With increasing penetration of the renewable energy, grid-tied PWM inverters need to take corresponding responsibilities for security and stability future grid, behaving like conventional rotational synchronous generator (RSG). Therefore, recognizing inherent relationship intrinsic differences between RSGs is essential such target. By modeling typical electromechanical transient inverters, this paper first proves that are similar in physical mechanism equivalent mathematical model, concept...

Active power filters are conventionally utilized to compensate steady-state harmonic currents and reactive in the utility, yet their capabilities usually limited if elimination of undesirable effects associated with decaying dc components during transients is target, especially under weak grid condition. In this letter, active cancellation typical first-order dc-mode explored. To end, a real-time detection algorithm component first developed for generic single-phase distorted ac signal....

To reduce the frequency deviation and rate of change (RoCoF) in a low-inertia power system, some converters are required to provide response (FR) normally associated with and/or RoCoF, by droop/inertia/PD control. In this article, rapid compensation (RPC)-based FR strategy is developed optimize ability compensate grid imbalance power, fully exploiting converter idle capacity. end, first, mathematical proof demonstrated improved performance RPC terms suppression versus droop control, RoCoF...

Droop control, inertia and PD control are three typical frequency response (FR) strategies of grid-tied inverters interfaced renewable energy sources (RES) to restrain the power system indicators, i.e., deviation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta \omega $ </tex-math></inline-formula> ) rate change (RoCoF). Due highly limited inverter capacity, FR performance in systems with high RES...

Isolation of the fault dc lines during initial short period after is a major challenge in multi-terminal (MTDC) system based on voltage-source converter (VSC). Existing protection schemes are mainly designed numerical simulations, which lacks theoretical analysis. In this paper, high-frequency equivalent model VSC-based MTDC first proposed for current calculation. Based analysis, it validated that components flow line and then dramatically decay healthy line. Accordingly, novel detection...

It is of great significance for a voltage source converter (VSC)-based multiterminal dc (MTdc) grid to isolate the fault lines within several milliseconds after fault. Existing protection schemes and analysis methods are mainly based on numerical simulations, which lack theoretical analysis. In this paper, high-frequency (HF) equivalent model VSC-based MTdc that utilized initial current calculation first proposed. proposed model, parallel connected capacitors VSCs regarded as...

Inverter-based standalone power systems (ISPSs), with limited inertia/damping, are prone to significant changes in frequency indicators encompassing deviation and rate of change (RoCoF), which can easily exceed the pertinent relay thresholds cause outages. Limited by estimating disturbance system inertia/damping deficiency, existing controls cannot ensure stability. To overcome this issue, a trajectory planning (FTP) based strategy is developed article improve stability droop-controlled...

Grid forming (GFM) converter mimics the operational characteristics of synchronous generator, serves as a voltage source that provides and frequency support to power system. However, due its nature, current GFM is highly determined by external system, increasing risk overcurrent under large disturbances potential damage converter. The conventional reference limitation suffers from synchronization instability, which causes lose synchronization. To address this issue, paper proposes novel...

Conventional orthogonal signal-generation methods for single-phase grid suffer from long response time, approximation errors, and/or noise amplification. To remedy this problem, a novel algorithm, which is characterized by remarkable speed, high accuracy, immunity, and easy implementation, developed in paper. The algorithm can precisely calculate the signal within about 2.5 ms when amplitude/phase of changes suddenly, under premise not significantly increasing computational burden compared...

Bypassing the faulty power unit(s) of regenerative cascaded multilevel inverter (CMI) directly results in a series adverse influences. The existing solutions are not easy to implement and only effective for V-connected devices composed CMIs. To bypass units seamlessly, corresponding control strategies must guarantee: 1) constant equivalent switching frequency; 2) sampling 3) fundamental voltage amplitude. this end, generic fault-tolerant strategy, which adjusts carrier frequency...

Renewable energy based micro grids have great importance to deal with energy-intensive. In this paper, we build a microgrid consist of AC line and DC at first. A common has its own control strategy management system. With compatible system, those distributed generations storage units can mostly improve the grid's efficiency. During island mode, should make full use renewable self-sufficient. And during grid-connected economical method reduce cost paid for electricity. even under some certain...

This paper mainly focuses on how to provide frequency supports by the doubly fed induction generator (DFIG) during system disturbances. Two coordinated controls that enable DFIG-based wind turbines (WTs) are proposed in this paper. The first control scheme seeks render support via simultaneously utilizing energy from installed super-capacitor between back-to-back converter of DFIG, and WT rotational kinetic (KE). second one stabilizes firstly exerting then KE a unique cascading control. Both...

Offshore wind power is continuously developing for renewable energy generation. Generally, the overall planning work of offshore farms (OWFs) divided into farm layout optimization (WFLO) and collector system (WFCSO), which focus on turbines' (WT) micro-siting sea cables' network design, respectively. Traditionally, optimizations these two subproblems are isolated, lacks integral consideration their co-effect optimal solution. Moreover, practicability also remains at a low level, with key...

Fast and accurate acquisition of voltage components is the basic requirement for grid-tied inverters to realize various control under unbalanced grids. In view this situation, a delay sampling period filter, which rapidly separates each component by delaying two periods in dq frame, proposed article. noise interference, operation filter (DOPF) scale limit an acceptable range. The complete positive sequence (PSC) extraction method based on developed DOPF+ moving average (MAF) algorithm...

For physically understanding the dynamic response of photovoltaic (PV) integrated power system for electromechanical oscillations damping, firstly, this paper develops linear mathematical model a single machine infinite bus by PV grid-tied inverter under time scale. Then, based on electric torque analysis method, and functional route variable active control (P-control) reactive (Q-control) with angle or grid frequency feedback as input signal, key factors influence laws inertia, damping...

Amplitude-phase information of the voltage/current phasor, which is prerequisite for grid-tied converter control and protection, can change almost instantaneously in low-voltage distribution systems with small X/R ratios. However, equivalent impedances high-voltage power are usually inductive (with large ratios), flow pertinent grids generates decaying dc (DDC) components amplitude long duration during disturbances. Therefore, ratios DDC must be fully considered amplitude-phase detection to...

In this paper, a detailed mathematical presentation of Photovoltaic (PV) generation system, as well its simulation model based on MATLAB / Simulink is established first. Its inverter-based simplified models, i.e. the switching-function equivalent and average model, are simulated compared quantitatively from different aspects. Simulation results reveal that with high accuracy in representing steady-state transient behaviors, suitable for Hardware-in-the-loop (HiL) applications. A novel phasor...

Hybrid energy storage system (HESS) is widely used in microgrids, and its research mainly focuses on management, power allocation, topology design so on. For the allocation issue, most only involves fundamental within a single HESS. While of reactive power, negative sequence harmonic coordinated operation multiple HESS units are rarely be studied. In response to above situation, this paper proposes coordination control strategy for group under unbalanced load nonlinear conditions. The...

Decaying DC (DDC) current due to impact loads causes detrimental consequences in weak grids. In this paper, the active power filter (APF) is enhanced simultaneously compensate for undesired harmonics, negative sequence components and DDC component event of a transient. To end, first, novel detection method mathematically deduced single-phase transient current, followed by its extension three-phase system. With respect existing techniques, proposed has significantly reduced time from 1 grid...