This paper proposes a distributed finite-time secondary controller to achieve average voltage regulation and proportionate current sharing within a finite settling time for autonomous network of dc ...microgrids. It is employed by using a distributed finite-time control approach which maintains average voltage regulation of the system facilitating proportionate current sharing simultaneously by virtue of dynamic consensus between its neighbors. The proposed scheme ensures an improved performance over the conventional distributed secondary methods by reducing overshoots and chattering which is significant for critical operation of the loads. The proposed control strategy is simulated in MATLAB/Simulink environment to test link-failure resiliency, plug and play capability, and controller performance under communication delays within a tolerable upper bound on delay determined using time-delay analysis. Moreover the effect of variable time delays in different transmission medium is also simulated to test the practicality of the approach. This strategy is further tested on a 500-W FPGA-based experimental prototype to validate the control approach under different scenarios.
The use of artificial intelligence (AI) is increasing in various sectors of photovoltaic (PV) systems, due to the increasing computational power, tools and data generation. The currently employed ...methods for various functions of the solar PV industry related to design, forecasting, control, and maintenance have been found to deliver relatively inaccurate results. Further, the use of AI to perform these tasks achieved a higher degree of accuracy and precision and is now a highly interesting topic. In this context, this paper aims to investigate how AI techniques impact the PV value chain. The investigation consists of mapping the currently available AI technologies, identifying possible future uses of AI, and also quantifying their advantages and disadvantages in regard to the conventional mechanisms.
This article addresses the disturbance rejection problem of a nonminimum phase dc-dc boost converter operating in the continuous conduction mode (CCM) using a novel robust ...proportional-integral-derivative (PID) controller design method. The proposed idea is to design the controller using the equivalent feedforward formulation of the modified direct synthesis (MDS) approach. The advantages of the proposed MDS design are: 1) systematic incorporation of disturbance dynamics and the converter dynamics explicitly in the controller design to reduce the complex tuning effort of the controller parameters; 2) allowing the converter to operate close to the performance limit set by the zero in the right half-plane (RHP); 3) the closed-loop performance specifications can be incorporated into the desired loop response using only single tuning parameter based on Bode's gain crossover frequency inequality; 4) attenuates the loop gain to improve the disturbance rejection; and 5) realization of controller requires only output voltage as a feedback signal. The strength of the proposed MDS method is compared with the internal model control (IMC) method in both simulations and experiments. Based on these responses, the proposed PID ensures robust performance to the model-plant mismatch and allows the output voltage to quickly recover back to the operating voltage in the presence of external disturbances with less inductor current.
The integration of variable distributed generations (DGs) and loads in microgrids (MGs) has made the reliance on communication systems inevitable for information exchange in both control and ...protection architectures to enhance the overall system reliability, resiliency and sustainability. This communication backbone in turn also exposes MGs to potential malicious cyber attacks. To study these vulnerabilities and impacts of various cyber attacks, testbeds play a crucial role in managing their complexity. This research work presents a detailed study of the development of a real-time co-simulation testbed for inverter-based MGs. It consists of a OP5700 real-time simulator, which is used to emulate both the physical and cyber layer of an AC MG in real time through HYPERSIM software; and SEL-3530 Real-Time Automation Controller (RTAC) hardware configured with ACSELERATOR RTAC SEL-5033 software. A human–machine interface (HMI) is used for local/remote monitoring and control. The creation and management of HMI is carried out in ACSELERATOR Diagram Builder SEL-5035 software. Furthermore, communication protocols such as Modbus, sampled measured values (SMVs), generic object-oriented substation event (GOOSE) and distributed network protocol 3 (DNP3) on an Ethernet-based interface were established, which map the interaction among the corresponding nodes of cyber-physical layers and also synchronizes data transmission between the systems. The testbed not only provides a real-time co-simulation environment for the validation of the control and protection algorithms but also extends to the verification of various detection and mitigation algorithms. Moreover, an attack scenario is also presented to demonstrate the ability of the testbed. Finally, challenges and future research directions are recognized and discussed.
This paper proposes an adaptive event-triggered communication-assisted distributed secondary cooperative control strategy using a parameter projection law-based estimate of states to reduce ...communication burden. It overcomes the drawbacks of operating in an open loop manner between two triggering time instants in traditional zero-order hold-based event triggering schemes using a full state feedback control strategy to update the control input simultaneously. Moreover, real-time precision of information and model uncertainties is well dealt owing to the adaptive mechanism via an event-triggering condition designed using the Lyapunov technique to ensure the stability of the system. This strategy is used in tandem to achieve global average voltage regulation and proportionate load sharing in dc microgrids for various disturbances without sacrificing system performance. The proposed control strategy is simulated in MATLAB/Simulink environment and tested on a 500-W FPGA-based experimental prototype to validate the control approach under different scenarios.
This paper develops a robust chance-constrained model for handling the uncertainties of generation and consumption in multi-carrier energy hubs. The proposed model incorporates corresponding loading ...factors for each type of electrical, heating, and cooling loads. This is done to assess the maximum loadability of the whole system. In this respect, the chance-constrained approach is implemented for the feasibility assessment of the operation problem with uncertainties. The uncertainties which are assumed here include the forecast errors of electrical, heating, and cooling load demands, and the volatile solar power generation. The overall problem formulation is developed in the mixed-integer linear programming (MILP) framework. The standard chance-constrained approach is converted to a deterministic optimization model by utilizing the Big M method. The main objective of the proposed model is to maximize the loadability index with uncertainties while addressing the permissible risk index of the decision-maker. The studied energy hub comprises electrical, heating, and cooling loads, and the energy flow technique is adopted in this paper to model the load balance equations. The simulation results are presented for different scenarios while addressing features of the proposed model for the summer and winter seasons. Furthermore, the developed model is evaluated for different scenarios and a comparison is made with the information-gap decision theory (IGDT) method.
Although power electronic converters have been the key enablers for the the integration of renewable generation, heterogeneous controllers and lower inertia increase the complexity of microgrids, ...more likely to cause instability. Hence, it is significant to study the stability of microgrids using prospective modeling tools such as, bode plots, Nyquist plots, eigenvalue loci, etc. The modeling of microgrids is an important step of stability analysis, where state-space-based and impedance-based modeling are the two commonly used stability evaluation approaches in microgrids. Miscellaneous modeling methods have respective pros and cons, which have been investigated in the existing literatures to some extent. However, it is still critical to quantify the modeling techniques so as to formalize the stability validation in an intuitive way, which is not addressed in existing literatures. Therefore, in this paper, modeling methods for stability validation are mapped based on an order-indicated complexity, and a quantitative framework for the mapping is provided. The proposed framework can be instructive when modeling microgrid systems with different sizes, topologies or control strategies, etc., and it turns out to be well applicable as demonstrated by exemplified simulations and experimental tests.
This paper reviews and discusses the state of the art of integrated switched-capacitor and integrated inductive power converters and provides a perspective on progress towards the realization of ...efficient and fully integrated DC–DC power conversion. A comparative assessment has been presented to review the salient features in the utilization of transistor technology between the switched-capacitor and switched inductor converter-based approaches. First, applications that drive the need for integrated switching power converters are introduced, and further implementation issues to be addressed also are discussed. Second, different control and modulation strategies applied to integrated switched-capacitor (voltage conversion ratio control, duty cycle control, switching frequency modulation, Ron modulation, and series low drop out) and inductive converters (pulse width modulation and pulse frequency modulation) are then discussed. Finally, a complete set of integrated power converters are related in terms of their conditions and operation metrics, thereby allowing a categorization to provide the suitability of converter technologies.
In this paper, the model predictive control (MPC) strategy is utilized in smart homes to handle the optimal operation of controllable electrical loads of residential end-users. In the proposed model, ...active consumers reduce their daily electricity bills by installing photovoltaic (PV) panels and battery electrical energy storage (BEES) units. The optimal control strategy will be determined by the home energy management system (HEMS), benefiting from the meteorological and electricity market data stream during the operation horizon. In this case, the optimal scheduling of home appliances is managed using the shrinking horizon MPC (SH-MPC) and the main objective is to minimize the electricity cost. To this end, the HEMS is augmented by the SH-MPC, while maintaining the desired operation time slots of controllable loads for each day. The HEMS is cast as a standard mixed-integer linear programming (MILP) model that is incorporated into the SH-MPC framework. The functionality of the proposed method is investigated under different scenarios applied to a benchmark system while both time-of-use (TOU) and real-time pricing (RTP) mechanisms have been adopted in this study. The problem is solved using six case studies. In this regard, the impact of the TOU tariff was assessed in Scenarios 1-3 while Scenarios 4-6 evaluate the problem with the RTP mechanism. By adopting the TOU tariff and without any load shifting program, the cost is <inline-formula> <tex-math notation="LaTeX">\ </tex-math></inline-formula>1.2274 while by using the load shifting program without the PV and BEES system, the cost would reduce to <inline-formula> <tex-math notation="LaTeX">\ </tex-math></inline-formula>0.8709. Furthermore, by using the SH-MPC model, PV system and the BEES system, the cost would reduce to <inline-formula> <tex-math notation="LaTeX">\ </tex-math></inline-formula>-0.282713 with the TOU tariff. This issue shows that the prosumer would be able to make a profit. By adopting the RTP tariff and without any load shifting program, the cost would be <inline-formula> <tex-math notation="LaTeX">\ </tex-math></inline-formula>1.22093 without any PV and BEES systems. By using the SH-MPC model, the cost would reduce to <inline-formula> <tex-math notation="LaTeX">\ </tex-math></inline-formula>1.08383. Besides, by adopting the SH-MPC, and the PV and BEES systems, the cost would reduce to <inline-formula> <tex-math notation="LaTeX">\ </tex-math></inline-formula>0.05251 with the RTP tariff, showing the significant role of load shifting programs, local power generation, and storage systems.
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