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Faults in the grounding grid are hidden danger to the safety of power system and cause significant economic loss every year. This paper presents a new means to locate faults in grounding grids using the transient electromagnetic imaging method. The method compares the distribution characteristics of the equivalent resistivity of underground covered by grids for no fault case and those with break points...
The paper investigates the applicability of averaged-value models (AVM) for modular multilevel converters (MMC) operating in a voltage sourced converter based high voltage dc (VSC-HVDC) grid. The AVM models are benchmarked by comparison with a detailed electromagnetic transient (EMT) model of the grid including a full-detail MMC model. Analysis results show that the AVM is only effective as long as...
IEEE Standard 1459 defines the power components based on the fast Fourier series. However, Fourier series assumes the signal is periodic in nature, and provides erroneous assessment of the power components in the presence of transient signals. Therefore, a new method is proposed for the evaluation of the IEEE Standard 1459 power components based on the time-frequency distribution (TFD) and the cross...
Zone 3 operation of distance relay serves as a remote backup in case of primary failure. Conditions, such as power swing, load encroachment, and voltage and transient instability, cause incorrect zone 3 operation. The detection of faults during such stressed conditions poses a further problem. This paper proposes a synchrophasor data-based technique for correct zone 3 operations by discriminating...
Power system operates close to its operational limit to achieve a higher level of utilization of the grid infrastructure. As a result, its transient behavior is of great importance to prevent violation of the operation limits. This paper proposes an internal model control (IMC)-based approach for voltage-sourced converters (VSC) to improve their dynamic behavior. This IMC controller is designed based...
This paper proposes a novel steady-state and transient management scheme for voltage source converter based high voltage direct current (VSC-HVDC) connecting permanent magnet synchronous generator (PMSG)-based offshore wind power plant (WPP). The proposed control arrangement aims to fully utilize the HVDC converters' normal loading capabilities during steady-state operation. Furthermore, it targets...
This paper concerns a novel approach to the modeling and control design for transient stabilization of electric power systems using Flexible Alternating Current Transmission System (FACTS) devices. A nonlinear dynamic model of general interconnected electric power systems in the Ordinary Differential Equation (ODE) form is proposed in terms of time-varying phasors of all dynamic components. This model...
This paper presents a novel approach to enable frequent computational cycles in online dynamic security assessment by using the terms of the transient energy function (TEF) as input features to a machine learning algorithm. The aim is to train a single classifier that is capable of classifying stable and unstable operating points independent of the contingency. The network is trained based on the...
This paper analyzes the dc line fault transient stability characteristics of AC/DC power systems based on three different modular multilevel converter based high power direct current (MMC-HVDC) configurations. The first configuration is half bridge sub-module based MMC (H-MMC) HVDC configuration, which clears dc line faults by tripping the ac circuit breakers. Voltage source converters (VSC) with...
Maloperation of zone 3 element of distance relay during stressed system condition such as power swing, load encroachment or voltage stressed condition is one of the main reason of large disturbances in power systems. Improved protection technique for zone 3 can help to prevent such maloperation and thus more reliable power system can be envisaged. This paper proposes an algorithm that utilizes two...
This paper provides recommendations for volt-VAr and voltage ride-through needs from distributed energy resources (DERs) to contain fault induced delayed voltage recoveries (FIDVRs) events and help stabilize the grid. FIDVR events can potentially cause chain reactions and destabilize the grid. Additionally, it will provide typical residential air conditioner (RAC) unit performance during voltage transients...
Modeling and simulation of power systems for general-purpose transient studies has been receiving significant attention in the literature. Among recently proposed methods, the so-called shifted-frequency analysis (SFA) approach has been shown to facilitate accurate and numerically efficient simulation of electromagnetic and electromechanical transients with the use of dynamic phasors. This paper proposes...
In the near future, transmission grids will include an increasing share of directly connected voltage source converters. These systems should be able to support the utility grid autonomously. The present paper reviews the most popular approaches to address the challenge of proper load sharing amongst multiple parallel inverters applied to the utility grid case. Originally developed for Microgrid or...
In this paper a typical 400 kV CVT is simulated for Ferroresonance and Transient Response conditions using Active and Passive Ferroresonance Suppression Circuits (FSCs) available in the literature. The effect of the FSC and other parameters on the transient response is analyzed. A novel thyristor based Electronic FSC is proposed in this paper which is suitable to suppress both the Ferroresonance and...
This paper presents a reclosing scheme for parallel lines on the same tower. The present reclosing scheme for parallel lines in China will result in opening both lines when any type of inter-circuit permanent fault occurs. In contrast, the proposed reclosing scheme is able to avoid opening both lines and keep a quasi-three-phase operation as far as possible for inter-circuit permanent faults, thus...
Currently, the standards used to calculate the short circuit (SC) current ignore the contribution of DC systems to the SC current when short-circuit faults occur in an AC systems. With the rapid development of High Voltage Direct Current systems (HVDC), it has become important to determine whether the contribution of the HVDC system can be ignored when calculating the SC current. This study investigates...
This paper describes an approach for determining generation-shedding for dynamic Remedial Action Scheme (RAS) based on minimum cost. A generation-shedding cost function is developed based on generator fuel cost, startup/shut down cost, and bid price. The proposed method updates RAS control actions online based on the system operating conditions and cost functions. The Single Machine Equivalent (SIME)...
This paper demonstrates the effectiveness of post-fault corrective control action through the planned Western HVDC link in the Great Britain (GB) transmission network. It is shown that both transient as well as oscillatory stability problems could be tackled using such a corrective control strategy which allows higher pre-fault loading of the AC network without compromising security. The corrective...
With the advent of smart-grid technology, the wide application of FACTS (Flexible AC Transmission Systems)- based damping controllers exerts influences on both small signal stability and transient stability. Traditional Modal Analysis (MA) method can hardly meet the requirements of online applications. According to the inter-area oscillation mode to be studied, the multi-machine system can be equivalent...
Three-phase reclosure with dead time is widely applied in robust grid, but its blind reclosing in the case of permanent faults or arcing transient faults may cause serious damage in power system. It is important to detect the nature of an earthed fault before reclosing for three-phase reclosure, which is helpful to improve successful reclosing rate and meet the increasing requirement on self-healing...
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