KR20180127106A - Energy Storage apparatus for AC High Speed Railway - Google Patents

Abstract

The present invention relates to an energy storage apparatus for an AC-based high speed railway substation. The objective of the present invention is to build an energy storage apparatus system suitable for AC-based high speed railway substation in contrast to a peak power reduction apparatus for DC which has been widely used up to now. To this end, the energy storage apparatus for an AC-based high speed railway substation applies a multi-level inverter to a power conversion apparatus to operate in conjunction with a high voltage single phase AC voltage, and performs a demand power calculation to quickly identify and apply a load pattern of a concentrated control type of controller for controlling a power conversion apparatus and a high speed railway substation so as to secure efficient power operation, system stability, and reliability in consideration of a consumption pattern and am operation plan of the high speed railway substation.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy storage apparatus for an AC-

The present invention relates to an energy storage device for an AC-based high-speed railway substation, and more particularly, to an energy storage device for an AC-based high-speed railway substation which stores energy through regenerative energy and substation power generated during braking of a high speed train, To an energy storage device for an AC-based high-speed railway substation capable of achieving efficient demand power supply.

As is well known, generally, the electric power demand in the railway sector has a load pattern capable of reducing large peak power with a small energy storage capacity because of a large difference between an average load and a peak load, The system is very effective against the investment.

In addition, the energy storage system can contribute to the improvement of utilization ratio of regenerative energy and the stabilization of the line voltage generated in the process of repeatedly starting and braking the vehicle.

These energy storage devices are being actively applied to urban railways using 1,500V DC power. The DC transmission system of the city railway has already been applied to the railway advanced countries and the domestic market because of the short distance between the substations of 3 ~ 3.5km and frequent train start and stop characteristics.

FIG. 1 is a diagram showing the configuration of a direct current energy storage device applied to an urban railway substation. Referring to FIG. 1, a forward rectifier 4 for converting AC power to DC power and an energy storage device 10).

Phase AC power is supplied from the substation 20 and converted to a DC power of 1,500 Vdc through the rectifier 4 to save power for reducing the peak to the energy storage device 10 or to use the regenerative energy of the train 2 To charge the battery.

At the start of the train 2, the peak power reduction function is performed by receiving an instantaneous increase in the amount of power from the energy storage device 10.

On the other hand, high-speed railway such as KTX (Korea Train eXpress), which has been operating since 2004, has a larger capacity than an urban railway and the distance between substations is relatively far. Therefore, a high-voltage single- For example, 55 kV), it is necessary to configure the power supply system.

In addition, in order to maintain the constant rate of the high-speed train in a situation where the high-speed rail usage is rapidly increasing every year, more trains can be operated in the substation feeding section than the planned train. In this case, The power is greatly increased.

Therefore, the importance of developing an AC energy storage device for supplying peak power of a high-speed railway substation is increasing. To this end, it is necessary to overcome the economic disadvantages such as low utilization of regenerative energy compared with direct current and additional facilities, and it should be accompanied by energy storage system operation considering the load pattern of high-speed railway.

* Prior Art Documents: 'Study on Energy Saving Effect by Application of Energy Storage System', Journal of the Korean Society for Railway, 12 (9), 2009.

The present invention has been made in view of the circumstances of the prior art described above, and unlike conventional peak power reduction devices for direct current, it is aimed to construct an energy storage system suitable for an AC-based high-speed railway substation, It is a concentrated control type controller for applying a multilevel inverter to a power conversion device to operate in conjunction with single-phase AC voltage and controlling a power conversion device, and performs demand power calculation to quickly identify and apply a load pattern of a high-speed railway substation And to provide an energy storage device for an AC-based high-speed railway substation capable of efficiently operating the power plant considering the consumption pattern and the operation plan of the high-speed railway substation, and securing system stability and reliability.

In order to achieve the above object, according to a preferred embodiment of the present invention, power is supplied from a high-speed railway substation 20 to charge a battery 32, and electric power charged in the battery 32 is supplied to a high- (30) for an AC-based high-speed railway substation, the AC-based high-speed railway substation being provided with a battery (32) and a transformer (34) A conversion device (36); A demand power calculation unit 40 for calculating a demand forecast, setting an operation strategy set value for the energy storage device, managing a reference power value for charging / discharging determination, and calculating and predicting a power demand through the reference power value; And a controller (42) for comparing the output of the battery (32) and the output of the demand power calculator (40) to control the power converter (36) to perform power charging and discharging Energy storage for high-speed railway substations is provided.

Preferably, the power inverter 36 is connected in series and comprises a plurality of multilevel cell inverters 38 of IGBTs. An energy storage device for an AC-based high speed railway substation is provided.

Preferably, the power inverter 36 comprises a plurality of cell inverters connected in parallel to divide the rated capacity of the device by 1 / N.

Preferably, the demand power calculation unit 40 calculates a daily demand power demand based on a load pattern of a substation and a schedule of train operation, predicts a demand, and the load pattern is a load pattern for the same past date target. And the first and second reference powers serving as a reference for charging and discharging are calculated based on the load pattern and the demand calculation. The energy storage device for an AC-based high-speed railway substation is provided.

Preferably, the controller 42 determines whether the current time is a dischargeable time zone or a rechargeable time zone when the battery charge amount and the load amount signal are received every hour, and if the current time is a rechargeable time zone, If the current time zone is a dischargeable time, the second reference power is compared with the current load amount. If the current charging time is shorter than the second reference power, Wherein the controller is configured to selectively control the operation of the high-speed railway substation, the operation standby, and the protection operation.

The energy storage device for an AC-based high-speed railway substation according to the present invention charges a battery in a time zone or a nighttime in which power consumption is low and discharges it in a peak power time zone using the energy to enable optimized power consumption. It is possible to expect reduction of electric power charges for high-speed railway operation through optimal operation for charging and discharging.

1 is a diagram showing a DC storage device for DC power applied to a conventional urban railway substation,
FIG. 2 is a block diagram showing the configuration of an energy storage device for an AC-based high-speed railway substation according to an embodiment of the present invention;
3 is a diagram illustrating a configuration of a power conversion apparatus included in an energy storage device for an AC-based high-speed railway substation according to an embodiment of the present invention.
4 is a block diagram showing the configuration of a control unit for controlling an energy storage device for an AC-based high-speed railway substation according to an embodiment of the present invention.
FIG. 5 is a flowchart illustrating a signal flow of an energy storage device for an AC-based high-speed railway substation according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram illustrating a configuration of an energy storage device for an AC-based high-speed railway substation according to an embodiment of the present invention. FIG. 3 is a block diagram of an energy storage device for an AC- FIG. 4 is a block diagram showing a configuration of a control unit for controlling an energy storage device for an AC-based high-speed railway substation according to an embodiment of the present invention.

The energy storage device 30 for an AC-based high-speed railway substation according to an embodiment of the present invention differs from the energy storage device 30 for a DC peak power reduction device, which has been widely used until now, This is a power conversion device to operate in conjunction with a single-phase AC voltage of high voltage for a multi-level inverter, a centralized control system for controlling the power conversion device, a fast grasp of the load pattern of the high speed railway substation, It is a device that enables efficient power operation considering the consumption pattern and operation plan of high-speed railway substation, system stability and reliability by performing demand power calculation to be applicable.

The energy storage device 30 for an AC-based high-speed railway substation according to an embodiment of the present invention is configured to charge the battery 32 by receiving power from the high-speed railway substation 20, Voltage high-speed railway substation, which provides electric power to a high-speed railway electric railway vehicle 2. The electric energy storage device 30 includes an on / And a power conversion device 36 for generating an AC voltage through an off-switching operation.

In addition, the energy storage device 30 for an AC-based high-speed railway substation according to an embodiment of the present invention may include a demand forecasting unit, an operation strategy setting value setting unit for managing an energy storage unit, A demand power calculation unit 40 for calculating and predicting the power demand through the power demand calculation unit 40; And a controller 42 for comparing the output of the battery 32 and the output of the demand power calculator 40 to control the power inverter 36 to perform power charging and discharging.

The energy storage device 30 for an AC-based high-speed railway substation according to an embodiment of the present invention includes a single phase coplanar transformer 34, a power conversion device 36, a battery 32, a control unit 42, a demand power calculation unit 40, Phase voltage of 55 kV through a high-speed railway substation and share the peak power through the associated energy storage device. The power conversion device 36 converts the battery, which is a direct current power source, into AC, and is interlocked with a controller 42 for driving the battery. The control unit 42 controls the operation of the energy storage device 30 by receiving the battery signal and the operation command from the output of the operation strategy unit and controls the power conversion unit 36 and the battery 32 to be operated stably do.

That is, the energy storage device 30 for an AC-based high-speed railway substation according to an embodiment of the present invention supplies electric power supplied from the substation 20 to a high-speed railway electric railway vehicle 2 through a wire electrically connected to the electric railway train 2 do. The energy storage device 30 for an AC-based high-speed railway substation according to an embodiment of the present invention receives electric power from the high-speed railway substation 20 and stores it or transmits the regenerative energy generated when the electric motor 2 is braked to the battery 32 Energy is stored, and the stored electric power shares the peak electric power generated at the time of simultaneous activation of the plurality of electric trains 2, thereby enabling efficient power consumption.

FIG. 5 is a flowchart illustrating a signal flow of an energy storage device for an AC-based high-speed railway substation according to an embodiment of the present invention.

Referring to FIG. 1, the power inverter 36 is composed of a plurality of multilevel cell inverters 38 connected in series and composed of IGBTs.

In addition, the power inverter 36 is configured by connecting a plurality of cell inverters in parallel so that the rated capacity of the device can be divided by 1 / N.

That is, the power inverter 36 applies a multi-level inverter to connect with a high-voltage 55 kV AC voltage, which is composed of a plurality of modules in the form of a cell inverter. Each cell inverter applies an IGBT, which is a power semiconductor element, to perform an on / off operation to generate an AC voltage. When N cell inverters are applied, each cell inverter shares 1 / N of the rated capacity of the system, and a harmonic reduction effect can be expected due to the multi-level inverter.

On the other hand, the demand power calculation unit 40 calculates a daily demand power demand based on a load pattern of a substation and a daily train power demand, predicts a demand, and the load pattern is a load pattern for the same past date target, The first and second reference powers that are the reference of charge and discharge are calculated by the pattern and demand calculation.

The demand power calculation unit 40 sequentially determines the operation of the energy storage device with the function of predicting the demand, establishing the ESS operation strategy, and determining charge / discharge operation. In the substation demand forecasting function, the load pattern of the substation under the control of the system and the schedule of the train operation are inputted, and the power demand of each unit is predicted. Here, the load pattern is statistically acquired for the same date on the past data, and the demand forecast data is obtained by reflecting the train schedule of the corresponding substation.

Based on the obtained demanded power prediction data, the reference power 1, 2 for determining the charging / discharging pattern of the energy storage device and the charging / discharging operation for one day is determined. Actions up to the establishment of the ESS operation strategy are carried out until the first train on that date begins.

When the actual train starts to operate, the battery charge status (SOC: Stage of Charge) and load are measured, and the charging / discharging operation of the energy storage device is performed by comparing with the constraint conditions (reference power 1/2, charge amount upper / . The determined operation command is transmitted to the controller 42 of the power conversion apparatus, and efficient energy management is performed in accordance with the load characteristics of the high-speed railway substation.

In summary, the demand power calculation unit 40 performs optimal operation of the energy storage device for the high-speed railway through the function of predicting the demand of the substation, establishing the operation strategy of the daily energy storage device, and determining the charging / discharging operation of the energy storage device. Demand forecasts for substation demand forecast the power demand pattern of high - speed railway substations and the daytime demand power of the high - speed railway in the substation.

This requires a database to store the power consumption patterns of the high-speed railway substations by time zone, and a database to store the schedule of the high-speed railway in the substation power supply section where the energy storage devices are installed. Based on this database, it is possible to automatically predict the power demand after deriving the correlation between power consumption pattern and schedule information of high - speed railway.

In the stage of establishing the energy storage device operation strategy, the time of charging and the time of discharging are determined according to the amount of power demanded for the day during the day predicted in the previous step.

The reference power 1 is a load reference value used for determining the charging operation. If the load is less than the reference value, the battery is charged. The reference power 2 is a reference value used for determining the discharging operation. Peak power supply. The reference power 1 or 2 is determined in the operation strategy establishing step together with the battery charge / discharge pattern setting through the demand power calculator 40, and the control unit 42 ) Algorithm is constituted. This makes it possible to efficiently manage the energy stored in the battery.

In the battery charge / discharge operation determination step, determination is made in real time, and a charge / discharge operation, a protection operation, and a standby state are performed based on the charge / discharge pattern established in the previous step, reference power 1, The power converter command is determined.

The battery charge amount and the load amount signal are applied every hour, and it is confirmed whether the current time is the dischargeable time zone or the rechargeable time zone. In the case of a rechargeable time zone, the current load is compared with the reference power 1, and if the load is large, the operation is waiting for the operation. If the load is small, the battery is charged. On the other hand, if the current time zone is a dischargeable time, the discharge operation, the standby for operation, and the protection operation are selectively determined by comparing the reference power 2 with the current load and considering the battery charge amount.

To this end, the control unit 42 determines whether the current time is a dischargeable time zone or a chargeable time zone when the battery charge amount and the load amount signal are received every hour, and if the current time is a rechargeable time zone, If the current time zone is a dischargeable time, the second reference power is compared with the current load amount. If the current charging time is shorter than the second reference power, An operation standby, and a protection operation.

On the other hand, the control unit 42 is configured to operate independently for the interface CPU 46 and the master CPU responsible for the sequence and control, in order to improve the processing burden of the master CPU 44. The interface CPU 46 is responsible for data transmission and reception with an energy management system (EMS), a battery management system (BMS), and the like, which are peripheral devices, and the master CPU 44 performs sequence control, Protection functions, system monitoring, power control, and PWM signal generation. Therefore, the power conversion device 36 including the control unit 42 monitors the battery status in real time through communication with the BMS, communicates with the EMS, and performs control by receiving the state information of the wire and the valid / invalid power command.

FIG. 6 shows the amount of power of a high-speed railway substation to which an energy storage device is applied as a result graph according to an embodiment of the present invention. The red bar graph represents the load, and the blue bar graph represents the power received from the KEPCO system.

When the energy storage device of the present invention is applied, it can be confirmed that the amount of power supplied from the electric power system according to the maximum receiving power level (reference power 2) set by the algorithm is limited. The charging operation of the energy storage device is performed when the electric charge is lower than a reference power of 1 for an inexpensive night time zone and is performed until the battery is fully charged.

Figure 7 shows the output and charge state of an energy storage device during a day according to one embodiment of the present invention. As a result obtained under the same conditions as the graph of FIG. 6, it can be seen that the charge amount (SOC) increases from 40% to 100% by supplying power from the electric power system during the nighttime charging operation and charging the battery. On the other hand, in the discharge operation period determined by the reference power 2, it can be seen that the energy storage device performs power supply to the high-speed railway substation for peak power sharing.

As described above, the energy storage device for a high-speed railway substation according to an embodiment of the present invention is different from the DC-based energy storage device that has been applied in urban railway so far, and has characteristics such as a long transition period and a large power consumption of a high- Based energy storage system suitable for a high-speed railway system having an AC power source. The system configuration consists of a power conversion device and controller using a multi-level inverter suitable for the 55-kV line voltage, and an operational strategy for optimizing the urban railroad load characteristics and power consumption. The operation pattern of the energy storage device is determined based on the cumulative power consumption data of the high-speed railway substation and the data of the vehicle driving schedule of the substation section. By thus determining the operation pattern of the energy storage device, the battery is charged in a low- Thereby enabling optimized power consumption. In addition, this system and optimal operation can be expected to reduce electric power charges for high-speed railway operation.

Meanwhile, the energy storage device for an AC-based high-speed railway substation according to an embodiment of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the technical gist of the present invention.

10: Energy storage device, 20: Substation,
30: AC-based high-speed railway energy storage for substation,
32: battery, 34: transformer,
36: power conversion device, 38: cell inverter,
40: Demand power calculation unit, 42: Control unit.

Claims (5)

An energy storage device (30) for an AC-based high-speed railway substation, which receives electric power from a high-speed railway substation (20) to charge a battery (32) and supplies electric power charged in the battery (32)
A power converter 36 for generating an alternating voltage through on / off switching operation in association with the high voltage AC voltage mediated by the battery 32 and the transformer 34;
A demand power calculation unit 40 for calculating a demand forecast, setting an operation strategy set value for the energy storage device, managing a reference power value for charging / discharging determination, and calculating and predicting a power demand through the reference power value;
And a controller (42) for comparing the output of the battery (32) and the output of the demand power calculator (40) to control the power converter (36) to perform power charging and discharging Energy storage for high speed railway substations. The method according to claim 1,
Characterized in that the power inverter (36) comprises a plurality of multilevel cell inverters (38) connected in series and made up of IGBTs. The method according to claim 1,
Wherein the power inverter (36) comprises a plurality of cell inverters connected in parallel to divide the rated capacity of the device by 1 / N. The method according to claim 1,
The demand power calculation unit 40 calculates a daily demand power demand based on a load pattern of a substation and a schedule of train operation to predict a demand and the load pattern is a load pattern for the same past date target, And the first and second reference powers that are the reference of charge and discharge due to the demand calculation are calculated. The method according to claim 1,
The control unit 42 determines whether the current time is a dischargeable time zone or a chargeable time zone when the battery charge amount and the load amount signal are received every hour, and when the current time is a rechargeable time zone, If the current time zone is a dischargeable time, the second reference power and the current load amount are compared with each other. If the current charging time is shorter than the current charging time, Standby, and / or protection operation of the AC-based high-speed railway substation.

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