For the inverter-based distributed generation (DG) under constant power control, this paper analyzes relationship between active/reactive mismatch and frequency deviation, respectively, during islanding finds that variation trends caused by active reactive mismatches may be opposite. In order to eliminate nondetection zone (NDZ) detect rapidly, an innovative detection algorithm is presented based on a control strategy. The strategy provides reference for DG guarantee consistency of both...

This paper presents a novel active damping method to overcome instability problems of dc microgrids (MGs) caused by constant power loads (CPLs). is implemented based on the existing energy storage system (ESS) in MGs. As an indispensable part MGs, ESS this used for more than just compensating conventional unbalance system, it has taken additional responsibility and adjusting deal with induced CPLs as well. First, stability criteria simplified MG are analyzed. Based this, that aims at...

High-voltage direct-current (HVDC) transmission line protection is essential to the safety and reliability of modern power system with wide application HVDC technologies. Based on characteristics specific frequency current (SFC) dc filter, a novel pilot scheme for lines proposed in this paper. According harmonic equivalent circuit control strategy system, SFC filter are theoretically analyzed internal external faults fault steady period. In addition, these used construct backup identify...

In this paper, an islanding detection method for inverter-based distributed generators (DGs) is presented, which based on perturbing reactive power output. Two sets of disturbances are configured in method, have different amplitudes and duration time. The first set disturbance (FSORPD) periodic with small to break the balance during islanding, whereas magnitude second (SSORPD) sufficient force frequency deviate outside its threshold limits. Considering all possible variation characteristics...

In order to obtain the benefits of both passive and active methods, a well-designed hybrid islanding detection method for grid-connected microgrids with multiple inverter-based distributed generators (IBDGs) is presented in this paper. Considering that IBDGs located at different positions can detect same frequency variation (FV) characteristics, linear reactive power disturbance (RPD) utilized, which guarantee synchronization RPDs added on microgrid without need communication. addition,...

As a typical inductive type superconductive fault current limiter (SFCL), the saturated iron-core SFCL (SI-SFCL) is very important to safety of VSC-HVDC system. Considering that high-induced voltage winding may cause damage dc-bias source, an active SI-SFCL, which can quickly cut off source branch, introduced limit dc current. This paper first describes building transient analysis model SI-SFCL and, presents system equivalent circuit with deployed. Moreover, method solving state equations...

This article proposes an innovative DC line protection utilizing current correlation coefficient for hybrid cascaded high-voltage direct-current (HVDC) system. First, the equivalent discharge circuit after fault is inferred, and then characteristic analysis on superimposed network reveals that transmission lines connecting commutated converter (LCC) modular multilevel converters (MMCs), high-frequency currents of faulty non-fault are negatively correlated, their theoretically −1. Whereas,...

Faulty phase selection (FPS) methods are used to solve the problem of single ground fault (SPGF) in distribution network. When a false FPS (FFPS) issue occurs, short-circuit current faulty line suddenly increases. It is crucial diminish damages caused by FFPS and rapidly re-select phase. Therefore, this paper proposes fault-tolerant method based on an active-intervention-type arc suppression device with soft switch mode (AASD-SSM) fast wavelet packet transform (WPT). To strengthen...

This paper proposes a small-signal stability analysis method for the three-phase multifunctional grid-connected inverter (MFGCI) system with an unbalanced local load based on impedance modeling. To attenuate imbalance introduced by load, modified power quality-compensation algorithm MFGCI conservative theory is proposed and incorporated into analysis. The model of developed adopting complex space vector to simplify process in this paper. In addition, analysis, it proven that can affect when...

With the occurrence of major blackouts in "Australia 9·28" and "U.K. 8·9," technical bottlenecks power generation system with a high proportion renewable energy have attracted more attention. Based on this background, article studies control method that is suitable for AC microgrid strong current-limiting ability. First, outer loop controller adopts power-state equation based PI to achieve accurate tracking reference power. Furthermore, order make fault current having lower asymmetry degree...

The pole-to-ground fault is the most common in true bipolar modular multilevel converter based high voltage direct current (MMCHVDC) grid. study of a calculation method and characteristics theoretical basis for relay protection fast isolation technology MMCHVDC Considering mutual inductance coupling between lines, this paper proposes general faults grids. Firstly, considering influence AC system on MMC complex frequency domain equivalent model grid simplified remote station are studied....

Here, a novel active islanding detection method for inverter-based distributed generators (IBDGs) is presented. In order to reduce the disturbance in grid-connected mode and realise rapid effective during islanding, linear reactive power utilised proposed its slope can change adaptively. The voltage variation correlation factor between frequency are as criteria adjustment. addition, considering IBDGs located at different positions detect same characteristics, value of used control values,...

Abstract To address the impact of distributed generation (DG) access on traditional protection configuration methods distribution networks (DNs) and to facilitate swift effective lines by devices under fault conditions, an adaptive current method for three‐phase short‐circuit faults in active (ADNs), based local information, is proposed. Initially, applicability issues are examined, limitations existing scheme ADNs highlighted. Subsequently, characteristics analysed, taking into account...

The open-phase operation of the AC connection line connecting wind farm and MMC generates negative sequence current in system, which cause overcurrent, overvoltage, power fluctuation other problems. It seriously affects transmission equipment safety. Therefore, it is great significance to study suppression scheme suitable for master calculation method electrical quantities improving utilization rate ensuring stability system. Based on relationship between MMC, coordinated control schemes...

In order to detect islanding nondestructively, an detection method for microgrid is proposed based on adaptive and periodic disturbance the reactive power output of inverter-based distributed generation (DG). The first two parts in a cycle form symmetric triangular shape can adaptively adjust its peak value time purposes. One minimize total amount disturbance. other guarantee that absolute rate change frequency (ROCOF) constant during islanding, which be utilized criterion islanding. applied...

Due to the mismatched voltage amplitude, phase and frequency between virtual synchronous generator (VSG) utility grid, there may exist significant impulse current when VSG connects gird through point of common coupling (PCC). This paper designs a NLADRC-PLL proposes novel pre-synchronization control strategy decrease current. Firstly, lock loop based on nonlinear active disturbance reject (NLADRC-PLL) is designed obtain information PCC quickly flexibly. Then, obtained by embedded into both...