CN203119616U - Distributed direct-current power supply subsystem of intelligent substation - Google Patents

Abstract

The utility model discloses a distributed direct current power supply subsystem of an intelligent substation, which comprises a power supply monitoring device, which is respectively connected with a system state monitoring device and a power supply system through a field bus, and the power supply system is also connected with a battery pack, and the battery pack adopts Lithium iron phosphate battery pack or valve-regulated lead-acid battery pack. The DC power monitoring device is also connected with the DC insulation monitoring device through the field bus. The DC power monitoring device is also connected to the battery monitoring system and the battery maintenance system through the field bus, and the battery monitoring system and the battery maintenance system are connected to the battery pack. According to the layout planning of the substation and the design capacity of the electrical equipment, the DC power supply is divided into several small systems that operate independently and can be arranged close to the electrical equipment. Each DC power subsystem is small in scale, simple in structure, safe and reliable, and can Better guarantee the stability and safety of the DC power supply in this area.

Description

Intelligent Substation Distributed DC Power Supply Subsystem

technical field

The utility model relates to a distributed DC power supply subsystem of an intelligent substation.

Background technique

At present, smart substations require secondary equipment to be distributed in layers and installed locally. When the main transformer side protection measurement and control, low-voltage side protection measurement and control, merging unit and other equipment are far away from the DC power supply screen, the DC power supply needs to add a power distribution screen and use a large number of cables to supply power to the equipment. At present, the station DC power supply has become a very large-scale system, and there are hundreds of feeders to cover the DC power consumption equipment of the whole station. If a conventional DC power supply system is adopted, the DC power supply circuit must be too long. This will add to the introduction of things like

1. It is difficult for the circuit breaker to cooperate with the step difference after the bus has been divided into sections for many times.

2. Increased grounding hazards. There are many possible faults such as DC bus entering AC, DC bus crossing, positive and negative bus being grounded at the same time and multi-point grounding, and large distributed capacitance can easily lead to malfunction of protection equipment. This is also a common failure point of the station DC power supply system with a voltage level of 220kV and above.

Of course, the conventional DC power supply system still exists:

3. It is difficult to make a correct evaluation of the performance of the battery when the battery is in the floating charge standby state for a long time.

4. The system design is complex and has many faults. After the DC bus loses power, the whole station equipment is paralyzed.

5. A section of busbar only depends on a set of storage batteries, and the design reliability is not high.

6. After the DC failure, if the main components such as the battery, charging module, monitoring device, etc. fail, the staff needs to disconnect the battery, and it is difficult to repair the DC power system in time and quickly.

Chinese patent (application number: 2011101300550, patent name: Distributed DC power supply uninterruptible power supply system), which discloses a distributed DC power supply uninterruptible power supply system, including a DC bus and several DC power supply subsystems distributed in various occasions , the several DC power supply subsystems are all connected to the DC bus to form a power supply network, each DC power supply subsystem includes: AC input unit, energy supply unit, energy storage device and multiple DC output circuits, and energy storage Units include lead-acid and lithium batteries. However, the patent does not involve the modular design of the battery, nor does it mention how to detect whether the DC bus is mixed with the AC, it does not involve the collection of battery cell temperature and internal resistance, and it does not solve how to maintain the entire life of the battery pack. The performance of the storage battery pack does not involve converting the electric energy supplied by photovoltaic power generation equipment and wind power generation equipment into a stable DC power supply for stations, so as to realize energy saving and consumption reduction of green energy.

Utility model content

The purpose of this utility model is to solve the above problems and provide an intelligent substation distributed DC power supply subsystem, which divides the DC power supply into several small systems that operate independently according to the layout planning of the substation and the design capacity of the electrical equipment. And it can be arranged close to the electrical equipment. Each distributed DC power supply subsystem is small in scale, simple in structure, safe and reliable, and can better ensure the stability and safety advantages of the DC power supply in this area.

In order to achieve the above object, the utility model adopts the following technical solutions:

An intelligent substation distributed DC power supply subsystem, including a power monitoring device, the power monitoring device is respectively connected to the system status monitoring device and the power supply system through the field bus, and the power supply system is also connected with a modular design and supports plug-and-play Ready-to-use battery pack connection, each module of the battery pack contains several batteries.

Further, the power monitoring device is also connected to the DC insulation monitoring device through a field bus.

Further, the power monitoring device is also connected to a battery monitoring system through a field bus, and the battery monitoring system is connected to a battery pack.

Further, the power monitoring device is also connected to the storage battery maintenance system through the field bus, and the storage battery maintenance system is connected to the storage battery pack.

The system state monitoring device includes an analog quantity acquisition module, a switch quantity acquisition module or a fault detection module.

The system status monitoring device is a conventional configuration unit of the DC system, and is connected with the power monitoring device through a field bus such as RS485.

The analog quantity acquisition module is used for sampling analog quantities such as voltage and current on the AC incoming line and the DC bus.

The switching value acquisition module is used for sampling the switching state and tripping state of the DC feeder.

The fault detection module is used for detection of lightning arrester faults, fuses on the output side, and tripping of lightning protection circuit breakers.

The DC insulation monitoring device includes a bus insulation detection module, a branch insulation detection module or an AC mixing detection module.

The DC insulation monitoring device is used to monitor faults such as direct current bus entering AC, direct current bus crossing, and positive and negative bus being grounded at the same time. Using the leakage current method to detect the ground insulation status of the feeder will not inject low-frequency AC signals into the busbar to ensure the robustness and stability of the busbar. The single-bus design does not have DC bus cross-channeling faults, and the fault detection related to the above-mentioned anti-error can be realized through a dedicated circuit.

The busbar insulation detection module is used to detect the insulation resistance of the DC module to the ground.

The branch insulation detection module is used to detect the insulation resistance of the DC feeder to the ground.

The AC mixing detection module is used to detect whether the DC bus is mixed with AC.

The battery monitoring system includes a battery voltage detection module, a battery pack temperature detection module or a battery pack internal resistance detection module.

The battery monitoring system and the battery maintenance system work together. The battery monitoring system is used to monitor the voltage, temperature, internal resistance and other data of the single batteries in the system.

The battery voltage detection module is used to collect battery cell voltage.

The battery pack temperature detection module is used to collect the temperature of the battery cells.

The internal resistance detection module of the battery pack is used to collect the internal resistance of the battery cells.

The storage battery maintenance system includes a positive and negative pulse charging device, a passive charging balancing device or an active charging balancing device.

The battery maintenance system is used to balance the batteries according to the information monitored by the battery monitoring system, improve the performance consistency of a single battery inside the battery pack, improve the life and capacity of the entire battery pack, and ensure the performance of the lithium battery pack.

For lead-acid batteries, the use of positive and negative pulse charging devices can increase the charging speed, and at the same time play the role of battery activation and balance. Passive charge equalization devices and active charge equalization devices are available for lead-acid and lithium-ion battery packs. The passive charging equalization device consumes the electric energy of the high-voltage single battery side parallel resistance scheme during the equalization charging process, so as to realize the uniform voltage and capacity of the single battery in the whole group. The active charge equalization device achieves the same voltage capacity between adjacent cells through the two-way DC-DC energy conversion method of adjacent cells, so as to finally achieve the consistency of each cell in the entire group.

The power supply system includes a power switching control device, a high-frequency switching charging device, a photovoltaic charging device or a wind power charging device.

The power supply system is used to provide a stable and reliable DC power supply for the station.

The power supply switching control device is used for online switch-on and withdrawal control switching between the main battery pack and the standby battery pack, so as to ensure the safety of the system power supply.

The high-frequency switching charging device is used for fast charging of the main and backup battery packs. The high-frequency switching charging device is composed of multiple AC-DC charging modules. The main battery pack refers to the battery pack currently connected to the DC bus, and the backup battery pack refers to the battery pack that has been separated from the DC bus.

The photovoltaic charging device is used to convert the electric energy supplied by the photovoltaic power generation equipment into stable DC electric energy for the station.

The wind power charging device is used to convert the electric energy supplied by the wind power generation equipment into a stable DC power supply for the station.

Several distributed DC power supply subsystems communicate with the main control room through the station control layer network, and the distributed DC power supply subsystems, the station control layer network and the main control room together form a distributed DC power supply system.

The power monitoring device is the core control unit of the system. It adopts high-performance embedded platform design. It can realize the collection and forwarding of operation and fault information, the logic control of the entire power system, the charging and maintenance of the main and backup battery packs, and ultimately ensure the stability of the DC power supply.

The power monitoring device is connected to the station control layer network of the smart substation through the Ethernet port, and follows the design model and communication interface of the standard "DLT 329-2010 Communication Interface for Substation Low-Voltage Power Supply Equipment Based on DLT860" to realize two-way information interaction and meet the needs of smart substations based on DL /T 860 communication consistency requirements. The time synchronization function based on IEEE1588 meets the timing synchronization needs of the distributed network of measurement and control applications, and can solve the bottleneck of long delay time and poor synchronization ability of Ethernet.

The storage battery pack is the core component of the DC power supply for the station, and it adopts a lithium iron phosphate battery pack or a valve-regulated lead-acid battery pack. The battery pack adopts a modular design and supports plug-and-play. Each module of the battery pack contains several batteries. When the battery pack fails, it only needs to be replaced with a spare battery pack of the same specification to quickly restore the distributed DC power supply. subsystem. The battery pack can be divided into a main battery pack and a backup battery pack. The so-called main battery pack refers to the battery pack currently connected to the DC bus, and the backup battery pack refers to the battery pack that has been separated from the DC bus.

The storage battery pack is used to store electric energy, and guarantee the DC power supply when the AC power is lost.

Beneficial effects of the utility model: the original large-scale DC power supply system is divided into several distributed DC power supply subsystems according to the space interval. This design method has the following advantages:

1. Distributed DC power supply subsystems and power loads are arranged in a centralized manner, each subsystem is small in scale, the number of protective equipment such as circuit breakers is reduced, and the level difference coordination of circuit breakers is easier to realize.

2. The design of single busbar without silicon chain is adopted, the structure is simple, and there are few fault points such as grounding and AC mixing. At the same time, the number of feeder lines is small and the distributed capacitance is small, which can effectively reduce the hazard of single-point grounding and improve the reliability of the entire system. It can also avoid failures such as equipment misoperation and false alarms caused by sampling signal attenuation caused by too long cables and sampling accuracy deviations in conventional DC systems. The grounding monitoring of AC feeders using the leakage current method, the introduction of detection methods such as AC mixing and DC cross-channeling, can more comprehensively monitor the power consumption status of the entire power system, and more accurately reflect the ground insulation status of the system.

3. Lithium batteries have a high equalization charging frequency, and its battery performance parameters are easier to obtain. By monitoring the internal resistance and temperature of a single battery, it can reflect its health status in real time and realize SOC estimation. The adoption of the battery equalization system can improve the performance consistency of a single battery inside the battery pack, and improve the life and capacity of the whole pack.

4. Distributed power supply, if there is a problem with the power supply of a single subsystem, it is limited to the paralysis of this section, and the fault area is small, which will not cause the paralysis of the DC power system of the whole station. To a certain extent, it will improve the safety factor and reliability of the whole station operation . The system is small in scale and can be installed in a small space near the field equipment. Moreover, the distributed DC power supply subsystem is consistent with the current mainstream smart substation layered and distributed design concepts, and can be placed in the same outdoor cabinet together with power-consuming equipment such as merging units and smart terminals.

5. The lithium iron phosphate battery pack replaces the conventional valve-regulated lead-acid battery pack. It has the advantages of long life, safety and non-explosion, wide operating temperature range, large capacity, green environmental protection, fast charging, and no memory utility. Conditions for large-scale promotion and application. Main backup battery configuration, higher reliability of power supply. Because lithium batteries are suitable for full and full discharge management, the performance and health of the battery are reflected to the operating personnel in real time, and hidden dangers of the battery can be discovered earlier.

6. Modular design of main components, adopting unified interface and unified specification. It can improve the production efficiency of screen assembly, and the design is more flexible. The battery module, charger module, monitoring device and other parts adopt a plug-and-play design. If the above-mentioned components fail on site, they can be hot-swapped and replaced with spare parts. Improved failure recovery efficiency.

in addition:

7. The monitoring device adopts the communication model and communication interface that meet the recommended electric power standards, so that the interface of the entire system and the upper-level equipment is more standard and consistent.

8. Support the access of photovoltaic, wind power and other green new energy sources, and support energy saving and consumption reduction.

Description of drawings

Figure 1 is a functional block diagram of the distributed power supply subsystem;

Figure 2 is a distributed DC power system;

Figure 3 is a schematic diagram of the wiring of a conventional distributed DC power supply subsystem using lead-acid batteries;

Figure 4 is a schematic diagram of the 1+1 mode wiring of the distributed DC power supply subsystem;

Figure 5 is a schematic diagram of the 2+1 mode wiring of the distributed DC power supply subsystem;

Figure 6 is a schematic diagram of the 2+2 mode wiring of the distributed DC power supply subsystem;

Figure 7 is a block diagram of new energy access;

Figure 8 is a schematic diagram of the wiring of a 1+1 mode lithium battery pack;

Fig. 9 is the equivalent circuit of the AC mixing detection selected by the utility model.

Among them, 1. Power supply monitoring device, 2. System status monitoring device, 3. DC insulation monitoring device, 4. Battery monitoring system, 5. Battery maintenance system, 6. Power supply system, 7. Battery pack, 8. Field bus, 9 , main control room, 10, station control layer network, 11, distributed DC power supply subsystem, 21, analog quantity acquisition module, 22, switch quantity acquisition module, 23, fault detection module, 31, bus insulation detection module, 32, Branch circuit insulation detection module, 33. AC mixed detection module, 41. Battery voltage detection module, 42. Battery pack temperature detection module, 43. Battery pack internal resistance detection module, 51. Positive and negative pulse charging device, 52. Passive charging equalization Device, 53. Active charging equalization device, 61. Power switching control device, 62. High-frequency switching charging device, 63. Photovoltaic charging device, 64. Wind power charging device.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

As shown in Figure 1, an intelligent substation distributed DC power supply subsystem includes a power monitoring device 1, the power monitoring device 1 is connected to the system status monitoring device 2 and the power supply system 6 through a field bus 8, the power supply System 6 is also connected to battery pack 7 .

Further, the power monitoring device 1 is also connected to the DC insulation monitoring device 3 through the field bus 8 .

Further, the power monitoring device 1 is also connected to the battery monitoring system 4 through the field bus 8 , and the battery monitoring system 4 is connected to the battery pack 7 .

Further, the power monitoring device 1 is also connected to the battery maintenance system 5 through the field bus 8 , and the battery maintenance system 5 is connected to the battery pack 7 .

The system state monitoring device 2 includes an analog quantity acquisition module 21 , a switch quantity acquisition module 22 or a fault detection module 23 .

The DC insulation monitoring device 3 includes a bus insulation detection module 31 , a branch insulation detection module 32 or an AC mixing detection module 33 .

The battery monitoring system 4 includes a battery voltage detection module 41 , a battery pack temperature detection module 42 or a battery pack internal resistance detection module 43 .

The storage battery maintenance system 5 includes a positive and negative pulse charging device 51 , a passive charging balancing device 52 or an active charging balancing device 53 .

The power supply system 6 includes a power switching control device 61 , a high frequency switching charging device 62 , a photovoltaic charging device 63 or a wind power charging device 64 .

The storage battery pack 7 is the core component of the DC power supply for the station, and the lithium iron phosphate battery pack 7 or the valve-regulated lead-acid battery pack 7 is used. The battery pack 7 adopts a modular design and supports plug-and-play. When the battery pack 7 fails, it only needs to be replaced with a spare battery pack of the same specification, and the distributed DC power supply subsystem 11 can be quickly restored.

As shown in Figure 2, some of the distributed DC power supply subsystems 11 communicate with the main control room 9 through the station control layer network 10, and some of the distributed DC power supply subsystems 11, the station control layer network 10 and the main control room 9 The three together form a distributed DC power system.

The power monitoring device 1 is the core control unit of the system. It adopts high-performance embedded platform design. It can realize the collection and forwarding of operation and fault information, the logic control of the entire power supply system, the charging and maintenance of the main and backup battery packs 7, and ultimately ensure the stability of the DC power supply.

The power monitoring device 1 is connected to the station control layer network 10 of the intelligent substation through an Ethernet port, and follows the design model and communication interface of the standard "DLT 329-2010 Communication Interface for Substation Low-Voltage Power Supply Equipment Based on DLT 860" to realize two-way information interaction and meet the needs of intelligent The substation is based on the communication consistency requirements of DL/T 860. The time synchronization function based on IEEE1588 meets the timing synchronization needs of the distributed network of measurement and control applications, and can solve the bottleneck of long delay time and poor synchronization ability of Ethernet.

As shown in Figure 3, if the battery pack 7 still uses a valve-regulated lead-acid battery pack 7, the design of this subsystem is similar to that of a station-use conventional DC power supply system with a small load. The battery packs are all connected to the DC bus, and the charging device is also connected to the DC bus.

As shown in Figure 4, the charging device, the monitoring device and the two battery packs are all connected to the DC bus, the charging device is respectively connected to the two battery packs, and the monitoring device will also monitor the charging device, the first battery pack and the second battery pack The information exchange incoming line enters the charging device.

As shown in Fig. 5, considering the reliability of the power supply system, a group of storage batteries 7 can be added on the basis of the 1+1 mode to increase the redundancy of the system, which is called the 2+1 mode in the present invention. During normal operation, two sets of batteries are hung on the busbar for power supply at the same time, and the third set of batteries is used as a replacement battery. The charging device preferentially charges the battery that is separated first.

As shown in Figure 6, for some sections of 500kV and above intelligent substations, there is a double-bus design, and the 2+2 mode can be adopted (generally, two sets of batteries are used to supply power to the two sections of the bus, and two sets of backup battery sets 7 are used as two back-up power for the segment bus) configuration. Of course, two sets of 1+1 mode configuration distributed DC power supply subsystem schemes can also be used to supply power to the two busbars respectively. The battery pack 7 adopts a modular design and supports plug-and-play. When the battery pack 7 fails, it only needs to be replaced with a spare battery pack of the same specification, and the distributed DC power supply subsystem 11 can be quickly restored.

As shown in FIG. 7 , the power supply system 6 is a core component in the distributed DC power supply subsystem 11 . It consists of a wind power charging device 64 , a photovoltaic charging device 63 , a high-frequency switching charging device 62 , a power switching control device 61 and other parts. The access of green and environment-friendly power sources such as wind power charging device 64 and photovoltaic charging device 63 realizes the diversification of electric energy input and makes the system more robust.

Taking the 1+1 mode configuration lithium-ion battery pack system as an example, the wiring diagram is shown in Figure 8 below:

The high-frequency switch charging module is composed of multiple AC-DC charging modules. As shown in the figure, the charging module and the control unit work in coordination to complete the charging maintenance of the two lithium battery packs and the bus power supply function. The control unit controls the charging of two sets of lithium battery packs. When the 1# lithium battery pack is powered by the 2# lithium battery pack, K1 and K4 are closed and K2 and K3 are disconnected; when the 2# lithium battery pack is fully charged, K4 is disconnected. , the 2# lithium battery pack is in the hot standby state; when the 1# lithium battery pack is low in power, the 2# lithium battery pack is powered and the 1# lithium battery pack is charged. At this time, K2 and K3 are closed, and K1 is disconnected; when 1 # When the lithium battery pack is fully charged, K2 is disconnected, and the 1# lithium battery pack is in hot standby state. The cycle continues over and over again.

The wiring of the 2+2 mode 7 configuration lithium-ion battery pack system is slightly different from that of the 1+1 mode: 1# lithium battery pack is powered by one mother, 2# lithium battery pack is used as the second mother power supply, and 3# lithium battery pack is used as one mother The backup power supply, 4# lithium battery is used as the backup power supply of the second mother. The high-frequency switch charging module and the power switch control coordinate work to complete the charging maintenance of the two lithium battery packs and the corresponding bus power supply function. The unilateral switching method is similar to the above-mentioned 1+1 configuration.

As shown in Figure 9, the AC mixed-in detection equivalent circuit selected in this system, DC insulation monitoring has become a very important part of the entire DC power system. Especially after several design errors by design institutes at all levels, the DC insulation inspection needs to detect faults such as the DC bus entering the AC, the DC bus crossing, and the positive and negative bus being grounded at the same time. We use the leakage current method to detect the insulation status of the feeder to the ground, and will not inject low-frequency AC signals into the busbar to ensure that the busbar is robust and stable. The single-bus design does not have DC bus cross-channeling faults, and the fault detection related to the above-mentioned anti-error can be realized through a dedicated circuit. R1 and R2 are the balance bridge resistors, and C1 is the equivalent capacitance of the DC system.

Although the specific implementation of the utility model has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the utility model. Those skilled in the art should understand that on the basis of the technical solution of the utility model, those skilled in the art do not need to Various modifications or deformations that can be made with creative efforts are still within the protection scope of the present utility model.

Claims (10)

1. transforming plant distributed DC power supply subsystem of intellectuality, it is characterized in that, comprise electrical power monitoring device, described electrical power monitoring device is connected with electric power system with the system state monitoring device respectively by fieldbus, described electric power system also is connected with the batteries that adopts modularized design and support plug and play, comprises several storage batterys in every pack module of described batteries.

2. the transforming plant distributed DC power supply subsystem of a kind of intellectuality as claimed in claim 1 is characterized in that, described electrical power monitoring device also is connected with the D.C. isolation monitoring device by fieldbus.

3. the transforming plant distributed DC power supply subsystem of a kind of intellectuality as claimed in claim 1 is characterized in that, described electrical power monitoring device also is connected with the accumulator monitoring system by fieldbus, and described accumulator monitoring system is connected with batteries.

4. the transforming plant distributed DC power supply subsystem of a kind of intellectuality as claimed in claim 1 is characterized in that, described electrical power monitoring device also is connected with the battery service system by fieldbus, and described battery service system is connected with batteries.

5. the transforming plant distributed DC power supply subsystem of a kind of intellectuality as claimed in claim 1 is characterized in that, described system state monitoring device comprises analogue collection module, switch acquisition module or fault detection module.

6. the transforming plant distributed DC power supply subsystem of a kind of intellectuality as claimed in claim 2 is characterized in that, described D.C. isolation monitoring device comprises that bus insulation detection module, branch road insulation monitoring module or interchange sneak into detection module.

7. the transforming plant distributed DC power supply subsystem of a kind of intellectuality as claimed in claim 3 is characterized in that, described accumulator monitoring system comprises battery tension detection module, batteries temperature detecting module or batteries internal resistance detection module.

8. the transforming plant distributed DC power supply subsystem of a kind of intellectuality as claimed in claim 4 is characterized in that, described battery service system comprises positive negative pulse stuffing charging device, passive charging equalization apparatus or active charge balancer.

9. the transforming plant distributed DC power supply subsystem of a kind of intellectuality as claimed in claim 1 is characterized in that, described electric power system also comprises power supply switching control, HF switch charging device, photovoltaic charged device or wind-powered electricity generation charging device.

10. the transforming plant distributed DC power supply subsystem of a kind of intellectuality as claimed in claim 1 is characterized in that, described batteries adopts lithium iron phosphate storage battery group or analysing valve control type lead-acid accumulator battery group.

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