A linear hybrid active disturbance rejection controller design to extenuate powerline bushfires in resonant grounded distribution power systems

This paper proposes a robust linear hybrid controller by combining the active disturbance rejection and proportional–integral controllers (ADRC+PI) for inverter-based arc suppression coils (ASCs) in resonant grounded distribution power systems (RGDPSs). Resonant grounding techniques are used in real power distribution networks for reducing the fault current in order to reduce the severity of powerline bushfires in the presence of single line-to-ground (SLG) faults. The severity of bushfire hazards due to these SLG faults depends on environmental conditions (e.g., wet or dry grounds) that define the behavior of the system. With respect to these conditions, the fault resistance will be lower for wet grounds for which the system model comprises one dominant pole while dry grounds force the system to have one dominant zero with two dominant poles. By considering the circumstances of such groundings, the behavior of power distribution systems changes when there are SLG faults. This paper investigates a detailed analysis in frequency- and time-domains to design a robust arc mitigator based on the hybrid ADRC+PI controller. Furthermore, the robustness of the proposed hybrid controller against the input disturbances is explored in terms of transient and steady-state stability analysis and the results are compared with the ADRC and PI controllers. In addition, the performance of the proposed hybrid ADRC+PI controller is justified by utilizing virtual- and real-time implementations in a digital signal processor (DSP) through MATLAB/SIMULINK platform on a 22 kV (line-to-line) RGDPS under distinctive grounding conditions

A novel coordinated optimization strategy for high utilization of renewable energy sources and reduction of coal costs and emissions in hybrid hydro-thermal-wind power systems

In multi-source-based energy systems, the ultimate target of optimal operation of the generation units is to create an efficient power system with cleaner production. In this paper, a novel coordinated operation strategy optimizing the commitment of hydro, thermal and wind generation units is proposed. The strategy consists of two hierarchical optimization goals. In the primary goal, utilization of wind and hydro energy units is optimized, and the objective functions involve maximizing hydro energy utilization and minimizing wind curtailment. In the secondary goal, coal costs and carbon emissions are minimized after meeting the utilization goal. The overall execution of the strategy is governed by three power production decisions including peak-load shaving, valley-load filling and generation. The first two decisions suppress the fluctuation in wind power while the generation decision makes full use of the hydro units to replace the working thermal units. The presented operation strategy is applied to an improved IEEE 118-node power system. The optimization ensures the highest utilization of wind energy while coping with the day-ahead wind power forecasting error. Moreover, a particle swarm optimization method is applied to optimize the coal costs and carbon emissions. The presented results demonstrate the capability of the proposed strategy to configure the operation of the multi-source-based energy system with high efficiency and low emissions. Finally, several recommendations to amend the existing management of multi-source-based energy systems are presented

A nonlinear model predictive controller design for residual current compensation inverters in rapid earth fault current limiters to mitigate powerline bushfires

This paper presents a nonlinear model predictive control scheme for residual current compensation inverters in rapid earth fault current limiters to inject appropriate current to the neutral so that the fault current is compensated in distribution networks. The proposed nonlinear model predictive controller is designed to limit the fault current within a level that powerline bushfires do not ignite due to single line-to-ground faults on power distribution systems in bushfire prone areas. The nonlinear model predictive controller is designed for a T-type residual current compensation inverter in rapid earth fault current limiters based on its dynamical model where the control objective is to inject current for compensating the fault current. The control law for the residual current compensation inverter is obtained by solving an optimal control problem while using the concept of the receding horizon control scheme. The performance of the controller is evaluated through standard software-based computer and processor-in-loop simulations where results are benchmarked against backstepping and sliding mode controllers in terms of compensating both faulty phase voltage and fault current

A discrete sliding mode control scheme for arc suppression devices in resonant grounded power distribution systems to mitigate powerline bushfires

In this paper, a discrete sliding mode control scheme is developed for the residual current compensator (RCC) inverter in a arc suppression coil (ASC) which is used for eliminating the fault current in resonant grounded power distribution networks to eliminate the impacts of powerline bushfires. The proposed discrete sliding mode controller (D-SMC) is designed based on the dynamical model of the ASC where the model is first represented in the dq-frame and then discretized. The D-SMC ensures the injection of the desired current through the RCC inverter so that the current flowing through the neutral reduces to zero which in turn reduces the phase-to-ground voltage of the faulty phase and hence, mitigates the adverse effects of powerline bushfires. A discrete sliding surface is selected to determine the switching control inputs for the RCC inverter and the stability of the proposed D-SMC is also analyzed to ensure the injection of the desired current to the neutral point under any operating conditions while satisfying operational standards. The effectiveness of the proposed D-SMC is evaluated through simulation results in terms of minimizing the fault current through the injection of the current to the neutral point and comparisons are made with existing proportional integral (PI) controller through simulations as well as other control strategies

A nonlinear double-integral sliding mode controller design for hybrid energy storage systems and solar photovoltaic units to enhance the power management in DC microgrids

In this paper, a nonlinear decentralized double-integral sliding mode controller (DI-SMC) is designed along with an energy management system (EMS) for the DC microgrid (DCMG). This DCMG includes having a hybrid energy storage system (HESS) that incorporates a battery energy storage system (BESS) and supercapacitor energy storage system (SCESS) while the load demand is met through the power generated from solar photovoltaic (SPV) units. First, dynamical models of each subsystem of DCMGs such as the SPV system, BESS, and SCESS are developed to capture highly nonlinear behaviors of DCMGs under various operating conditions. The proposed nonlinear DI-SMC is then designed for each power unit in DCMGs to ensure the desired voltage level at the common DC-bus and appropriate power dispatch of different components to fulfill the load requirement of the DCMG. On the other hand, an energy management system (EMS) is designed to determine the set point for the controller with an aim of ensuring the power balance within DCMGs under various operating conditions where the overall stability is assessed using the Lyapunov theory. Simulation studies along with the processor-in-loop validation, including a comparative study with a proportional-integral (PI) controller, verify the applicability and effectiveness of the EMS-based DI-SMC under different operating conditions of the DCMG

Cloud Energy Storage Based Embedded Battery Technology Architecture for Residential Users Cost Minimization

This paper presents a cloud energy storage (CES) architecture for reducing energy costs for residential microgrid users. The former of this article concentrates on identifying an appropriate battery technology from various battery technologies with the aid of a simulation study. The later part addresses the economic feasibility of the storage architecture with three different scenarios namely grid connected energy storage, distributed energy storage (DES) and CES. The performance of the proposed architecture has been evaluated by considering five residential users with suitable battery technology identified from the former part of the study. For the purpose of the analysis, PV and load profiles including seasonal effects and grid price were taken from IIT Mumbai, India and IEX portal, respectively. In addition, this article also examines the impact of increased number of users with CES. The value of this study is that the proposed CES architecture is capable of reducing the cost of electricity experienced by the user by 11.37% as compared to DES. With this, CES operator's revenue can be increased by 6.70% in summer and 16.97% in winter in the case of fixed number of users. Finally, based on the analysis and simulation results, this paper recommends CES with Li-ion battery technology for residential application

Harmonics propagation and interaction evaluation in small-scale wind farms and hydroelectric generating systems

The harmonics exacerbated by the integration of distributed energy such as wind power has been extensively studied. However, the interaction and propagation mechanism between harmonic sources in the hydro-wind complementary generation system are still not clear. To tackle this challenge, the presented study establishes the hydro-wind complementary generation system model and explores the harmonics propagation and interaction in all components. Then three operation mode of complementary system (scenario 1: stand-alone Hydroelectric Generating System, scenario 2: stand-alone Wind Farm (WF) and scenario 3: complementary generation system) are selected. The results demonstrate that the integration of HGS diminishes the harmonic at DFIG side but at the grid side. In complementary generation system, the THDu rises but the corresponding THDi declines due to the regulation of power grid. Furthermore, the odd harmonics interactions analysis reveal that the doubly-fed induction generator's (DFIG) side and the stator's side are the two high-risk sources in the complementary generation process. The presented results provide a basis for power quality evaluation of hydro-wind complementary generation system