the DC air switch QF ₃ is the rectification device DC output.

The monitor includes a battery management system. The battery management system analyzes and manages the battery status in real time through the acquisition circuit and the equalization circuit, and dynamically maintains the battery through the monitor and the charging control and protection circuit. Charging control The battery management system starts or stops charging and rectifying module M ₀ for equalizing or supplementary charging of the battery pack according to the state of the iron-lithium battery pack. When the charging and rectifying module _M0 stops working, the battery is in a normal resting state due to the action of the multi-stage step-down silicon chain device.

The multi-stage step-down silicon chain device in the utility model is a five-stage step-down silicon chain device, which is composed of five groups of step-down silicon chains connected in series and a bypass DC contactor connected in parallel at both ends of each group of step-down silicon chains. The voltage drop of each silicon chain is 7V. When the contacts of the five bypass DC contactors are all opened, the voltage drop generated by the five-level step-down silicon chain device is 35V, that is, when the charging voltage of the DC power bus HM reaches 265V, the DC control bus connected with the DC load KM can also maintain a normal working voltage of 230V without causing overvoltage of the DC control bus KM; when the iron-lithium battery pack is required to supply power to the DC control bus KM, the monitor controls the The contacts of the five DC contactors are opened and closed to realize step-by-step voltage regulation to ensure that the voltage of the DC control bus KM is within a reasonable range. the

Among them, the iron-lithium battery pack is composed of iron-lithium batteries in series, and the iron-lithium battery is a lithium iron phosphate battery, model FP3291152; the model of the charging rectifier module M ₀ and the working rectifier module M _k is HD22020-3; the multi-stage step-down silicon chain The device is a five-level step-down silicon chain device, which is composed of five groups of silicon chains in series and a bypass DC contactor connected in parallel at both ends of each group of silicon chains. Each group of silicon chains steps down by 7 volts; the five-level step-down silicon chain device The model is DT-2B/300A/35V; the shunt model is 200A/75mV, 0.5 level; the monitor is based on the CAN bus monitoring system, the model is BMJ-FPC. The insulation detection device is an insulation detector, the model is JYM-2.

The actual working process of the utility model is as follows: when the AC power supply is normal, the working rectifier module M _k supplies power for the regular DC load on the DC control bus KM, and the power supply voltage is 230V. At this time, the monitor opens all the contacts of the five DC contactors of the five-stage step-down silicon chain device through the control board, and the voltage difference between the two ends of the five-stage step-down silicon chain must exceed 35V to conduct. If the battery pack is in a static state, its terminal voltage will not exceed 265V. Even if the iron-lithium battery pack is in the charging state, its voltage will not exceed 265V (when the number of batteries increases and the charging voltage needs to be increased, a seven-stage step-down silicon chain can be selected, and the voltage drop can reach 49V). Therefore, the five-stage step-down silicon chain is always in the cut-off state when the AC power supply is working normally, thereby preventing the working rectifier module M _k from floating charging the iron-lithium battery pack. After the AC interruption caused by an accident in the power grid, the working rectifier module M _k has no DC output. At this time, the iron-lithium battery pack continuously supplies power to the DC control bus KM and its DC load through the five-stage step-down silicon chain device. According to the actual terminal voltage of the iron-lithium battery pack, the monitor controls the contacts of the five DC contactors to open and close to realize step-by-step voltage regulation, so as to ensure that the voltage of the DC control bus KM is within a reasonable range. When the battery management system analyzes the iron-lithium battery pack needs to be charged according to the battery collection data, the monitor sends an instruction to start the charging and rectifying module _M0 to charge the iron-lithium battery pack. During the charging process, the equalization circuit of the battery management system charges each battery Perform balanced interventions.

The biggest difference between the non-floating lithium battery station DC power system and the traditional station DC power system is the addition of a battery management system and a dedicated charging rectifier module, and the use of multi-stage step-down silicon chains to isolate the DC power bus and DC control bus, so that Avoid long-term online floating charging operation for iron-lithium battery packs. However, iron-lithium batteries are not suitable for long-term online floating charging. Most iron-lithium battery manufacturers have clearly stated that their products cannot use long-term online floating charging. the

The beneficial effects of the utility model are: the DC power supply system for stations is widely used as power for accidents such as protection, control, communication, and accident lighting of power transmission and transformation equipment in power engineering, and as a working or backup power supply in the fields of electric power and communication. , its importance is self-evident. In the past, in order to ensure that the lead-acid battery maintains full capacity and the battery pack does not separate from the DC bus, combined with the large self-discharge and periodic equalization characteristics of the lead-acid battery, the power system has always used the wiring and operation mode of online floating charging, but the floating charging method will cause Long-term overcharging or undercharging of individual batteries shortens battery life. As a new battery, iron-lithium battery has very small self-discharge. Compared with lead-acid battery, it has better environmental protection, high capacity density and high current charge and discharge. It has been widely used in the field of electric vehicles, so it is very necessary to use it Introduced into substations, converter stations, power plants and other station-use DC power systems for power engineering, but the application of iron-lithium batteries in power systems must improve the traditional battery group wiring and management methods according to its technical characteristics such as small self-discharge. Only by changing the method of operation and maintenance can the technical advantages of iron-lithium batteries be maximized. the

The utility model changes the long-term use of lead-acid battery and online floating charging operation mode in the station DC power supply system, adds a battery management system according to the characteristics of the iron-lithium battery, sets up a working rectification module and a charging rectification module separately, and adopts multi-stage step-down silicon chain isolation The DC control bus and the DC power bus make the iron-lithium battery pack do not need long-term online floating charging operation, which has substantial characteristics and progress. Since the iron-lithium battery has many advantages such as wide operating temperature range, small self-discharge, long service life, high-rate discharge, etc., the utility model can satisfy the electricity demand for accidents in the power system to the greatest extent, and can reduce the use of lead-acid battery belts at the same time. to the problem of environmental pollution. the

The utility model has the advantages of compact structure, easy operation, high safety performance, increased degree of automation, one-third reduction in the number of batteries, high cost performance of the system, and large-scale application can realize higher economic benefits and generate greater social benefits. the

Description of drawings

Figure 1 is a block diagram of the system structure. the

Figure 2 is a system wiring diagram. the

Fig. 3 is a wiring circuit diagram of the step-down silicon chain device. the

Detailed ways

As shown in Figure 2, the DC power supply system for non-floating lithium battery type station is composed of the following parts, and the corresponding copper busbars, copper core cables, measurement and communication lines are used to connect the various devices and structural parts. the

Rectification device: Composed of high-frequency switch rectification module (M1~MN), 200A AC air switch (QF1, QF2), 315A DC air switch (QF3) and corresponding circuit connections. The air switches QF1 and QF2 are connected to the incoming power supplies from different substation AC power sources, and their output ends are respectively connected to the AC input ends of multiple parallel rectifier modules (M1~MN) through 25A AC air switches (1Q~NQ), and the rectifier modules ( The DC positive and negative output terminals of M1~MN) are respectively connected to the positive pole (+KM) and negative pole (-) of the DC control bus through the DC air switch (QF3). the

Feed circuit: It is composed of DC control busbar (KM) and each output branch. All regular DC loads are connected to them through 32A small or micro DC air switches (Q1~QN) in their respective circuits to realize power supply to regular DC loads. and branch protection. Q1~QN are configured according to the capacity and quantity of DC power supply loads. the

Iron-lithium battery pack (B): The iron-lithium battery pack (B) is connected to the DC power bus HM through the fuse R1. There is also a shunt FL between the iron-lithium battery pack and the DC power bus HM. The shunt FL The output is connected to a monitor. Among them, the fuse (R1) protects the iron-lithium battery pack (B), the DC air switch (QF0) and the charging rectifier module (M0) in the event of an external short circuit such as the DC power bus (HM). the

Multi-level step-down silicon chain device: use a five-stage step-down silicon chain device, including a step-down silicon chain group (D) and a control terminal (J). As shown in Figure 3, it is composed of five groups of silicon chains in series and a bypass DC contactor (K1~K5) connected in parallel at both ends of each group of silicon chains. Each group of silicon chains steps down 7V, and the five-level step-down silicon chain device The maximum voltage drop is 35V. the

Based on CAN bus monitoring system: including monitor (JKQ), battery management system (BMS), insulation tester (JYJC). The monitor (JKQ) is connected with the working rectifier module (M1~MN), charging rectifier module (M0), multi-stage step-down silicon chain device, battery management system (BMS) and insulation tester (JYJC) through the communication bus to carry out various Module control, monitoring, equalization, etc. The battery management system (BMS) is composed of battery acquisition circuit, battery equalization circuit, protection and control circuit, etc., and is connected to the iron-lithium battery pack (B). The monitor (JKQ) and the battery management system (BMS) control the working status of the multi-stage step-down silicon chain device, so that the iron-lithium battery pack (B) does not perform long-term online float charging except for forced equalization charging and supplementary charging, and at the same time The unidirectional conductivity and multi-level voltage adjustment of the step-down silicon chain (D) ensure that the battery pack (B) can continuously provide power with a suitable voltage for the DC control bus when the AC power supply is interrupted. The insulation detector (JYJC) collects the positive and negative pole voltages of the DC power bus (HM) respectively, and monitors the insulation of the bus through the insulation detection sensors (CT1~CTN) of each DC output branch and determines the branch with reduced insulation (line selection). the

The working method and usage method of the non-floating lithium battery station DC power system are as follows:

a) Group the components into cabinets, which are rectifier cabinets, feeder cabinets and battery cabinets. The unit cabinets are connected by cables, copper bars, measurement and communication lines and used together as a group screen.

b) When in use, the AC input terminal is connected to the AC380V power supply, and the 200A AC air switch (QF1 or QF2) is closed and sent to the high-frequency switch rectifier module (M1~MN), and the working rectifier module (M1~MN) outputs DC to 315A The DC air switch (QF3) inlet terminal and the DC air switch (QF3) output terminal are connected to the positive pole (+KM) and negative pole (-) of the DC control bus through cables, and are used for protection, control and communication (that is, regular DC load) to provide qualified DC operating power. During normal operation, the monitor (JKQ) and battery management system (BMS) collect DC voltage, current and battery status, and perform daily measurement, monitoring and maintenance management on the working rectifier module (M1~MN) and iron-lithium battery pack (B) . The insulation detector (JYJC) collects the DC voltage and the data of each branch (CT1~CTN) to monitor the insulation status of the system, and can send an alarm when the insulation drops and send it to the monitor (JKQ). After the iron-lithium battery pack (B) is fully charged, when the AC power supply of the five-stage step-down silicon chain device is normal, the control board of the five-stage step-down silicon chain device will open all contacts of the DC contactors (K1~K5), and the five-stage step-down silicon chain device will The step-down silicon chain device is in the cut-off state, and the iron-lithium battery pack (B) is in the non-floating hot standby state, ready to supply power to the load at any time. the

c) When one of the following conditions is met: ① After the iron-lithium battery pack (B) supplies power to the DC load (can be judged by the current direction of the shunt FL) or ② The battery management system (BMS) detects that the iron-lithium battery pack (B) reaches the replenishment When the charging condition is met, the monitor (JKQ) sends a charging work command to the charging and rectifying module (M0), and the charging and rectifying module (M0) completes the charging of the iron-lithium battery pack (B) according to the set charging parameters and procedures. the

The main functions and technical indicators of this system:

Main function: To provide a non-floating lithium battery DC power supply system for stations, aiming to use the step-down silicon chain device to realize the off-line floating charging operation mode, and avoid the capacity decline and lifespan reduction caused by long-term floating charging of the iron-lithium battery pack. The rectifier module of this system can be hot-swappable, with perfect AC and DC protection functions and intermittent charging mode. On the premise of meeting the power consumption needs of substation protection, control, accident lighting and other accidents, it prolongs the service life of the equipment and improves cost-effective equipment.

Technical indicators of DC power system for non-floating lithium battery station:

System capacity: 200Ah;

AC input voltage: 380V;

AC input current: 200A;

DC output current: 250A;

Charging voltage: 242V-252V;

Charging current: 20A-50A (0.1C ₁₀ -0.25C ₁₀ )

Voltage stability: 0.5%;

Ripple factor: 0.5%

Current stability: 1%;

Module current unbalance: 3%

Battery voltage inspection accuracy: 0.2%;

Number of insulation monitoring branches: 32 to 768;

Battery Quantity: 70pcs/group;

Monitoring management: BMS based on CAN bus;

Rated voltage of iron-lithium battery: 3.2V/cell;

Charging voltage of iron-lithium battery: 3.6V/cell (20°C);

End-of-discharge voltage of iron-lithium battery: 2.55V/cell;

Self-discharge capacity of iron-lithium battery: <3% after standing for 28 days (20°C);

Cycle life of iron-lithium battery: 1500 times.

Parameters of main devices and equipment:

Lithium iron phosphate battery: model FP3291152, Harbin Coslight Group;

High-frequency switching rectifier module: model HD22020-3, Emerson Power Company;

Monitor (built-in BMS): Model BMJ-FPC, Harbin Coslight Power Supply Company;

Insulation monitoring device: model JYM-2, Emerson Power Company;

AC air switch: model GM100M, Beijing People's Electrical Appliance Factory;

DC circuit breaker: model GM400 or GM100, Beijing People's Electrical Appliance Factory;

Step-down silicon chain: model DT-2B/300A/35V, Dalian Lushun Heli Power Supply Equipment Factory;

Shunt (FL): 200A/75mV, class 0.5.

Claims (7)

1. A non-floating lithium type station DC power supply system, comprising a rectifier, a feed circuit, and an iron-lithium battery pack, wherein the feed circuit includes a DC control bus KM, and the DC output of the rectifier is connected to the The DC control bus KM is characterized in that, Also includes battery charging circuit, DC power bus HM, multi-stage step-down silicon chain device and monitor; The battery charging circuit is composed of an AC air switch _Q0 , a charging rectifier module _M0 and a DC air switch _QF0 ; one end of the AC air switch _Q0 is connected to the AC incoming power supply, and the other end is connected to the input end of the charging rectifier module _M0 ; One end of the DC air switch QF ₀ is connected to the output end of the charging and rectifying module M ₀ , and the other end is connected to the DC power bus HM; the control end of the charging and rectifying module M 0 is connected to the monitor; The multi-level step-down silicon chain device is composed of multiple groups of silicon chains in series and a bypass DC contactor connected in parallel at both ends of each group of silicon chains; the input end of the multi-level step-down silicon chain device is connected to the DC power bus HM, and the output The terminal is connected to the DC control bus KM, and the control terminal is connected to the monitor; The iron-lithium battery pack is connected to the DC power bus HM through the fuse R1. 2. The non-floating lithium battery type station DC power supply system as claimed in claim 1, further comprising an insulation detection device, the insulation detection device has a plurality of detection terminals and an output terminal, wherein one detection terminal is connected to To the DC power bus HM, the output is connected to the monitor. 3. The non-floating lithium battery type station DC power supply system as claimed in claim 2, wherein the feed circuit also includes j DC output branches, j=1, 2, ... n; the The DC output branch is connected to the DC control bus KM through the DC air switch Q _j , and an insulation detection sensor CT _j is arranged on each DC output branch, and each insulation detection sensor CT _j is connected to the detection terminal of the insulation detection device. 4. The non-floating lithium battery type station DC power supply system as claimed in claim 1, wherein a shunt FL is also arranged between the iron-lithium battery pack and the DC power bus HM, and the output of the shunt FL terminal connected to the monitor. 5. As claimed in claim 1 or 2 or 3 or 4, the non-floating lithium battery type station DC power supply system is characterized in that the rectification device includes k AC air switches Q _k and k working rectification modules M _k , k=1, 2, 3...n and the DC air switch QF ₃ ; one end of the AC air switch Q _k is connected to the AC incoming power supply, and the other end is connected to the input end of the working rectification module M _k ; all working rectification modules M The output end of _k is connected in parallel to one end of the DC air switch QF ₃ , and the other end of the DC air switch QF ₃ is the DC output end of the rectification device. 6. The non-floating lithium battery type station DC power supply system as claimed in claim 5, characterized in that, The iron-lithium battery pack is composed of iron-lithium batteries in series, and the iron-lithium battery is a lithium iron phosphate battery, model FP3291152; The models of the charging rectification module _M0 and the working rectification module _Mk are HD22020-3; The multi-level step-down silicon chain device is a five-stage step-down silicon chain device, which is composed of five groups of silicon chains in series and a bypass DC contactor connected in parallel at both ends of each group of silicon chains, and each group of silicon chains steps down by 7 volts ; The model of the five-stage step-down silicon chain device is DT-2B/300A/35V; The shunt model is 200A/75mV, class 0.5; The monitor is a monitoring system based on the CAN bus, and the model is BMJ-FPC. 7. The non-floating lithium battery type DC power supply system for stations according to claim 2 or 3, wherein the insulation detection device is an insulation tester, the model of which is JYM-2.

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