The high penetration of renewable energy generation (REG) systems influences the dynamics power systems. Accurate transient simulations and dynamic models are indispensable for research on behavior REG A large-scale system consisting numerous grid-connected inverters consumes a large amount computation time, so aggregated model is needed efficient simulation. established by coherent equivalence fits detailed well, thus it widely used in aggregation Presently, key challenge application...

Source-side virtual synchronous machines (VSGs) and load-side VSMs (LVSM) are gradually utilized together in the microgrid to provide inertia damping. However, instability occurs islanded system due interaction dynamics between VSG LVSM, which has been investigated this article. At first, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -frame impedance models of LVSM established compared. It is revealed that d-d channel behaves...

In islanded microgrids with complex feeder networks, distributed generation units (DGs) and loads can be freely connected to any node, leading changes in the impedance between nodes microgrid structure. However, traditional harmonic sharing control methods encounter difficulties topologies. Additionally, existing techniques essentially require constructing additional virtual impedance, possibly resulting conflict voltage quality effectiveness. To address this issue, paper proposes an...

For the distributed generation units (DGs) using virtual synchronous generator (VSG) control algorithm connected to islanded microgrid with high penetration of nonlinear load, there is always a trade-off between harmonics sharing accuracy and voltage quality when conventional methods. To address this issue, an impedance-based adaptively reshaping method proposed in paper, which based on harmonic current feedforward compensation impedance factor adaptive control, assigning variable for each...

Virtual synchronous machine (VSM) based high voltage dc systems enhance the inertia of power system. However, dynamic interactions between VSM-based rectifier station, inverter and grid could induce system oscillation, which has been investigated in this article. At first, hybrid ac–dc impedance models VSMs considering coupling ac dynamics are established. Then, relationships impedance, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i>...

Impedance-based approachis generally studied for stability analysis of the power electronic converter-based system. Considering multiple-frequency coupling effects, in this article, we establish harmonic transfer function (HTF) based <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">αβ</i> -frame impedance models droop inverters islanded microgrid with unbalanced loads. Therein, HTF-based -impedance modeling methods loads, as well parallel, are...

Converter-control-based generators exhibit different dynamic characteristics compared with traditional synchronous generators, and thus affect the oscillation modes small-signal stability of power systems in a manner. Simplified representation great number grid-connected inverters is indispensable for efficient accurate analysis integrated large-scale renewable energy generation. This paper proposes novel aggregation modeling method using coherency-based equivalence, validates applicability...

In this article, we present an adaptive broadband thyristor-controlled impedance matching network (TCIMN) for increasing power utilization from a amplifier to the loads. Different conventional passive methods, proposed one can achieve load under wide frequency range of amplifiers. First, operation principle TCIMN is introduced mathematically. Based on that, parameter design method based required range. Moreover, operating and harmonic analyses are provided give firing angle ranges different...

This article proposes an adaptive broadband full-bridge converter impedance matching network (FCIMN) between a power amplifier and the giant magnetostrictive transducer (GMT). Compared with conventional passive methods, proposed one can realize load of amplifiers under wide frequency range. In this article, first, elementary principle operation FCIMN is introduced mathematically. After that, control method to achieve matching, including dynamic active calculation, reactive segmented...

The ac/ac modular multilevel converter (MMC) application in the electric railway poses new challenges to stability of system. impedance analysis method is an effective way assess MMC-based systems. Due internal dynamics MMC, there are steady-state harmonic components arm currents and capacitor voltages, these have a significant impact on dynamic characteristics MMCs. To accurately predict systems, this article proposes model MMC with consideration dominant harmonics. Simulation experimental...

Transient angle instability and fault overcurrent are two serious problems affecting the safe operation of virtual synchronous generator during grid faults. However, aspects mostly treated as independent in existing studies. In this article, taking both transient into consideration, a two-stage control collaboratively utilizing impedance (VI) switching PI is put forward. stage one, VI switched to boundary value determined by iteration algorithm avoid overcurrent. two, proportional loop or...

The rapid development of large scale power system and the implementation dispersed generation have led to increasing level fault current which may be over breakers' operating limit threatening safety system.

Interactions of identical inverters in weak grids have received wide attentions. However, a practical wind farm, parameters grid-side and lengths collecting lines are not completely the same. In this case, multi-inverter system is symmetric, thus interaction mechanism could be more complicated than that inverters. To investigate differently parameterized inverters, paper proposes clustering-based modeling method, which with classified as one group. The model allows for efficient stability...

Since the power supply is limited in ships, impedance matching network essential for a high-power underwater electroacoustic transduction system. However, existing networks can barely achieve full under wide frequency change range. This paper proposes shunt active (SAIMN) to adaptive broadband (up 400Hz) increasing utilization from amplifier transducer. Firstly, load characteristic and operation principle of SAIMN are introduced mathematically. Secondly, parameter design method provided...

Reverberation is the main background interference in active sonar and seriously interferes with extraction of target echo. Active systems can use short-pulse continuous wave (CW) signals to reduce reverberation intensity. However, as pulse width CW decreases, envelope exhibits a high-frequency oscillating phenomenon. often uses cell average constant false alarm ratio (CA-CFAR) method process reverberation, which steadily decays transmission distance. oscillation deteriorates performance...

The application of fault current limiter is an effective method to limit current. saturated-core (SFCL) one the promising devices. However, its commercialization limited by high demands for ferromagnetic material and dc source generating magneto motive force. This paper proposes a novel three-phase compact SFCL (CSFCL) in which common core permanent magnet are used solve mentioned challenges. can significantly reduce amount required material. basic operating principle CSFCL introduced based...

Simplified weak grid models are widely used to emulate the nonideal power for design and stability analysis of grid-connected inverters. However, dynamic behavior a real with multiple inverters is complex. In this article, an emulation method proposed multi-inverter integrated grids using interaction-preserved aggregation model associated impedance. First, interaction among in analyzed state-space participation analysis. Then, two-inverter large-scale system. This can preserve impact...

This article proposes a power selective control with fault tolerance of multifunctional inverter for active injection and quality compensation. The is widely researched, because the capacity can be fully used to realize multiple functions. However, legs may have open-circuit during operation, affecting realization functions even causing secondary fault. Following early stage detections, applied inverters, in some cases, prevent unexpected shutdowns. enables reconstructed another steady state...