CN211930271U - An intelligent energy storage device for distribution transformer capacity increase - Google Patents

Abstract

The utility model discloses an intelligent energy storage device for power distribution and capacity expansion, comprising an optical storage unit, external auxiliary equipment, a central monitoring unit and a power conversion unit; the optical storage unit includes an energy storage battery, a battery management system and a photovoltaic array; the external auxiliary equipment includes a distribution and transformation platform load information acquisition module connected to the central monitoring unit, which is used to collect the platform load information and send it to the central monitoring unit; the battery management system is connected to the central monitoring unit, using The SOC of the energy storage battery is collected and sent to the central monitoring unit; the photovoltaic array and the energy storage battery are respectively connected to the DC side of the power conversion unit through the DC contactor; both the DC contactor and the power conversion unit are controlled by the central monitoring unit unit; the AC side of the power conversion unit is connected to the grid. The utility model can improve the power supply capability and power supply quality of the distribution network.

Description

An intelligent energy storage device for distribution transformer capacity increase

technical field

The utility model relates to the field of electric power control, in particular to an intelligent energy storage device used for distribution transformer capacity expansion.

Background technique

With my country's economic development and social progress, the power consumption of industrial and agricultural production and people's livelihood is also increasing year by year, and the demand for electricity is diversified, and the power supply requirements for the power sector are getting higher and higher. In many rural grid areas covered by the State Grid Corporation, the guarantee of power supply is still a prominent problem due to the weak local grid structure. In particular, the load rate of electricity consumption is low throughout the year, the peak electricity consumption is seasonal or seasonal, and the peak load in a specific period is prominent, which often causes distribution transformers in the station area, line overload and low voltage in the station area, and the power supply capacity cannot be guaranteed.

How to solve the heavy overload operation of distribution transformers, avoid equipment accidents, and improve power supply quality, power supply reliability and high-quality service level is particularly important.

Utility model content

In view of the problems existing in the above technologies, the utility model provides an intelligent energy storage device used for increasing the capacity of a distribution transformer, which can improve the power supply capability and power supply quality of the distribution network.

The technical scheme adopted by the utility model to solve its technical problems is:

An intelligent energy storage device for power distribution and capacity expansion, comprising an optical storage unit, external auxiliary equipment, a central monitoring unit and a power conversion unit;

The optical storage unit includes an energy storage battery, a battery module management unit and a photovoltaic array;

The external auxiliary equipment includes a distribution and transformation platform load information acquisition module connected to the central monitoring unit, which is used to collect the platform load information and send it to the central monitoring unit;

The battery management system is connected to the central monitoring unit for collecting the SOC of the energy storage battery and sending it to the central monitoring unit;

The photovoltaic array and the energy storage battery are respectively connected to the DC side (DC bus) of the power conversion unit through a DC contactor; both the DC contactor and the power conversion unit are controlled by a central monitoring unit; Carry out on-off control, start and stop and work mode control of the power conversion unit;

The AC side of the power conversion unit is connected to the grid.

Preferably, RS485 communication is adopted between the central monitoring unit and the optical storage unit, the power conversion unit and the external auxiliary equipment, and the communication protocol is MODBUS.

Preferably, the optical storage unit (photovoltaic array and energy storage battery) is connected to the power conversion unit by means of a DC cable with crimp terminals.

Preferably, the power conversion unit includes a DC/DC converter and a DC/AC converter.

Preferably, the AC side of the power conversion unit is connected to the power grid through external auxiliary equipment. The power conversion unit is connected with the external auxiliary equipment through a three-phase four-wire AC cable.

Preferably, the external auxiliary equipment includes an HPLC (power line broadband carrier) module, and the distribution and transformation station load information acquisition module in the external auxiliary equipment is connected to the station concentrator through the HPLC module (HPLC communication technology), and the station area is collected in real time. Load information, including the load rate of the station area, etc.

Preferably, the central monitoring unit includes a controller, a communication module, a switch, and a display, the controller adopts an embedded microprocessor to perform data processing, control logic, etc., and the communication module includes an RS485 communication interface and an Ethernet port, The switch includes a high-speed 4G module, a WIFI networking service, an Ethernet port, and the like.

Preferably, the central monitoring unit communicates with the distribution network master station (remote monitoring) through a high-speed 4G module.

Preferably, the energy storage battery is a battery cluster composed of several battery modules, and each battery module includes a plurality of battery cells; the battery management system adopts a two-level structure of a battery module management unit and a battery control unit; each The battery module is equipped with a battery module management unit, which is responsible for the management of battery cells in the battery module, including information collection, balance, information upload and thermal management of each battery cell; the entire battery cluster is equipped with a battery control unit, which is connected with each battery module. The management unit is connected in communication and is responsible for managing each battery module management unit, and is also responsible for current collection, total voltage collection, insulation resistance detection and SOC estimation of the battery cluster, and makes it out of operation when the state of the battery cluster is abnormal.

Preferably, the central monitoring unit acquires the status of the optical storage unit and the power conversion unit through communication for display and abnormal alarm.

Preferably, the battery management system of the optical storage unit includes a voltage monitoring module and a temperature monitoring module;

The voltage monitoring module collects the voltage of the energy storage battery based on the voltage sensor, and judges whether the voltage of the energy storage battery is higher than the preset voltage upper limit value or lower than the preset voltage lower limit value through the comparator, and if so, then Output the corresponding overvoltage and undervoltage alarm signals to the central monitoring unit (one input end of the comparator is connected to a voltage sensor to collect the voltage signal of the energy storage battery, the other input end is connected to the upper/lower voltage limit value, and the output end is connected to the central monitoring unit. monitoring unit);

The temperature monitoring module collects the temperature of the energy storage battery based on the temperature sensor, and judges whether the temperature of the energy storage battery is higher than the preset temperature upper limit value or lower than the preset temperature lower limit value through the comparator, and if so, then Output the corresponding over-temperature or under-temperature alarm signal to the central monitoring unit (one input end of the comparator is connected to the temperature sensor to collect the temperature signal of the energy storage battery, the other input end is connected to the upper/lower temperature limit value, and the output end is connected to the central monitoring unit);

When the central monitoring unit receives an overvoltage, undervoltage, overtemperature or undertemperature alarm signal from the battery management system, it controls the power conversion unit to reduce power, stand by or shut down according to the severity level.

Preferably, the intelligent energy storage device adopts a pole-mounted installation method, and is connected to the 380V main line of the power distribution station area in a parallel manner.

Preferably, the external auxiliary equipment is connected to the power grid through a grid-connected cable.

Preferably, the external auxiliary equipment includes a grid-connected circuit breaker (exit circuit breaker) and a grid-connected cable (grid access cable); one side of the grid-connected circuit breaker is connected to the AC side of the power conversion unit, and the other side is connected to the AC side of the power conversion unit. The side is connected to the grid-connected cable, and the grid-connected cable is connected to the 380V main line of the distribution line distribution station area through the parallel groove clamp.

Preferably, the grid-connected circuit breaker is configured with an overcurrent protection module and a leakage protection module.

The external auxiliary equipment includes a switching power supply, which is used for taking power from the AC side of the power conversion unit to supply power to the central monitoring unit, the battery management system, the power conversion unit controller and the power modules in the external auxiliary equipment.

The intelligent energy storage device for distribution and capacity expansion further includes a box body, and the central monitoring unit, the optical storage unit, the power conversion unit, and the external auxiliary equipment are all arranged in the box body;

The box is provided with a smoke detector, a temperature and humidity sensor and an air conditioner, which are used to monitor and adjust the internal environment of the smart energy storage device box;

A door magnetic switch is arranged inside the box to detect whether the box door is forcibly opened.

Beneficial effects:

The intelligent energy storage device for distribution transformer capacity expansion provided by the utility model includes a central monitoring unit, an optical storage unit, a power transformation unit and external auxiliary equipment, and is connected to the 380V main line of the distribution station area in a parallel manner. Or during the peak load power consumption period during the Spring Festival, by connecting the intelligent energy storage device to cut peaks and fill valleys, the dynamic capacity increase of the distribution transformer in the station area can be realized, which can effectively improve the overload of the distribution transformer, the overload of the line, and the low voltage in the station area, and reduce the line loss in the station area. , improve the operating economy and improve the reliability of the power supply of the distribution network. The intelligent energy storage device can also be used for temporary power supply, emergency power protection, and uninterrupted operation during the off-load power consumption peak period, so as to improve the power supply capacity and service level of the distribution network.

The intelligent energy storage device itself can be used as both a power source and a load. According to the user's electricity demand and electricity consumption characteristics at different time periods, the intelligent energy storage device is charged during the trough period of electricity consumption, and discharged during the day according to the real-time demand of the user's load, thereby increasing the power supply capacity on the spot. The intelligent energy storage device can alleviate the seasonal distribution overload, line overload and low voltage problems of the distribution network, and at the same time meet the power requirements of the distribution network without power outage, emergency power protection, temporary power supply, etc. , low noise, energy saving and emission reduction, green environmental protection" characteristics.

Description of drawings

FIG. 1 is a schematic structural diagram of an intelligent energy storage device in an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present utility model more clearly understood, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as there is no conflict with each other.

As shown in FIG. 1 , in view of the problems of distribution network overload, high-voltage line overload, and user low voltage, the present invention provides an embodiment of an intelligent energy storage device for distribution and capacity expansion.

This embodiment provides an intelligent energy storage device for power distribution and capacity expansion, including a central monitoring unit, an optical storage unit, a power conversion unit, and external auxiliary equipment. The intelligent energy storage device is connected in parallel to the 380V main line in the distribution station area to dynamically increase the capacity of the distribution transformer in the station area. The device adopts the pole type installation method, which can be connected to the power grid without power failure. Through the HPLC module, the load information of the station area is collected in real time by means of power carrier communication, and the operation of the optical storage unit is controlled. The power conversion unit can perform phase-split control to suppress the unbalance of the three-phase load. In addition, during the peak period of off-load power consumption, the device can also be used for temporary power supply, emergency power protection, and power-off operations.

According to the survey data, at present, there are peak periods of concentrated electricity consumption in rural power grid stations during summer and winter, continuous overload is concentrated in the afternoon and evening, and 60% of the distribution transformers are overloaded for 4-6 hours. The comprehensive overload rate and overload duration , for the seasonal long-term (4-6 hours) overload of the mainstream 50kVA distribution transformer in the rural grid, considering a certain margin, configure the intelligent energy storage device with a power/capacity of 15kW/60kWh.

The central monitoring unit adopts AM335X microprocessor based on ARM Cortex-A8 core, including RS485 communication interface, Ethernet port, high-speed 4G module, WIFI networking service, etc. Including real-time data acquisition, data processing, control operation, alarm management, time synchronization, screen monitoring, energy management and communication with remote monitoring systems and other functions. Downward monitoring and energy management, security monitoring, operation monitoring and operation control, configure system operation strategy, and complete online maintenance of system software. Upwards, the energy storage system information is uploaded through the high-speed 4G module, and can be controlled from a distance. Device debugging can be realized through WIFI networking service and Ethernet port. The central monitoring unit performs an abnormal alarm on the status of the battery and the power converter on the spot, starts and stops the power converter and controls the power, and realizes the control logic of automatic power compensation and suppression of three-phase load imbalance. The working mode of the power conversion unit can be controlled. When the load rate of the station area is greater than the high fixed value and the SOC of the energy storage battery is greater than the dischargeable fixed value, the discharge of the energy storage battery is controlled. When the load rate of the station area is less than the low fixed value and the SOC of the energy storage battery is less than It can charge a fixed value, control the charging of the energy storage battery, and set a certain hysteresis interval to prevent frequent startup. When the control is in the off-grid mode, it outputs a constant voltage at a given voltage. The central monitoring unit has a reliable protection strategy. Battery status for safe charging and discharging and protection.

The energy storage battery in the optical storage unit is composed of several battery modules connected in series, forming a battery cluster as a whole. In this embodiment, each battery module is composed of 16 battery cells in series and 2 in parallel, and the single cell adopts a 3.2V lithium iron phosphate battery; The total output voltage of the energy storage battery is in the range of 200-400V, and the combination of constant current charging and constant voltage charging is adopted. The photovoltaic modules use polysilicon solar panels with a rated power of 250W and an operating voltage of 36V. The battery management system monitors the voltage and temperature of the battery cells, and realizes battery status monitoring, operation control, insulation monitoring, balance management, SOC estimation, protection alarm, data storage and communication functions. The battery management system adopts a two-level architecture of BMU (Battery Module Management Unit) and BCU (Battery Control Unit). BMU is responsible for battery cell and battery module management, and integrates functions such as information collection, balance, information upload, and thermal management of each battery cell. one. The BCU is responsible for managing all BMUs in a battery cluster, and has functions such as current collection, total voltage collection, insulation resistance detection, and SOC estimation of the battery cluster. The cluster is out of operation to ensure battery safety.

The power conversion unit automatically follows the grid synchronization to realize DC/DC and AC/DC conversion. The DC side input range meets 30-800V DC, and the output is 380AC 50Hz. It charges and discharges the energy storage battery to meet the grid-connected power factor and power quality requirements. With grid-connected and off-grid working modes, with active power regulation, reactive power regulation, three-phase unbalance and harmonic suppression capabilities, with over/under voltage protection, over/under frequency protection, phase sequence or polarity error protection, DC input Overload protection, output short-circuit protection, anti-islanding protection, over-temperature protection, lightning protection, insulation detection and other functions, with external communication interface.

The intelligent energy storage device includes a box body, and the central monitoring unit, the optical storage unit, the power conversion unit and the external auxiliary equipment are all arranged in the box body.

The external auxiliary equipment includes a grid-connected circuit breaker, a grid-connected cable, etc., which can realize the distribution network access of the intelligent energy storage device. The grid-connected circuit breaker is equipped with overcurrent protection and leakage protection to achieve fault isolation; the grid-connected cable (access cable) is connected to the distribution line through the parallel trench clip to exchange energy with the distribution network.

The external auxiliary equipment includes an HPLC module, which is used to realize the collection of load information (including load current) of the intelligent energy storage device.

The external auxiliary equipment also includes a smoke detector, a temperature and humidity sensor and an air conditioner, which are used to monitor and adjust the internal environment of the intelligent energy storage device box.

The external auxiliary equipment also includes a door magnetic switch, which cooperates with the access control system of the cabinet door for system protection, and sends a signal to the central monitoring unit to give an alarm when it is detected that the cabinet door is forcibly opened.

The external auxiliary equipment also includes a switching power supply, which is used as an auxiliary power supply (power backup) device, and takes power from the AC side of the power conversion unit for the central monitoring unit, the battery management system, the power conversion unit controller, and other power modules in the external auxiliary equipment. powered by.

The working principle of the intelligent energy storage device used for distribution and capacity expansion in this embodiment is as follows:

The central monitoring unit collects the load information of the station area in real time through the external auxiliary equipment (the HPLC module uses the power carrier communication mode), including the station area load rate, three-phase voltage, three-phase current, active power, reactive power, etc.;

When the load rate of the station area is greater than the high fixed value and the SOC of the energy storage battery is greater than the dischargeable fixed value, the central monitoring unit controls the energy storage battery to supply power to the grid through the power conversion unit (the energy storage battery discharges);

When the load rate of the station area is less than the low fixed value and the SOC of the energy storage battery is less than the chargeable fixed value, the central monitoring unit controls the power grid to charge the energy storage battery through the power conversion unit;

When the energy storage battery is fully charged and the load rate of the station area is less than the high fixed value, the central monitoring unit controls the photovoltaic array to supply power to the grid through the power conversion unit.

And a certain hysteresis interval can be set to prevent frequent initiation of charge and discharge control.

Further, the load information of the station area includes active power and reactive power; if the power factor calculated according to the active power and the reactive power is less than 1, after the active power demand of the power grid is preferentially met, the energy storage battery is controlled to perform reactive power on the power grid. compensate.

Further, the platform load information includes three-phase voltage;

During the off-grid peak period of power consumption, the intelligent energy storage device is controlled to work in off-grid mode, which is used for temporary power supply, emergency power protection, and power outage operations; when the intelligent energy storage device is controlled to work in the off-grid mode, the central monitoring unit Send a three-phase voltage control command to the power conversion unit (that is, constant voltage control, so that the power conversion unit outputs a constant voltage at a given voltage);

When the intelligent energy storage device is controlled to work in the grid-connected mode, the central monitoring unit sends three-phase current control commands (ie constant current control) to the power conversion unit according to the real-time collected load information of the station area;

The three-phase unbalanced control is suppressed by performing the phase-separated control.

Further, when the load power P _L is greater than r ₁ (eg 0.95) times the transformer capacity P _T , and the energy _storage battery SOC is greater than p ₁ (eg 8%), according to P = min{ _PL -r ₁ · _PT , P _{maximum dischargeable} } Calculate the active power P _discharge that can be discharged by the energy storage battery, calculate the three-phase current that can be compensated for the power grid according to the P _discharge and the current load three-phase voltage, and issue the corresponding control command to the power conversion unit, Among them, P _{L -r 1} ·PT is the active power to be compensated, and P _{can be discharged} as the maximum discharge power of the energy storage battery; and control the DC contactor between the energy storage battery and the DC bus to close, and the connection between the photovoltaic array and the DC bus The DC contactor between them is disconnected, and the energy storage battery is controlled to supply power to the grid through the power conversion unit;

When it is detected that the load power P _L is less than r ₂ (eg 0.7) times the transformer capacity P _T , and the battery SOC is less than p ₂ (eg 100%), according to P _{charge =} min{r ₁ ·PT _-PL , the _{maximum P can be Charge} } Calculate the active power P _charge that can be charged by the energy storage battery, calculate the three-phase current that can be charged for the energy storage battery according to the P _charge and the three-phase voltage of the current load in the station area, and issue the corresponding control command to the power conversion unit. P _{can be charged} as the maximum charging power of the energy storage battery; and the DC contactor between the energy storage battery and the DC bus is controlled to close, the DC contactor between the photovoltaic array and the DC bus is disconnected, and the power grid is controlled to pass the power conversion unit to the storage battery. able to charge the battery;

When the energy storage battery is fully charged and the load rate of the platform area is less than r ₁ times P _T , the DC contactor between the control energy storage battery and the DC bus is disconnected, the DC contactor between the photovoltaic array and the DC bus is closed, and the control The photovoltaic array supplies power to the grid through the power conversion unit.

The central monitoring unit can adopt a three-level protection mechanism for the current protection, voltage protection and temperature protection of the battery. Control the power conversion unit according to the alarm information uploaded by the central monitoring unit. When a first-level alarm occurs, the central monitoring unit informs the power conversion unit to reduce power; when a second-level alarm occurs, the central monitoring unit notifies the power conversion unit to stand by (stop sending PWM commands, stop charging or discharging); when a third-level alarm occurs, The central monitoring unit informs the power conversion unit to stop (power conversion unit controller power off, forced shutdown, power conversion unit stops working), after a delay, the central monitoring unit actively disconnects the DC link between the energy storage battery and the photovoltaic array and the DC bus contactor. When the alarm disappears, execute the recovery process until the system resumes normal operation.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and replacements made within the spirit and principles of the present invention Improvements, etc., should be included within the protection scope of the present invention.

Claims (10)

1. an intelligent energy storage device for distribution and capacity expansion, characterized in that it comprises an optical storage unit, external auxiliary equipment, a central monitoring unit and a power conversion unit; The optical storage unit includes an energy storage battery, a battery management system and a photovoltaic array; The external auxiliary equipment includes a distribution and transformation platform load information acquisition module connected to the central monitoring unit, which is used to collect the platform load information and send it to the central monitoring unit; The battery management system is connected to the central monitoring unit for collecting the SOC of the energy storage battery and sending it to the central monitoring unit; The photovoltaic array and the energy storage battery are respectively connected to the DC side of the power conversion unit through a DC contactor; both the DC contactor and the power conversion unit are controlled by a central monitoring unit; The AC side of the power conversion unit is connected to the grid. 2 . The intelligent energy storage device for power distribution and capacity expansion according to claim 1 , wherein the photovoltaic array and the energy storage battery are both connected to the power conversion unit by means of a DC cable with crimp terminals. 3 . 3. The intelligent energy storage device for distribution transformer capacity expansion according to claim 1, wherein the external auxiliary equipment comprises an HPLC module, and the distribution transformer platform area load information acquisition module in the external auxiliary equipment passes through the HPLC module Connect with the station concentrator to collect the load information of the station area in real time. 4 . The intelligent energy storage device for distribution and variable capacity expansion according to claim 1 , wherein the central monitoring unit is communicatively connected to the main station of the distribution network. 5 . 5 . The intelligent energy storage device for power distribution and capacity expansion according to claim 1 , wherein the energy storage battery is a battery cluster composed of several battery modules, and each battery module includes a plurality of battery cells. 6 . The battery management system adopts a two-level structure of a battery module management unit and a battery control unit; each battery module is configured with a battery module management unit; the entire battery cluster is configured with a battery control unit, and the battery control unit and each battery module manage Unit communication connection. 6. The intelligent energy storage device for power distribution and capacity expansion according to claim 1, wherein the battery management system comprises a voltage monitoring module and a temperature monitoring module; The voltage monitoring module collects the voltage of the energy storage battery based on the voltage sensor, and judges whether the voltage of the energy storage battery is higher than the preset voltage upper limit value or lower than the preset voltage lower limit value through the comparator, and if so, then Output corresponding overvoltage and undervoltage alarm signals to the central monitoring unit; The temperature monitoring module collects the temperature of the energy storage battery based on the temperature sensor, and judges whether the temperature of the energy storage battery is higher than the preset temperature upper limit value or lower than the preset temperature lower limit value through the comparator, and if so, then Output the corresponding over-temperature or under-temperature alarm signal to the central monitoring unit. 7. The intelligent energy storage device for distribution, variable capacity and capacity expansion according to claim 1, wherein the external auxiliary equipment comprises a grid-connected circuit breaker and a grid-connected cable; one side of the grid-connected circuit breaker is connected to a grid-connected circuit breaker. The AC side of the power conversion unit is connected, and the other side is connected to the grid-connected cable. The grid-connected cable is connected to the 380V main line of the power distribution station area through the parallel trench clip. 8 . The intelligent energy storage device for power distribution and capacity expansion according to claim 7 , wherein the grid-connected circuit breaker is configured with an overcurrent protection module and a leakage protection module. 9 . 9 . The intelligent energy storage device for power distribution and capacity expansion according to claim 1 , wherein the external auxiliary equipment comprises a switching power supply, which is used for taking electricity from the AC side of the power conversion unit as the central monitoring unit, 10. 10 . The battery management system, the power conversion unit controller and the external auxiliary equipment are powered by the power modules. 10. The intelligent energy storage device for distribution and capacity expansion according to any one of claims 1 to 9, characterized in that it comprises a box body, the central monitoring unit, the optical storage unit, the power conversion unit and the external Auxiliary equipment is set in the box; The box is provided with a smoke detector, a temperature and humidity sensor and an air conditioner, which are used to monitor and adjust the internal environment of the smart energy storage device box; A door magnetic switch is arranged inside the box to detect whether the box door is forcibly opened.

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