Sergejus Martinenas

Enhancing the Role of Electric Vehicles in the Power Grid: Field Validation of Multiple Ancillary Services

With increased penetration of distributed energy resources and electric vehicles (EVs), different EV integration strategies can be used for mitigating various adverse effects, and supporting the grid. However, the research regarding EV smart charging has mostly remained on simulations, whereas the experimental validation has rarely been touched upon. This paper focuses mainly on evaluating the technical feasibility of a series-produced EV to provide flexibility in real distribution grids. The implemented controller uses contemporary and widely supported standards for limiting the EV charging rate, which essentially means that it is applicable to any EV complying with IEC 61851 and SAE J1772 standards. The field test validation is conducted in a real Danish distribution grid with a Nissan Leaf providing three ancillary services through unidirectional ac charging, namely, congestion management, local voltage support, and primary frequency regulation. Several performance parameters, such as EV response time and accuracy, are assessed and benchmarked with current requirements. Ultimately, this paper aims to strengthen the applied research within the EV integration domain through validating smart grid concepts on original standard-compliant equipment.

Electric vehicle smart charging using dynamic price signal

With yearly increases in Electric Vehicle (EV) sales, the future for electric mobility continues to brighten, and with more vehicles hitting the roads every day, the energy requirements on the grid will increase, potentially causing low-voltage distribution grid congestion. This problem can, however, be resolved by using intelligent EV charging strategies, commonly referred to as Smart Charging. The basic approach involves modifying the default vehicle charging scheme of immediate charging, to a more optimal one that is derived from insight into the current state of the grid. This approach proposed in this paper, involves a real-time control strategy for charging the EV using a dynamic price tariff, with the objective of minimizing the charging cost. Two different charging scenario are investigated, and the results are verified by experiments on a real Electric Vehicle. Finally, the costs of the proposed solutions are compared to the default charging scheme.

Management of Power Quality Issues in Low Voltage Networks Using Electric Vehicles: Experimental Validation

As electric vehicles (EVs) are becoming more widespread, their high power consumption presents challenges for the residential low voltage networks, especially when connected to long feeders with unevenly distributed loads. However, if intelligently integrated, EVs can also partially solve the existing and future power quality problems. One of the main aspects of the power quality relates to voltage quality. The aim of this work is to experimentally analyze whether series-produced EVs, adhering to contemporary standard and without relying on any vehicle-to-grid capability, can mitigate line voltage drops and voltage unbalances by a local smart charging algorithm based on a droop controller. In order to validate this capability, a low-voltage grid with a share of renewable resources is recreated in SYSLAB PowerLabDK. The experimental results demonstrate the advantages of the intelligent EV charging in improving the power quality of a highly unbalanced grid.

Evaluation of electric vehicle charging controllability for provision of time critical grid services

Replacement of conventional generation by more stochastic renewable generation sources leads to reduction of inertia and controllability in the power system. This introduces the need for more dynamic regulation services. These faster services could potentially be provided by the growing number of electric vehicles. EVs are a fast responding energy resource with high availability. This work evaluates and experimentally shows the limits of EV charging controllability using widely supported IEC 61851 standard. The focus is put on EVs suitability for providing ancillary grid services with time critical requirements. Three different series produced EVs are tested. The experimental testing is done by using charging current controllability of built-in AC charger to provide a primary frequency regulation service with very dynamic input frequency. The results show that the controllability of most EVs is more than suitable for providing time critical grid services. Meanwhile, charging current ramping rates of recently produced EVs are potentially suitable to even provide synthetic inertia.

Economic comparison of electric vehicles performing unidirectional and bidirectional frequency control in Denmark with practical validation

The paper aims at investigating different methods, based on unidirectional charge and Vehicle-to-Grid (V2G), in order to evaluate and compare the potential economic revenue for an EV owner in providing frequency control in Denmark. User constraints are considered while evaluating the daily duration the EV is plugged into the network ready to support the system frequency. Performing unidirectional frequency control with Electric Vehicles (EVs) requires little hardware implementation in the household but has the limit that the service only can be performed until the battery is fully charged. Bidirectional V2G frequency control requires an external charger but also enables the EV to perform services at higher powers, during the entire period the EV is parked. The yearly revenue is in both cases calculated using some assumptions that are then verified in 2 experiments. Both EVs are discharged with the same amount of energy, such that their initial State of Charge (SOC) is set to the same level.

A method for remote control of EV charging by modifying IEC61851 compliant EVSE based PWM signal

The Electric Vehicle (EV) has properties that can not only load but can elevate its value as a resource to the power system. An EV represents a high-power, fast-responding flexible demand unit, with an attached energy storage (battery) and the potential for bi-directional capabilities (V2G). These properties can be used in a number of power and energy services, which can support power system operation while lowering the cost of EV ownership. Such services depend on the support from the communications technologies and standards that connect controllers and logic in the EVs with those in the charging infrastructure- and back-end systems. To date, there is still no widely adopted standard that supports EV grid services, such as smart charging. This work proposes a solution that would allow any combination of charging spot and EV - individually lacking the logic, communication and controllability required for smart charging - to gain this ability by simply adhering to the widely supported IEC61851 standard. This paper describes the solution, demonstrates the implementation and discusses the potential it has for unlocking EV power- and energy services.