Frequency-constrained energy and reserve scheduling in wind incorporated low-inertia power systems considering vanadium flow redox batteries

This paper proposes a novel energy and reserve scheduling model for power systems with high penetration of wind turbines (WTs). The objective of the proposed model is to minimize the total operation cost of the system while static and dynamic security is guaranteed by preserving the frequency nadir, RoCoF, and quasi-steady-state frequency in the predefined range. Likewise, a supervisory, control, and data acquisition (SCADA) system is developed which allows Vanadium Redox Flow Batteries (VRFBs) to continuously communicate and participate in the primary frequency response. To cope with the uncertainties, adaptive information gap decision theory is used that ensures a target operating cost for the risk-averse operator of the power system. The proposed scheduling model is applied on a modified IEEE 39 bus test system to verify the impacts of the fast reserve provided by the VRFBs in the dynamic frequency security enhancement of the power system with high penetration of WTs

Overarching Preventive Sympathetic Tripping Approach in Active Distribution Networks Without Telecommunication Platforms and Additional Protective Devices

Nowadays, distributed generation (DG) has made it possible to generate electricity close to the consumption site, resulting in improved efficiency, less environmental pollution, and higher economic profit. These advantages have led to increased penetration of DGs in the distribution system. Protective devices in a distribution system are set by considering the main substation as the only source for feeding short circuit current. However, with the increased influence of DGs as the second main source of short circuit current in distribution systems the short circuit level changes, which leads to false tripping of protective devices, including overcurrent relays. A sympathetic trip, occurring due to a fault in the adjacent feeder, is one of the most serious challenges. This paper analyzes the sympathetic trip in the presence of synchronous based DGs. The equations related to the participation of DGs and upstream network in feeding the short circuit current are obtained. The effect of different parameters on the probability of occurrence of a sympathetic trip is also investigated. Moreover, a novel fast solution is presented for overcoming the sympathetic trip of synchronous based DGs. The proposed method is introduced using the positive-sequence currents of the DGs and main substation. The sympathetic trip is predicted by adopting this prediction index and its occurrence is avoided. The proposed methodology is independent of telecommunication platforms and additional protective devices and can be applied to various short circuits. The method is tested on a network by simulating in DIgSILENT PowerFactory software. Simulation results show the effectiveness of the proposed methodology in predicting and preventing sympathetic trips

Optimal Design Parameter Determination for Brushless Doubly Fed Induction Machines

Brushless doubly fed induction machines (BDFIM) have prominent features for variable speed applications. The design and performance analysis of the machine is however complex compared to the conventional induction machines due to its special magnetic fields generated from two stator winding with different pole numbers and frequencies. In this paper, the effective parameters in BDFIM design and their limitations are investigated. In relation with the design objectives, control variables are identified, and an optimal prototype machine design is proposed. The results from experimental tests and finite element simulations of a 3 kW prototype BDFIM are presented to assess the effectiveness of the proposed parameters determination method

Predication of steady-state thermal characteristics of a resistance spot welding transformer in battery manufacturing application

This paper introduces a novel finite-element-method-based model designed to analyze the electromagnetic–thermal dynamics of resistance spot welding (RSW) transformers used in battery manufacturing. The RSW process, inherently multiphysics and sensitive to temperature fluctuations, involves phase changes within the metal materials. This complexity, combined with frequent electrode connections and disconnections during welding (variable structure), renders traditional steady-state analysis methods inadequate for accurately capturing temperature and electromagnetic parameters under thermal steady-state conditions, and the effect of changing power electronics parameters (frequency, number of cycles, and firing angle) on continuous operation is also unpredictable. The article proposes a method capable of determining temperature trends during electrode opening (rest period). It simplifies the temperature characteristics and material properties of the welding spot. These variations are equated and simplified as a constant temperature and an equivalent material, respectively. The proposed model, rooted in finite-element analysis and experimentally validated, enables a bidirectional electromagnetic–thermal simulation through steady-state thermal analysis. This simulation generates results for temperature and electromagnetic values during steady-state operation, demonstrating close agreement with experimental results. Consequently, the developed model showcases its capability in predicting the impacts and sensitivities of various factors, such as voltage cycle number, firing angle, and rest period duration within the RSW process

Frequency‐constrained energy and reserve scheduling in wind incorporated low‐inertia power systems considering vanadium flow redox batteries

This paper proposes a novel energy and reserve scheduling model for power systems with high penetration of wind turbines (WTs). The objective of the proposed model is to minimize the total operation cost of the system while static and dynamic security is guaranteed by preserving the frequency nadir, RoCoF, and quasi-steady-state frequency in the predefined range. Likewise, a supervisory, control, and data acquisition (SCADA) system is developed which allows Vanadium Redox Flow Batteries (VRFBs) to continuously communicate and participate in the primary frequency response. To cope with the uncertainties, adaptive information gap decision theory is used that ensures a target operating cost for the risk-averse operator of the power system. The proposed scheduling model is applied on a modified IEEE 39 bus test system to verify the impacts of the fast reserve provided by the VRFBs in the dynamic frequency security enhancement of the power system with high penetration of WTs.CC BY 4.0Funding: none.</p