Development of the Information Layer for the V2G Framework Implementation
This activity has focused on various design and implementation issues for the recently proposed conceptual framework for the integration of battery vehicles or BVs into the grid. This so-called vehicle-to-grid notion is often referred to as V2G. A key challenge in the implementation of this conceptual construct is the design and development of the information layer: the establishment of the infrastructural computer/communication/ control network for the integration of the aggregated BVs into the grid. This layer plays a critical role in the provision of the flows of information, control commands and monitoring measurement data required by the various entities that participate in the operation of the V2G concept implementation. The project developed an implementable design of the information layer with particular focus on the cybersecurity protection.
The activity entailed a solid understanding and appropriate formulation of the requirements that the information layer must meet and the criticality of its role in the support of the new player on the grid scene – the Aggregator – to collect data from large numbers of aggregated BVs and to carry out its functions effectively and in a timely manner. BVs can serve as distributed storage, generation and load resources, and as a result, have to transmit their information, such as instantaneous state of charge (s.o.c.), duration of availability (as a resource) or requirement (as a load), minimum charge requirement, and other BV owner preferences. This information is aggregated at each parking lot or load subregion and transmitted further up the control chain. The importance of the cyber security aspects of the information layer arises because each EV becomes, in effect, a portal into the power grid. The lack of adequate security measures is a major impediment to the effective integration of BVs into the grid.
The solid understanding of the nature and scope of the communication and information requirements led in a logical way to a comprehensive set of requirements for the development of the design of the layer with the incorporated schemes to address its cyber security aspects. The V2G communication layer requires extensive bi-directional communication and, therefore, is vulnerable to cyber-attacks. We have shown that the cyber security protection of the V2G communication layer can be cast into a form so that the Least Privilege Architecture (LPA) provides an appropriate structure to protect the cyber security of the grid. The LPA framework provides a mechanism that greatly facilitates the work of the BV Aggregator, the critical entity in the integration of the EVs into the grid. Specifically, the architecture enables the decomposition of the Aggregator’s functions into logically disjoint services. These mechanisms effectively limit the privileges of each service so that the entity interfacing with the Aggregator can only access the functions and data it needs to fully complete its tasks. The proposed approach minimizes the impacts of a successful attack on each service provided by the Aggregator. In this way the cyber security of the information layer is effectively addressed. The design is a key accomplishment of this activity and the protection against cyber threats ensures that the V2G integration protects the grid against potential cyber threats that may arise under the V2G arrangement.
A second major accomplishment is the extension of the information layer to develop a practical approach to collect taxes to replace the foregone revenues from gasoline taxes. As the penetration of battery vehicles (BVs) deepens, there is clear consensus on the need to replace with an alternative collection system the tax revenues generated by gasoline sales. Such reduced revenues impact the funding for the highway and road systems of the nation. Our activities developed the methodology and addressed the data collection/processing/storage issues of such revenues. The collection of vehicle use data, however, has major repercussions on privacy issues and is accompanied by major concerns with the use of the data. We also addressed the security of the system and the data collection procedure, as well as data tampering issues.
The replacement tax used is the vehicle traveled miles (VMT) tax, which is imposed on the basis of the monitored vehicle road usage and is viewed widely as a practical approach to manage the collection of taxes for road utilization. VMT can be supported by data from odometer and GPS telemetry; however, the collection and processing of such data is privacy invasive. The design developed is for a privacy preserving VMT tax. The proposed approach uses vehicle-based tax calculations and an additive secret-sharing scheme that protects the BV user’s privacy with the accurate allocation of the tax revenues to the appropriate tax jurisdictions. As long as the BV calculations and sensors are adequately protected against tampering, the design and the scheme provide strong and scalable privacy protection. The algorithms we developed use data from trusted inertial motion sensors to detect spoofing and its validation in our studies ensures tamper-resistance against GPS spoofing and jamming. We completed the development and testing of a proof-of-concept in the form of an Android app. The app collects and stores location data from the smartphone and analyzes the stored driving data using the dedicated algorithm implemented. Moreover, the app corroborates with the GPS data the turns observed from the gyroscope measurements. We also implemented a technique, implemented in Java, to preserve location privacy. For scalability purposes, we verified that the computation time of the system increases linearly with the number of cars. The design and the proof-of-concept implementation constitute an important contribution to the development of a practical scheme to replace the gasoline tax revenues.
The V2G secure information layer and the secure PPVMT scheme are key advancements in the state of the art of V2G implementation. The expected proliferation of BVs will bring major impacts to the electricity grid. The two contributions will propel this proliferation and allow the effective harnessing of the BVs to effectively utilize the V2G framework so as to create a cleaner environment and work symbiotically with the electricity grid.