This paper presents the design and realization of a digital PV simulator with a Push-Pull Forward (PPF) circuit based on the principle of modular hardware and configurable software. A PPF circuit is chosen as the main circuit to restrain the magnetic biasing of the core for a DC-DC converter and to reduce the spike of the turn-off voltage across every switch. Control and I/O interface based on a personal computer (PC) and multifunction data acquisition card, can conveniently achieve the data acquisition and configuration of the control algorithm and interface due to the abundant software resources of computers. In addition, the control program developed in Matlab/Simulink can conveniently construct and adjust both the models and parameters. It can also run in real-time under the external mode of Simulink by loading the modules of the Real-Time Windows Target. The mathematic models of the Push-Pull Forward circuit and the digital PV simulator are established in this paper by the state-space averaging method. The pole-zero cancellation technique is employed and then its controller parameters are systematically designed based on the performance analysis of the root loci of the closed current loop with k i and R L as variables. A fuzzy PI controller based on the Takagi-Sugeno fuzzy model is applied to regulate the controller parameters self-adaptively according to the change of R L and the operating point of the PV simulator to match the controller parameters with R L . The stationary and dynamic performances of the PV simulator are tested by experiments, and the experimental results show that the PV simulator has the merits of a wide effective working range, high steady-state accuracy and good dynamic performances.
This paper investigates the use of a static synchronous compensator (STATCOM) to mitigate the voltage fluctuations and improve fault ride-through capability of wind farm with fixed speed induction generators. In order to assure STATCOM of running safely and reliably in both normal and faulty conditions, a novel control strategy which combines negative-sequence voltage feed-forward control with conventional vector control is proposed to make the negative sequence current of STATCOM zero and effectively suppress STATCOM overcurrent. The positive-sequence and negative-sequence components of the voltage at point of common coupling (PCC) are obtained quickly and accurately by the specially designed double synchronous reference frame phase locked loop (DSRF PLL). The simulation results show that the STATCOM not only significantly improves the power quality, but also enhances fault ride-through capability of wind farm. It is also concluded from the simulation results that the proposed control strategy can effectively suppress STATCOM overcurrent and guarantee that STATCOM can operate safely even in abnormal conditions. Index Terms--fault ride-through, overcurrent, phase locked loops, power quality, power system transient stability, static VAR compensators (STATCOM), voltage control, voltage unbalance, wind farm, wind power generation
The typical stand-alone microgrid (MG) composed of wind turbine (WT), photovoltaic (PV), diesel generator (DE), and battery energy storage (BES) is taken as the research object. Firstly, a multiobjective optimal capacity configuration model considering economic efficiency, reliability, and environmental protection is established. Secondly, in view of the complex characteristics of the optimization model, such as strong nonlinearity and multi-constrained conditions, combining the enumeration that can find the complete real Pareto solution set with the intelligent algorithm that has the characteristics of fast convergence, a search algorithm referencing adjacent points based on SPEA2 (SARAP) is proposed. The algorithm obtains the contour of the real Pareto optimal solution set by SPEA2, and then repeatedly extracts the adjacent points that satisfy certain conditions from the solution set solved by SPEA2. A small search space based on the adjacent points is constructed, and an omnidirectional search in this space to achieve the complete real Pareto optimal solution set is performed. The algorithm performance analysis of both computational complexity and convergence shows that the operation speed of SARAP is approximately five times higher than that of the enumeration, and the obtained result is close to the complete real Pareto optimal solution set. Finally, the optimization calculation and typical daily production simulation are carried out according to the resource and load characteristics of a region, and the results further prove the rationality and validity of the proposed algorithm. INDEX TERMSMicrogrid, capacity configuration, multi-objective optimization, SPEA2, SARAP. NOMENCLATURE A. ABBREVIATIONS AEC Annual emissions of CO2 BES Battery energy storage DE Diesel generator DG Distributed generation EAC Equivalent annual cost LPSP Loss of power supply probability MG Microgrid PV Photovoltaic SP Search process referencing adjacent points WT Wind turbine B. INDICES i Index of DG t Time C. VARIABLES cf1,cf2 Coefficients of the fuel consumption parameters (L/kW) CEAC Equivalent annual cost (¥) CFuel Fuel cost (¥) CInit Annual initial investment (¥) COM Annual operation and maintenance cost (¥) COMFix Fixed operation and maintenance cost (¥)
This paper proposes a novel virtual inertia control (VIC) method based on a feedforward decoupling strategy to address the low inertia issue of power-converter-interfaced microgrids. The feedforward control scheme is employed to eliminate the coupling between active and reactive power caused by line impedance. The active power-voltage droop can be applied to the battery converter in the hybrid energy storage system (HESS). A novel VIC method is developed for the supercapacitor (SC) converter of HESS to increase the inertia of the microgrid. Detailed small-signal modeling of the SC converter with the proposed VIC was conducted, and the transfer function model was obtained. Parameter analysis of the virtual inertia and virtual damping was carried out with the pole-zero map method, and the step response characteristic of output voltage amplitude with power variation was analyzed in detail, deriving the parameter design principle. The simulation study verifies the effectiveness and validity of the proposed control strategy. The proposed feedforward decoupling method and VIC can be widely applied in microgrids to enhance inertia and improve their power quality.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.