Single-ended fault location accuracy is adversely influenced by integration of the inverter based renewable resources (IBRs). In this paper, we cover a more generic examination of performance of single-ended fault locator for lines connected with IBRs. This analysis is used for understanding the causes of high fault location error for lines with IBRs. This information can be used for designing accurate single-ended fault locator for IBR connected networks. The paper also presents a mitigation approach which has potential improvement in fault location accuracy by using remote terminal current. The remote current is readily available, as most of the IBR connected lines are employed by differential relays as main protection. The proposed mitigation approach can be implemented in the existing line differential protection IEDs (Intelligent Electronic Devices). The approach is demonstrated using EMTDC simulation of a 220-kV, 200km transmission line connected with IBRs. Validation with field data confirms the accuarcy of proposed mitigation approach.
In the past few years, there have been some serious concerns regarding climate change, and its adverse effects can be observed in today’s era. Due to this, the use of renewable sources of energy is increasing exponentially. Although renewable energy sources come with significant advantages, the intermittent nature of the supply causes fluctuation in the power supply when connected to the distribution system. High PV penetration during peak generation causes over-voltage problems in the system and may result in outages of the line due to tripping of protection circuits. In this research, controlled use of Battery Energy Storage Systems (BESS) is proposed to solve the problem of both over-and under-voltage issues due to the intermittent nature of the supply of renewable sources. The coordinated control strategy proposed in this research is a combination of droop control, Weighted Consensus Control (WCC), and Dynamic Consensus Control (DCC) algorithm. The droop control method determines the power shared between BESS and the network, the WCC algorithm is used to determine the BESS participation according to their installed capacity. Finally, the DCC algorithm is used to modify the BESS participation according to the state of charge (SoC) so that the batteries do not saturate or deplete early. Finally, the control strategy is tested on real-time data, and simulation results are considered to check this method’s efficiency.
This paper presents coordinated control scheme of electric vehicle charging stations (EVCSs) in smart transformer (ST) based microgrid. The microgrid is connected to the main grid through ST. Here, ST low voltage (LV) ac side converter is operating on the droop-control method. Battery energy storage system (BESS) and photovoltaic (PV) are connected to LVac line through droop-controlled converters. Two levels of hierarchical control structure have been implemented here: primary control and secondary control. EVCS connected at the load bus is used as the controllable unit in microgrid, which can regulate the voltage and frequency at load bus. Moreover, EVCS supports the microgrid with reactive power by varying their charging power. The secondary control at the microgrid centralised controller (MGCC) sends compensation signals to all the control units of droop-controlled converters and EVCS using the low bandwidth communication link. Simulation results show that the microgrid provides power at nominal voltage and frequency using secondary compensation signals. Along with controllable charging, EV supports reactive power as the voltage deviation at load bus goes beyond minimum threshold limit. The results are verified using the MATLAB/Simulink software.
An ever-growing demand of information technology (IT) services, cloud servers and digitalization has led to an exponential increase in the demand for digital storage, power demand, and energy consumption in data centres. In this paper, a smart transformer (ST) enabled triple-active bridge (TAB) converter for modern data centres is proposed. The smart transformer delivers power from medium voltage (MV) utility grid to low voltage (LV) ac load. The triple-active bridge (TAB) converter plays a pivotal role in supplying power from LVdc bus down to various lowlevel dc voltages required by the data centres. This ST enabled TAB converter offers several features such as reduced conversion stages, high frequency power conversion, connection of alternate power sources, higher efficiency, power density and reliability. The proposed system provides both ac and dc powers required by the data centre loads, and this can also be operated in UPS mode to ensure the continuity of power supply. The simulation is done in PSCAD/EMTDC software and the operation of the proposed system is verified.
Distributed control of microgrids are becoming popular due to their scalability and reliability. Most distributed controllers designed for the microgrids are in the continuous time domain and subsequently implemented on digital controllers, which work in discrete time. Due to sampling time concerns, continuous time-domain control gains may not function well for digital controllers. This paper presents a discrete-time distributed secondary control to achieve frequency restoration and average voltage control in an ac microgrid. The proposed distributed frequency control ensures frequency restoration while maintaining proportionate active power sharing. The distributed voltage and reactive power control guarantee the average microgrid voltage is restored to the reference value and achieves proportionate reactive power sharing. Simulation in MATLAB/Simulink to verify the effectiveness of the proposed control scheme. The proposed controller is implemented on a digital FPGA controller and tested the experimental setup with different loads, and the results are presented.
