WO2015111144A1

WO2015111144A1 - Power supply system and energy management system used in same

Info

Publication number: WO2015111144A1
Application number: PCT/JP2014/051180
Authority: WO
Inventors: 雅也奥薗
Original assignee: 株式会社日立製作所
Priority date: 2014-01-22
Filing date: 2014-01-22
Publication date: 2015-07-30
Also published as: JPWO2015111144A1; JP5994027B2

Abstract

　A power supply system in which a lead storage cell is used, wherein stable and highly efficient control is performed in consideration of the properties of the lead storage cell and the supply-demand balance. A lead storage cell (320) stores power generated by a distributed power source (310) and power received from a power system. An energy management system (EMS) (100) forecasts the amount of power generated by the distributed power source (310) and the amount of power demanded by load devices (400-600), and correspondingly calculates a target value for the operation voltage of the lead storage cell (320). A power conditioning system (PCS) (300) controls the input/output of power with respect to the distributed power supply (310) and the lead storage cell (320) so that the operation voltage of the lead storage cell (320) reaches the target value calculated by the EMS (100).

Description

Power supply system and energy management system used therefor

The present invention relates to a power supply system for equipment having a lead storage battery and an energy management system used therefor.

In recent years, reduction of carbon dioxide has been screamed worldwide due to global warming, and the shift to renewable electricity is progressing reflecting the depletion of fossil fuels. Renewable power is generated based on natural energy such as sunlight and wind power, so the amount of power generation is unstable. Therefore, using a secondary battery, an energy management system that can store surplus power when the generated power exceeds demand power and supply the stored power when the demand power exceeds generated power ( EMS) is drawing attention. As a secondary battery in such a case, a lead-acid battery has a lower price per capacity than other secondary batteries, and is widely used from consumer use to industrial use.

As a method for controlling a secondary battery connected to an electric power system, there is a technique described in Patent Document 1. In the same document, for each of a plurality of batteries, communication characteristic detecting means for detecting characteristics of a communication path between the battery and the battery control system, and predetermined communication characteristics from a plurality of batteries based on the detection result. It is described that a battery that uses a communication path having characteristics within a range is selected as a candidate for adjusting the power of the power system, and an operation instruction that instructs charging or discharging is output and controlled.

International Publication WO2013 / 042474

However, the secondary battery control method according to the technique disclosed in Patent Document 1 determines a battery that satisfies a predetermined communication characteristic as a battery candidate for adjustment, and has a characteristic characteristic of a lead storage battery as a secondary battery. Not considered. That is, in the lead storage battery, the chargeable / dischargeable power decreases depending on the operating state (storage battery voltage during operation), and the lead battery may not be able to exhibit the original adjustment capability. Furthermore, the control method by patent document 1 controls charging / discharging of a secondary battery based on the operation state of the present installation. Therefore, if the supply and demand balance of the entire facility fluctuates, it may not be able to follow this and may deviate from stable control.

Therefore, the present invention has been made in view of the above-described problems, and the object of the present invention is to provide a highly efficient and stable power supply system using a lead storage battery in consideration of the characteristics and supply / demand balance of the lead storage battery. It is to perform proper control.

In order to solve the above problems, the present invention has the following configuration. In a power supply system that receives power from a power system and a distributed power source and supplies power to a load device, a lead storage battery that stores received power from the power system and power generated by the distributed power source, and a distributed power source and a lead storage battery A power adjustment device (PCS) that controls input / output of power and an energy management system (EMS) that monitors the power and voltage of each device in the system and controls the power adjustment device. The energy management system includes a generated power prediction unit that predicts the generated power amount of the distributed power source, a demand power prediction unit that predicts the demand power amount of the load device, and the predicted generated power amount and the required power amount. A storage battery target voltage calculation unit that calculates a target value of the operating voltage of the lead storage battery, and the power adjustment device is configured so that the operating voltage of the lead storage battery becomes a target value calculated by the energy management system. And control the power input and output of lead-acid battery.

According to the present invention, in a power supply system using a lead storage battery, even if the power supply / demand balance in the facility fluctuates, the charging / discharging capacity of the lead storage battery is set to be large, so that efficient and stable control is achieved. It can be performed.

The figure which shows the whole structure of the electric power supply system which concerns on embodiment of this invention. The figure which shows the relationship between the electric power which can be charged / discharged of a lead storage battery, and a storage battery voltage. The figure which shows the target voltage Vt1 set to the lead acid battery in case 1. FIG. The figure which shows the target voltage Vt2 set to the lead acid battery in case 2. FIG. The figure which shows the target voltage Vt3 set to the lead acid battery in case 3. FIG. The figure which shows the target voltage Vt4 set to the lead acid battery in case 4. FIG.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing an overall configuration of a power supply system according to an embodiment of the present invention. In this embodiment, a lead storage battery is used as the secondary battery.

The power supply system is an energy management system (hereinafter abbreviated as EMS) 100 that monitors and controls the power and voltage of each device in the system, and an interconnection point that receives commercial power from the power company. 200, a distributed power source 310 such as solar power generation or wind power generation, a lead storage battery 320 that stores electric power generated by the distributed power source 310 or received power from the interconnection point 200, and distributed based on a control command from the EMS 100 A power adjustment device (hereinafter abbreviated as PCS) 300 that controls input / output of power from the power source 310 and the lead storage battery 320.

In addition, as an example of equipment on the power demand side, a car rental service and a car sharing service are assumed, in which an electric vehicle equipped with a secondary battery is lent. That is, a DC charger 400 that inputs AC power, converts the DC power to charge the electric vehicle 600, a DC discharger 410 that AC converts DC power discharged from the electric vehicle 600, and the electric vehicle 600 has a voltage of 200V or 100V. An AC charger 420 that charges with AC power, an AC discharger 430 that discharges with 200V or 100V AC power from the electric vehicle 600, an equipment load 500 that consumes power for lighting and equipment operations used in the equipment, etc. Is connected.

An energy management system (EMS) 100 includes an input unit 110 that inputs the amount of power and voltage of each device, a generated power prediction unit 120 that predicts the amount of power generated by the distributed power source 310, and each device on the load side (DC charger) 400, DC discharger 410, AC charger 420, AC discharger 430, equipment load 500), the power demand prediction unit 130 for calculating the amount of power required, and the optimal storage battery voltage target value for the lead storage battery 320. A storage battery target voltage calculation unit 140 and an output unit 150 that outputs a control signal such as a storage battery target voltage to the power adjustment device (PCS) 300 are provided. Here, the power demand prediction unit 130 uses the DC charger 400 and the AC charger 420 for the demand of the electric vehicle 600 based on the use reservation information of the service (car rental service or car sharing service) performed by the facility. Electric power can be predicted.

The feature of this embodiment is that the energy management system (EMS) 100 calculates the optimum operating voltage (target voltage) of the lead storage battery 320 based on the predicted generated power value and the predicted power demand value, and the power adjustment device ( PCS) 300. The power conditioner (PCS) 300 controls power input / output of the distributed power supply 310 and the lead storage battery 320 so that the voltage of the lead storage battery 320 becomes the target voltage received from the EMS 100.

FIG. 2 is a diagram showing the relationship between the chargeable / dischargeable power of the lead storage battery and the storage battery voltage. In the case of the lead storage battery 320, the chargeable / dischargeable power has a unique property that it depends on the storage battery voltage. The dischargeable power 700 is small when the storage battery voltage is low, increases as the storage battery voltage increases, reaches a maximum value at the position 710, and does not change even if the storage battery voltage increases further. On the other hand, the rechargeable power 800 is small when the storage battery voltage is low, increases as the storage battery voltage increases, reaches a maximum value at a position indicated by reference numeral 810, and rapidly decreases as the storage battery voltage increases further. The maximum dischargeable power position 710 and the maximum chargeable power position 810 do not match, and the maximum chargeable power position 810 is slightly lower than the maximum dischargeable power position 710.

In this way, the chargeable / dischargeable power of the lead storage battery 320 depends on the storage battery voltage, so the performance of the lead storage battery 320 is maximized by setting and using the storage battery voltage so that the chargeable / dischargeable power is maximized. it can. However, there is a difference in the optimum voltage value between charging and discharging. In this embodiment, priority is given to the characteristics of the chargeable power 800 having a steeper change gradient, and the storage battery voltage that gives the maximum point 810 is set as the optimum voltage Vopt. At the optimum voltage Vopt, the other dischargeable electric power 700 is not a maximum value but is a relatively high value. Therefore, it can be said that the optimum voltage Vopt satisfies both the charging and discharging conditions.

On the other hand, the lead storage battery 320 charges surplus power out of the power generated by the distributed power source 310 or supplies (discharges) power used by load devices (DC charger 400, AC charger 420, equipment load 500). It is necessary to do. Therefore, the storage battery voltage is not fixed to a constant value, but varies within a certain range. In this case, it is preferable in terms of efficiency that the operating range 900 is set before the optimum voltage Vopt of the lead storage battery 320. This is because when the optimum voltage Vopt (maximum point 810) is exceeded, the chargeable power 800 rapidly decreases. In addition, the voltage range of the operating range 900 varies depending on the charge / discharge amount of the lead storage battery 320.

Thus, in this embodiment, the voltage operating range 900 of the lead storage battery 320 is set as close as possible to the optimum voltage Vopt. Therefore, in the EMS 100, the storage battery target voltage calculation unit 140 calculates the operation target voltage Vt of the lead storage battery 320 based on the generated power predicted value from the generated power prediction unit 120 and the demand power predicted value from the demand power prediction unit 130. To PCS300. The PCS 300 sets a target voltage Vt for the lead storage battery 320 and performs charge / discharge control of the lead storage battery 320. The target voltage Vt is set as follows according to the generated power predicted value and the demand power predicted value.

<Case 1> The predicted generated power value is small and the predicted power demand value is also small.
FIG. 3 is a diagram showing a target voltage Vt1 set for the lead storage battery in case 1. FIG. The target voltage Vt1 in case 1 is set in the vicinity of the optimum voltage Vopt, as indicated by reference numeral 910. In this case, since both the predicted power generation value and the predicted power demand value are small, the fluctuation of the storage battery voltage is small, and the operating point can be kept near the optimum voltage Vopt.

<Case 2> When the predicted power generation value is large and the predicted power demand value is small.
FIG. 4 is a diagram showing a target voltage Vt2 set for the lead storage battery in case 2. As shown in FIG. The target voltage Vt2 in case 2 is set at a position lower than the optimum voltage Vopt, as indicated by reference numeral 920. In this case, the generated power prediction value is large, and surplus power of the power generated by the distributed power source 310 can be charged. Thereafter, the lead storage battery 320 is charged over time, and the storage battery voltage changes in the direction of the arrow 921, but is controlled so as not to exceed the optimum voltage Vopt indicated by reference numeral 922.

<Case 3> When the predicted power generation value is small and the predicted power demand value is large.
FIG. 5 is a diagram showing the target voltage Vt3 set for the lead storage battery in Case 3. FIG. The target voltage Vt3 in case 3 is set in the vicinity of the optimum voltage Vopt as indicated by reference numeral 930. This is because the predicted power demand is large, and discharge from the lead storage battery 320 to the load device is possible. Thereafter, the lead storage battery 320 is discharged over time, and the storage battery voltage changes in the direction of the arrow 931, for example, to a position indicated by reference numeral 932.

<Case 4> When the predicted generated power is large and the predicted power demand is large.
FIG. 6 is a diagram showing a target voltage Vt4 set for the lead storage battery in case 4. FIG. The target voltage Vt4 in case 4 is set at a position lower than the optimum voltage Vopt, as indicated by reference numeral 940. In this case, both the predicted generated power value and the predicted power demand value are large, and both the charging operation and the discharging operation of the lead storage battery 320 are enabled. Thereafter, during the period in which the charging operation wins over time, control is performed so as to change in the direction of arrow 941 and not exceed the optimum voltage Vopt indicated by reference numeral 942. On the contrary, in the period in which the discharge operation is prevailing, the direction changes in the direction of the arrow 943 and drops to the position indicated by the reference numeral 944, for example.

In the case 2 and the case 4 described above, the target voltage Vt is set lower than the optimum voltage Vopt, but how much lower the target voltage Vt is set is determined by the storage battery target voltage calculation unit 140. That is, the target voltage Vt is determined by predicting the difference amount (surplus power) between the generated power predicted value and the demand power predicted value. Further, it goes without saying that whether or not the predicted charging power or discharging power can be handled by the current storage battery voltage of the lead storage battery 320 is taken into consideration.

In any of the cases described above, the lead storage battery 320 operates in a range near the optimum voltage Vopt, so that the chargeable / dischargeable power of the lead storage battery 320 can be increased, and a power supply system with high power efficiency is realized. Moreover, since the operating point of the lead storage battery 320 is set by predicting the generated power and the demand power, stable control can be performed even if the supply-demand balance fluctuates.

In the embodiments described above, various inventions can be formed by appropriately combining a plurality of components. That is, even if some constituent elements are deleted from all the constituent elements shown in the embodiment or a plurality of constituent elements are combined, it is within the scope of the present invention.

100: Energy management system (EMS),
110: input unit,
120: Generated power prediction unit,
130: Power demand prediction unit,
140: Storage battery target voltage calculation unit,
150: output unit,
200: connection point
300: Power conditioner (PCS),
310: distributed power supply,
320: lead acid battery,
400: DC charger,
410: DC discharger,
420: AC charger,
430: AC discharger,
500: equipment load,
600: electric car,
700: Dischargeable power,
710: Maximum dischargeable power position,
800: rechargeable power,
810: Maximum chargeable power position,
910: Target voltage Vt1 (case 1),
920: Target voltage Vt2 (Case 2),
930: target voltage Vt3 (case 3),
940: target voltage Vt4 (case 4),
Vopt: optimal voltage.

Claims

In a power supply system that receives power from a power system and a distributed power source and supplies power to a load device,
A lead-acid battery that stores received power from the power system and power generated by the distributed power source; and
A power conditioner (PCS) that controls input / output of power of the distributed power source and the lead acid battery;
An energy management system (EMS) that monitors the power and voltage of each device in the system and controls the power conditioner;
The energy management system
A generated power prediction unit for predicting the generated power amount of the distributed power source;
A demand power prediction unit for predicting the demand power amount of the load device;
A storage battery target voltage calculation unit that calculates a target value of the operating voltage of the lead storage battery according to the predicted amount of generated power and the amount of power for demand;
The power adjustment device controls input / output of power of the distributed power source and the lead storage battery so that an operating voltage of the lead storage battery becomes a target value calculated by the energy management system. system.
The power supply system according to claim 1,
When the storage battery voltage at which the rechargeable power of the lead storage battery is maximized is an optimum value,
The storage battery target voltage calculator of the energy management system is:
When the predicted power generation value is large and the predicted power demand value is small, the target value of the operating voltage of the lead storage battery is set to a value lower than the optimum value.
The power supply system according to claim 1,
When the storage battery voltage at which the rechargeable power of the lead storage battery is maximized is an optimum value,
The storage battery target voltage calculator of the energy management system is:
When the predicted generated power value is small and the predicted power demand value is large, the target value of the operating voltage of the lead storage battery is set to a value near the optimum value.
The power received by the power system and the power generated by the distributed power source are stored in a lead storage battery, and power is supplied to a load device via a power regulator (PCS) that controls input / output of the power of the distributed power source and the lead storage battery. An energy management system (EMS) used in a power supply system for supplying
A generated power prediction unit for predicting the generated power amount of the distributed power source;
A demand power prediction unit for predicting the demand power amount of the load device;
A storage battery target voltage calculation unit that calculates a target value of the operating voltage of the lead storage battery according to the predicted amount of generated power and amount of power for demand, and
The power adjustment device is configured to control input / output of power of the distributed power source and the lead storage battery so that an operating voltage of the lead storage battery becomes a target value calculated by the storage battery target voltage calculation unit. Energy management system.
In the energy management system according to claim 4,
When the storage battery voltage at which the rechargeable power of the lead storage battery is maximized is an optimum value,
The storage battery target voltage calculator is
When the predicted generated power value is large and the predicted power demand value is small, the target value of the operating voltage of the lead storage battery is set to a value lower than the optimum value.
In the energy management system according to claim 4,
When the storage battery voltage at which the rechargeable power of the lead storage battery is maximized is an optimum value,
The storage battery target voltage calculator is
When the predicted generated power value is small and the predicted power demand value is large, the target value of the operating voltage of the lead storage battery is set to a value near the optimum value.