WO2012037722A1

WO2012037722A1 - Electrical vehicle charging automation system and controlling method thereof

Info

Publication number: WO2012037722A1
Application number: PCT/CN2010/077197
Authority: WO
Inventors: Zhao Wang; Yao Chen; Simon Felsenstein
Original assignee: Abb Research Ltd.
Priority date: 2010-09-21
Filing date: 2010-09-21
Publication date: 2012-03-29

Abstract

An electrical vehicle charging automation system and a controlling method thereof are provided. The system comprises at least one charger (61) and a controller (41, 51). The controller (41, 51) which is a central controller or a distributed controller comprises: a charging and discharging management module (414, 514) for managing the charging and discharging of the charger (61); a data module (415, 515) for storing and sharing information; an interface (416, 516) connected to a converter of the charger (61); a management module (411, 511) and a human machine interface (410, 510) for supervisory and management; a protection and control module (413, 513) for protecting and controlling electrical vehicle charging stations; and a coordination module (412, 512) for coordinating the controller (41, 51) with a distribution management system (31) connected to the electrical vehicle charging automation system. The method comprises the step: controlling the active power output of the charger (61) according to the real-time information collected from the charger (61) and/or the frequency or active power requirement from the distribution management system.

Description

An Electrical Vehicle Charging Automation System and the

Method Thereof

FIELD OF THE INVENTION

This invention relates to the field of power system, and more particularly to an electrical vehicle charging automation system.

BACKGROUND OF THE INVENTION

Electrical vehicle industry is undergoing rapid growth in response to the urgent needs for the climate change mitigation, the sustainable economy and the society development. Take China for example, it is estimated that the total vehicle population will reach 407-528 million in the year 2030, which means approximately 0.7-1 .3 billion ton crude oil consumption and 2.1 -3.8 billion ton C0₂ emission.

To maintain the sustainable society and the economy development, the electrical vehicles will take the place of the internal combustion engine vehicle. Estimated by some consultancy companies, the electrical vehicle market volume in China will reach up to 0.7 ~ 1 .5 trillion RMB in 2030.

However, a major new challenge for the electric power systems gradually reveals itself, i.e. the integration of a substantial number of electrical vehicles into the electric grid in the future. With the wide applications of the electrical vehicle charging units, their impacts on power systems especially on the distribution networks will gradually become the major concerns. To minimize the impact of large-scale electrical vehicle charging to existing distribution network, a hierarchical electrical vehicle charging management system is needed to realize the coordination among the distributed controllers (for the charger, the Energy Storage System or the Distributed Energy Resource), the controllers for station level and the Distribution Management System. SUMMARY OF THE INVENTION

To mitigate the impacts of large-scale electrical vehicle integration to the power system, the present invention provides an electrical vehicle charging automation system and the method thereof.

According to one aspect of the invention, an electrical vehicle charging automation system is provided. The system comprises at least one charger. It further comprises a controller. The controller comprises a charging and discharging management module for managing the charging and discharging of the chargers; a data module for storing and sharing information; and an interface to the converter of the charger.

According to a preferred embodiment of the present invention, the controller further comprises a management module and a human machine interface for supervisory and management; a protection and control module for protecting and controlling of the electrical vehicle charging station.

According to the preferred embodiment, the electrical vehicle charging automation system connects to a distribution management system. The controller further comprises a coordination module for coordinating the controller with the distribution management system.

The electrical vehicle charging automation system further comprises an Energy Storage

System and/or a Distributed Energy Resource. The interface to the converter of the charger is also the interface to the converter of Energy Storage System and the interface to the converter of the Distributed Energy Resource.

According to one preferred embodiment, said controller is a central controller. The central controller is connected with the converter of the charger and the converter of the Energy Storage System and/or the converter of the Distributed Energy Resource.

According to another preferred embodiment, said controller is a distributed controller. The distributed controller is a charger controller or an Energy Storage System controller or a Distributed Energy Resource controller.

According to the other aspect of the invention, a method of electrical vehicle charging automation is provided.

According to one preferred embodiments, the method comprises the following steps: 1 ) creating a controller as described above; 2) controlling the active power output of the charger according to the real-time information collected from the charger and/or the frequency or active power requirement from the distribution management system.

The active power output controlling comprises the direction controlling and the magnitude controlling and the changing rate controlling. The real-time information is collected by the following steps: 1 ) collecting real-time battery data and active power outputs from the charger; 2) calculating the available power capacity of the charger; and 3) sharing the information with distribution management system.

The method further comprises the following steps: the distribution management system calculates the frequency or active power requirement and sends it to the controller. The controller calculates active power reference according to the frequency or active power requirement from the distribution management system or the setting of the controller.

According to another preferred embodiments, the method comprises the following steps: 1 ) creating a controller as described above; 2) controlling the reactive power output of the charger according to the real-time information collected from the charger and/or the voltage or reactive power requirement from the distribution management system.

The reactive power output controlling comprises the direction controlling and the magnitude controlling and the changing rate controlling. The real-time information is collected by the following steps: 1 ) collecting real-time active and reactive power outputs from the charger; 2) calculating the available power capacity of the charger; and 3) sharing the information with distribution management system.

The method further comprises the following steps: the distribution management system calculates the voltage or reactive power requirement and sends it to the controller. The controller calculates reactive power reference according to the voltage or reactive power requirement from the distribution management system or the setting of the controller.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention will be explained in more details in the following description with reference to preferred exemplary embodiments which are illustrated in the drawings, in which:

Fig. 1 is a single line diagram of electrical vehicle charging station or region;

Fig. 2 is the central control architecture of electrical vehicle charging station according to the first preferred embodiment;

Fig. 3 shows the structure of the central controller of the electrical vehicle charging automation system;

Fig. 4 shows the information flows of electrical vehicle charging automation system according to the first preferred embodiment;

Fig. 5 is the distributed control architecture of electrical vehicle charging station according to the second preferred embodiment;

Fig. 6 shows the structure of the distributed controller of the electrical vehicle charging automation;

Fig. 7 shows the information flows of electrical vehicle charging automation system according to the second preferred embodiment;

Fig. 8 shows different operation statuses of the electrical vehicle charging station;

Fig. 9 shows the transition among the four possible operation modes of electrical vehicle chargers. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to the above-mentioned figures, preferred embodiments of the present invention are provided.

The electrical vehicle charging stations or regions are normally connected to the distribution network as shown in Figure 1 , wherein a plurality of low voltage AC/DC converters for electrical vehicle (EV) battery charging or discharging will be integrated into the medium voltage switchgears through step-up transformers. The distribution network 1 gets power from the transmission station and dispatches the power through the feeders. The electrical vehicle charging station 2 or region gets power from the feeder and transforms it to low voltage level, and then converts AC to DC to charge the batteries through the chargers. The Energy Storage System (ESS) or the Distributed Energy Resource (DER) could also be connected to the local grid. The electrical vehicle charging station 2 or region could have different topologies: 1 ) each charger, Energy Storage System or Distributed Energy Resource has an AC/DC converter, through which they can directly connect with the transformers. 2) Each charger, Energy Storage System or Distributed Energy Resource are connected to the DC bus via a DC/DC converter. The DC bus is powered by a large AC/DC converter which is connected to the transformer.

Figure 2 and Figure 3 show the structure of one preferred embodiment of the present invention. The electrical vehicle charging automation system comprises a central controller 41 . The electrical vehicle charging automation system is connected with the Distribution Management System (DMS) 31 . It comprises a plurality of chargers 61 and may also comprise an Energy Storage System 62 and/or a Distributed Energy Resource 63. From control point of view, there will be distributed converters inside each chargers 61 , Energy Storage System 62, and Distributed Energy Resource 63. As shown in Figure 3, the central controller 41 comprises a charging and discharging management module 414 for managing the charging and discharging of the chargers 61 ; a data module 415 for storing and sharing information; and an interface 416 to the converter of the charger 61 . The central controller 41 further comprises a management module 411 and a human machine interface 410 for supervisory and management; a protection and control module 413 for protecting and controlling of the electrical vehicle charging stations; a coordination module 412 for coordinating the central controller 41 with the distribution management system 31 , and an interface 417 to the Distribution Management System 31 .

The electrical vehicle charging automation system is based on Multi-Agent System, in which the Distribution Management System 31 could be an agent DAG. For the charging station, the central controller 41 could be an agent CAG, which gives overall station area control and optimization. As the central controller 41 fulfils a centralized control, it can directly control the distributed converters of the chargers 61 , the Energy Storage System 62 and the Distributed Energy Resource 63.

Hierarchical control method of electrical vehicle charging station can be realized based on such control architecture. Figure 4 shows the necessary information flow among distributed converters, CAG and DAG. The method of electrical vehicle charging automation comprises the step of controlling the active power output of the charger 61 according to the real-time information collected from the charger 61 and/or the frequency or active power requirement from the distribution management system 31 . The active power output controlling comprises the direction controlling and the magnitude controlling and the changing rate controlling. The real-time information is collected by the following steps: 1 ) collecting real-time battery data and active power outputs from the charger 61 ; 2) calculating the available power capacity of the charger; and 3) sharing the information with distribution management system 31 . The controller 41 calculates active power reference according to the frequency or active power requirement from the distribution management system 31 or the setting of the controller 41 .

The method of electrical vehicle charging automation further comprises the step of controlling the reactive power output of the charger according to the real-time information collected from the charger 61 and/or the voltage or reactive power requirement from the distribution management system 31 . The reactive power output controlling comprises the direction controlling and the magnitude controlling and the changing rate controlling. The real-time information is collected by the following steps: 1 ) collecting real-time active and reactive power outputs from the charger 61 ; 2) calculating the available power capacity of the charger; and 3) sharing the information with distribution management system 31 . The distribution management system 31 calculates the voltage or reactive power requirement and sends it to the controller 41 . The controller 41 calculates reactive power reference according to the voltage or reactive power requirement from the distribution management system 31 or the setting of the controller 41 .

The distributed converters will send on-line information to the central controller 41 , including current, voltage, and others. The central controller 41 will use the on-line information together with local information to generate the whole station measurement, power quality and metering, and then send them to the Distribution Management System 31 . The Distributed converters will send the battery capacity to the central controller 41 . The central controller 41 uses battery capacity information to generate load information, generation information and their forecast, and then sends them to the Distribution Management System 31 .

The protection operation of the central controller 41 will be sent to Distribution Management System 31 to trigger its feeder automation function. The feeder automation of Distribution Management System 31 will generate the active power and frequency requirement/command and feedback to the central controller. The central controller gets the active power and frequency requirement from Distribution Management System, and performs local active power and frequency control, and then sends the control command to the distributed converters. The distributed converters will execute the control command from the central controller 41 .

The Distribution Management System 31 will perform voltage & Var optimization, generate the voltage & Var requirement for each electrical vehicle charging automation system, and send the voltage & Var requirement to them one by one. The central controller 41 of electrical vehicle charging automation gets the voltage & Var requirement from the Distribution Management System, performs local voltage and & Var optimization, and sends the control command to the distributed converters. The distributed converters will execute the control command from the central controller 41 . The central controller 41 will perform local station charging and discharging management together with distributed controllers.

Figure 5 shows another preferred embodiment of the electrical vehicle charging automation system. The system comprises distributed controllers 51 instead of a central controller 41 . The distributed controllers 51 could be agents PAG, EAG, and RAG, which could directly coordinate with each other and DAG to fulfill distribution network level optimization. The electrical vehicle charging automation system comprises a plurality of chargers 61 and may also comprise an Energy Storage System 62 and/or a Distributed Energy Resource 63 and is connected with Distribution Management System (DMS) 31 . The charger controller 501 , the Energy Storage System controller 502 and Distributed Energy Resource controller 503 (the distributed controllers together with agent functions) will directly coordinate with DAG.

As shown in Figure 6, the distributed controller 51 comprises a charging and discharging management module 514 for managing the charging and discharging of the chargers 61 ; a data module 515 for storing and sharing information; and an interface 516 to the converter of the charger 61 . The distributed controller 51 further comprises a station management module 511 and a human machine interface 510 for supervisory and management; a protection and control module 513 for protecting and controlling of the electrical vehicle charging stations; a coordination module 512 for coordinating the distributed controller 51 with the distribution management system 31 , and an interface 517 to the Distribution Management System 31 . In case the electrical vehicle charging automation system comprising an Energy Storage System 62 and/or a Distributed Energy Resource 63, the distributed controller 51 further comprises an interface to the other distributed controllers 518.

Figure 7 shows the necessary information flow among distributed controllers 51 , PAG and the distributed converters of the chargers 61 , the Energy Storage System 62 and/or the Distributed Energy Resource 63.

Figure 8 shows possible operation statuses of electrical vehicle charging stations. Generally it has three statuses in a local distribution network, including isolate status which means disconnected from the grid; idle status which means connected to the grid without any power exchange; and charging/discharging status which means connected to the grid with active/reactive power exchange. The transitions among these three statuses are also given in this figure.

The electrical vehicle charging/discharging process starts from the isolated status. When the main circuit breaker closed, the electrical vehicle charging station transforms from isolated status to idle status. When the main circuit breaker opened and the electrical vehicle charging station is in idle status, the electrical vehicle charging station could transform back to isolated status. When having active power charging requirement, active power generation requirement, or reactive power supporting requirement, and the electrical vehicle charging station is in idle status, it will transform from idle status to charging/discharging status. When there is no requirement, it could transform back to idle status. When main circuit breaker opened and the electrical vehicle charging station is in charging/discharging status, it could transform to isolated status.

Figure 9 further illustrates the four possible operation modes of chargers according to the sign of active and reactive power, where positive active power indicating resistant active power when charging the battery; negative active power indicating regenerative active power when discharging the battery; positive reactive power indicating inductive reactive power with the current waveform lagging the voltage waveform by 90 degrees; negative reactive power indicating capacitive reactive power with the current waveform leading the voltage waveform by 90 degrees.

Power converters which can achieve all the four operation modes can be regarded to have four-quadrant operation capability. The four quadrants are also divided according to the sign of active and reactive power. Power converters consist of controllable power electronics devices can realize four-quadrant operation by changing the switching commands of power electronics devices according to the control commands of active power and reactive power. Transitions between any two operation modes are also considered to be achievable as shown in Figure 9.

The electrical vehicle charging automation system and the method have the following advantages:

1 ) Optimized charging/discharging management so as to minimize the impact of large- scale electrical vehicle integration to the existing distribution network;

2) Coordination between the electrical vehicle charging automation system and the Distribution Management System for grid-friendly charging and discharging, such as peak shaving, power flow optimization, grid-side frequency regulation, etc;

3) Coordination between the electrical vehicle charging automation and the Distribution Management System for local grid power quality improvement, such as voltage fluctuation suppression, reactive power compensation, etc.

Though the present invention has been described on the basis of some preferred embodiments, those skilled in the art should appreciate that those embodiments should by no means limit the scope of the present invention. Without departing from the spirit and concept of the present invention, any variations and modifications to the embodiments should be within the apprehension of those with ordinary knowledge and skills in the art, and therefore fall in the scope of the present invention which is defined by the accompanied claims.

Claims

1 . An electrical vehicle charging automation system comprising at least one charger (61 ); characterized in that

it further comprises a controller (41 , 51 ); said controller (41 , 51 ) comprises

a charging and discharging management module (414, 514) for managing the charging and discharging of the chargers (61 );

a data module (415, 515) for storing and sharing information; and

an interface (416, 516) to the converter of the charger (61 ).

2. The electrical vehicle charging automation system according to claim 1 , characterized in that said controller (41 , 51 ) further comprises

a management module (411 , 511 ) and a human machine interface (410, 510) for supervisory and management;

a protection and control module (413, 513) for protecting and controlling of the electrical vehicle charging stations.

3. The electrical vehicle charging automation system according to claim 1 , characterized in that it connects to a distribution management system (31 ); the controller (41 , 51 ) further comprises a coordination module (412, 512) for coordinating the controller (41 , 51 ) with the distribution management system (31 ).

4. The electrical vehicle charging automation system according to any one of claim 1 to 3, characterized in that it further comprises an Energy Storage System (62) and/or a Distributed Energy Resource (63); said interface (416, 516) to the converter of the charger (61 ) is also the interface to the converter of Energy Storage System (62) and the interface to the converter of the Distributed Energy Resource (63).

5. The electrical vehicle charging automation system according to claim 4, characterized in that said controller is a central controller (41 ), said central controller (41 ) is connected with the converter of the charger (416) and the converter of the Energy Storage System (62) and/or the converter of the Distributed Energy Resource (63).

6. The electrical vehicle charging automation system according to any one of claim 4, characterized in that said controller is a distributed controller (51 ); said distributed controller (51 ) is a charger controller (501 ) or an Energy Storage System controller (502) or a Distributed Energy Resource controller (503).

7. A method of electrical vehicle charging automation characterized in that comprising the following steps: creating a controller (41 , 51 ) of any one of claim 1 to 3;

controlling the active power output of the charger (61 ) according to the real-time information collected from the charger (61 ) and/or the frequency or active power requirement from the distribution management system (31 ).

8. The method according to claim 7, characterized in that said active power output controlling comprises the direction controlling and the magnitude controlling and the changing rate controlling.

9. The method according to claim 7, characterized in that said real-time information is collected by the following steps:

collecting real-time battery data and active power outputs from the charger (61 );

calculating the available power capacity of the charger; and

sharing the information with distribution management system (31 ).

10. The method according to claim 9, characterized in that it further comprises the following step:

the distribution management system (31 ) calculates the frequency or active power requirement and sends it to the controller (41 , 51 ).

11 . The method according to claim 9, characterized in that it further comprises the following step:

the controller (41 , 51 ) calculates active power reference according to the frequency or active power requirement from the distribution management system (31 ) or the setting of the controller (41 , 51 ).

12. A method of electrical vehicle charging automation characterized in that comprising the following step:

creating a controller (41 , 51 ) of any one of claim 1 to 3;

controlling the reactive power output of the charger according to the real-time information collected from the charger (61 ) and/or the voltage or reactive power requirement from the distribution management system (31 ).

13. The method according to claim 12, characterized in that said reactive power output controlling comprises the direction controlling and the magnitude controlling and the changing rate controlling.

14. The method according to claim 12, characterized in that said real-time information is collected by the following steps:

collecting real-time active and reactive power outputs from the charger (61 );

calculating the available power capacity of the charger; and sharing the information with distribution management system (31 ).

15. The method according to claim 14, characterized in that it further comprises the following steps:

the distribution management system (31 ) calculates the voltage or reactive power requirement and sends it to the controller (41 , 51 );

the controller (41 , 51 ) calculates reactive power reference according to the voltage or reactive power requirement from the distribution management system (31 ) or the setting of the controller (41 , 51 ).