Bidirectional AC V2G for Multifamily/Workplace Electric Vehicle Charging

Abstract

This invention is based on the availability of Electric Vehicles with onboard inverters and receptacles to supply significant amounts of AC power from the main propulsion batteries of the vehicles. It embodies a system comprising an apparatus and methods for bidirectionally connecting one or more electric vehicles at a workplace or multifamily residence to one or more distribution panels supplying critical loads and one or more panels supplying interruptible loads such that the vehicle(s) can supply back up power to critical loads during a grid outage. The bidirectional connection also enables V2G operation to enable energy arbitrage, demand response, and ancillary services to the grid.

Claims

1. An apparatus comprising; A plug, a cord and a remotely controllable connector to take electric energy from an electric vehicle, said electric vehicle being equipped to supply AC power via an onboard inverter from a main propulsion battery of the vehicle, A switch in the connector enabling the vehicle to feed remotely controllable amounts of electric power to a distribution panel to supply critical loads, which require back up power during grid outages, Said critical load panel being equipped with an automatic transfer switch to isolate it from an electric energy supply grid during grid outages, A remotely controllable Electric Vehicle Service Equipment supplied with electric power from a separate distribution panel providing AC electric energy to recharge the electric vehicle via the onboard charger of the vehicle, Control software to control said connector and said EVSE to accomplish various objectives, Communications and control equipment to enable said software to function.

2. The apparatus of claim 1 in which the switch in the connector is replaced by a semiconductor control device providing for a continuous and proportional flow of energy from the vehicle.

3. The apparatus of claim 1 in which a number of electric vehicles are connected to a single set of critical load and distribution panels.

4. The apparatus of claim 1 in which the control functions are performed remotely by an aggregator of several such systems.

5. The apparatus of claim 1 in which the EVSE provides electric energy to the vehicle through an SAE J-1772 standard cord and plug.

6. The method of installing and operating the apparatus of claim 1 in which when electric vehicles are plugged into the EVSEs they receive a minimum rate of charge that will maintain the communication between the vehicle and the EVSE, which can be increased to provide additional range for the EV or offset by withdrawals through the connector.

7. The method of installing and operating the apparatus of claim 1 in which electric energy can be withdrawn from the grid and used to recharge electric vehicles at times when it is available and inexpensive and can be resold to suppliers or users of electric energy at a price below the average price of electric energy.

8. The method of installing and operating the apparatus of claim 1 in which electric energy demand on the grid can be reliably reduced and capacity payments earned by a combination of reducing the rate of EV charging and/or returning energy to the grid.

9. The method of installing and operating the apparatus of claim 1 in which the rate of EV battery charge and discharge is modulated in response to requests from the grid ISO/RTO to provide frequency regulation service and revenue.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is a schematic diagram showing the apparatus of this invention applied to a building with panels for distribution of electric energy to critical loads and regular loads separated by an automatic transfer switch. The electric vehicle is charged by an EVSE powered by the regular load panel, and it can power the critical load panel from its on board inverter and AC receptacle during outages.

DETAILED DESCRIPTION OF THE INVENTION: THE PREFERRED EMBODIMENT

[0029] Electric vehicle 10 is powered by storage battery 12, which may have a capacity of a much as 100 kWh in long-range vehicles. Vehicle 10 also has an on board inverter 14 to provide AC power through receptacle 16 to operate power tools and the like. When parked for recharging receptacle 16 is connected by plug 18 to a controllable connector 22 to a critical loads panel 20. Connection 24 is shown as an electro mechanical relay, but is more properly a semiconductor relay that can be controlled to provide a proportional amount of power to the critical loads panel and on to the grid. Slots 26 are circuit breakers to individual loads which need to continue operating in an emergency such as emergency lighting, elevators and minimal ventilation. A number of vehicles 10 may be connected to one critical loads panel to ensure adequate endurance. Switch 28 is an automatic transfer switch to isolate the critical loads panel and its vehicle power supply in an outage.

[0030] Emergency load panel 20 and regular load panel 30 are powered from the grid, typically at 240 V or 208 V. One of the regular loads is the recharging of vehicle 10 via EVSE 32 and flexible cable and plug 34 to vehicle receptacle 36. The design and operating details of the EVSE and plug are typically specified in SAE Standard J-1772.sup.3. They provide AC power to on board charger 38, which rectifies it to DC power to charge battery 12. EVSE 32 needs to be remotely controllable, preferably to provide a proportional amount of power to the vehicle. Again a number of EVs can be charged from a single panel. .sup.3 SAE Surface Vehicle Recommended Practice, J-1772 SAE Electric Vehicle Conductive Charge Coupler, revised October, 2012.

[0031] EVSE 32 and connector 22 are remotely controlled by aggregator software 40 which may be located physically in a local microcontroller or remotely in the cloud. There are networks 50 designed to enable control of large numbers of EVSEs remotely over the Internet, either via a local WiFi connection or by cellular phone. One such is the JuiceNet maintained by ENEL-X Emobility.

[0032] When not in use vehicle 10 is plugged in to both to EVSE 32 and to connector 22. In this condition it can provide frequency regulation service. Typically grid operators need to give or get increments of electric power from second to second to maintain the grid frequency at exactly 60 Hz. There is a well-established market for providing this service in increments of 100 kW and getting paid for it through Curtailment Service Providers (CSPs). The operators qualify both generators and controllable loads, which can provide regulation services. The qualified entities then bid to provide services in the day-ahead market through the CSPs. Accepted bidders receive commands to increase or reduce availability of energy on the grid and are remunerated based on their performance. An aggregation of EVSEs can be controlled remotely to provide this service. This is Vehicle-to-Grid, or V2G operation.

[0033] To confirm that the agreed regulation service has been performed, it is necessary that the communication loop be completed from the individuals EVSEs back through the local controllers or the EVSE network to the aggregators, and on to the CSP and to the ISO/RTO for confirmation.

[0034] Capacity payments depend on the recipient's ability to demonstrate to the RTO that they can indeed increase output or reduce demand by the specified amount for a specified time, typically 12 hours in the summer, and do this reliably whenever required. For a managed load, this requires demonstrating that the load is real with reliable metering, and that it can be interrupted reliably. Normal electric vehicle charging does not fit this profile well because the charging load is distributed geographically and time wise, making it difficult to guarantee a stated reduction at a arbitrary time. With bidirectional capability it is much easier to comply with these requirements because the plugged in vehicles can either reduce charging rate if they are charging or deliver the same amount of power if they are full. In this way it is possible to guarantee compliance, especially if the vehicles are concentrated in a single location such as a multifamily residence.

[0035] The same capability makes it possible to perform actual energy arbitrage by charging vehicles as fast as possible when energy is cheap and returning it to the grid when it is expensive. The utilities frown on this practice and regulate to suppress it. A more acceptable practice is to control charging to occur at periods of low demand such as midnight to 6 AM. By doing so and acting as an energy broker to buy energy at that time, the aggregator can profitably resell energy to the customer or to a third party Load Serving Entity at a lower price than their average billing price.

[0036] Back up power is provided by this invention automatically. The EV is expected to be plugged in at all times when not in use, and to be charging when energy is available and reasonable in price. It will therefore have a considerable amount of energy on board except immediately after a several hundred-mile trip. If the power goes out, the automatic transfer switch automatically isolates the critical loads from the grid and leaves them connected to the vehicle with whatever energy it has on board. Typically a half charge will approach 50 kWh and with a number of vehicles connected this number will be more reliable. The typical outage is only minutes in duration, which will not be noticed. The more severe outages are those that last for days, and in those cases a bidirectional vehicle could actually go to a site with power, load up and bring it back to a site without power, providing irreplaceable and essential electric energy.

RELEVANT PREVIOUS LITERATURE

[0037] V2G is not a new concept and there are many patents and papers dealing with it since approximately 2000. One such.sup.4 is representative. It discloses an onboard inverter/charger to provide bidirectional power flow to/from a vehicle. There are stationary inverter chargers that perform the same function, such as those that were produced by Princeton Power Systems. The unique feature of this invention is to use the very recent availability of onboard inverters with high power capability to make available a simple and inexpensive control apparatus and method using the functions and equipment already provided by the vehicle manufacturer to achieve the same end at less cost. .sup.4 Patent Application 2013/0338527, “Apparatus for Bidirectional Electric Power Supply between Electric Vehicle and Smart Grid and Method of Bidirectionaly Supplying Electric Power Employing the Same” Kang J-J, Jun. 10, 2013

[0038] While the drawing and descriptions in this application are intended to be comprehensive, it will be understood by those skilled in the art that there are similar means to achieve the same ends, which fall within the claimed scope of this invention.