Loading...
2 results
Search Results
Now showing 1 - 2 of 2
- Scheduling of battery energy storages in the joint energy and reserve markets based on the static frequency of power systemPublication . Khojasteh, Meysam; Faria, Pedro; Vale, ZitaBy using the battery energy storage (BES) as a fast, reliable, and controllable resource, the system operator can compensate for power mismatches via changing the generation and consumption in discharging and charging modes. However, BES could decrease the inertia of the grid and endanger the security of the system. Therefore, system operators require a scheduling model that takes into account both security and economic issues. This paper presents a linear model for the optimal scheduling of synchronous generators and BESs in the joint energy and reserve markets, based on the constraints of primary and secondary frequency services. In the proposed model, the technical limitations of synchronous generators and BESs, the frequency limitation of the grid, rate of change of frequency (RoCoF) of generators, and the RoCoF of the grid are considered as constraints of the optimization problem. Accordingly, the optimal scheduling of the resources is determined in a way that ensures the security criteria of the system are not violated after the contingency. The effectiveness of the proposed strategy is demonstrated by four case studies. Simulation results show that increasing the battery capacity by 4.68% of the total capacity of the system reduces the total frequency reserves, and total costs of the system by 13.21 and 2.96%, respectively. Consequently, system operators can reduce total operating costs and provide adequate security by deploying BESs.
- Optimal strategy of electricity and natural gas aggregators in the energy and balance marketsPublication . Khojasteh, Meysam; Faria, Pedro; Lezama, Fernando; Vale, ZitaThis paper presents a stochastic two-stage model for energy aggregators (EAs) in the energy and balancing markets to supply electricity and natural gas to end-users equipped with combined heat and power (CHP) units. The suggested model takes into account the battery energy storage (BES) as a self-generating unit of EA. The upper and lower subproblems determine the optimal energy supply strategy of EA and consumption of consumers, respectively. In the lower subproblem, the McCormick relaxation is used to linearize the cost function of the CHP unit. To solve the proposed model, the two-stage problem is transformed into a linear single-stage problem using the KKT conditions of the lower subproblem, the Big M method, and the strong duality theory. The performance and efficiency of the proposed model are evaluated using a case study and three scenarios. According to the simulation results, adding CHP units to the energy-scheduling problem of BES-owned aggregators increases the profit of EA by 5.96% and decreases the cost of consumers by 1.57%.