Effect of communication infrastructure delays for EV/ESS aggregation on frequency regulation and its market

Abstract

In this dissertation, we investigate the effect of a time-varying delay problem and an uncertain capacity submission problem in EV aggregators on frequency regulation (FR) performance and payments. First, we present a communication infrastructure for EV aggregators and analyze the delay performance of FR service in EV aggregators' domain. For reliable FR under the identified delayed performance of EV aggregators, we investigate the stability of FR. To determine whether the power system is stable under the given information on time-varying delays, we propose stability criteria of linear systems with single and multiple time-varying delays and analyze stability regions of FR when EV aggregators with single and multiple time-varying delays participate in the FR service using the proposed criteria. Next, we investigate whether the existing FR payment rules encourage EV aggregators to reduce the delays in order to improve the FR performance and stability. We analyze the effect of delays in the EV aggregators' domain on the conventional regulation payments. To this end, as a framework for evaluating the payments, we enhance the conventional load frequency control model by including multiple EV aggregators with varying delays. Through simulations, we show that the conventional mileage payments cannot motivate EV aggregators to reduce the delay in order to improve regulation performance. To solve the problem, we propose a new mileage payment to reduce the delay. We show that the proposed payment works as an encouragement mechanism for delay reduction. Last, we analyze how the uncertain capacity submission of EV aggregators affects the conventional regulation payments. Through simulations, we show that the conventional FR settlements fail to induce EV aggregators to estimate the accurate achievable power capacity. To solve this problem, we propose to enhance the accuracy of performance in settlement. We show that the proposed scheme can restrict the surplus contracted capacity.