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In this paper, a new synchronous machine model is developed for electromagnetic transients program type simulations. The stator circuit is expressed in the abc phase domain. The machine model is represented as a Norton equivalent with a current source in parallel with a constant Norton admittance. The machine equations are reformulated so that the computational effort required for the modeling of the machine is reduced. Test studies demonstrate the accuracy of the proposed synchronous machine model and show that the proposed model is computationally more efficient than the existing constant conductance phase domain model and voltage-behind-reactance model. [ABSTRACT FROM AUTHOR]

Large-scale integration of wind generation changes the power swing characteristics of a power system and may result in the misoperation of legacy power swing protection schemes. This paper presents a qualitative study on the impact of wind generation on power swing protection. The objective is to provide an understanding of the problem through case studies and present possible solutions and adjustments in protection schemes to ensure the efficiency of protection under large-scale integration of wind generation. The misoperation of power swing protection functions, namely power swing blocking and out-of-step tripping (OST), as a result of increased wind generation levels, are shown through case studies. It is also shown that the electrical center of a power system may move due to wind generation. In this case, it would be necessary to revise the optimal location of the OST protection. Finally, the impact of various factors, such as wind generator type, control scheme and fault-ride-through function, and wind generation level and capacity are investigated to determine the key features that need to be accounted for in practical protection studies. [ABSTRACT FROM AUTHOR]

Recently, Andreotti et al. (2015) have presented a new tool for lightning induced voltage calculations on power networks. This tool, named Circuit for Lightning Induced Voltage (CiLIV), has been initially developed for straight and vertical lightning channels; afterwards, the tool has been extended to evaluate induced voltages produced by tortuous lightning channels. However, in the aforementioned studies, only simple power network configurations have been examined. Therefore, aim of this paper is twofold: 1) to apply CiLIV to more complex network configurations, that is, complex networks equipped with transformers, surge arresters, groundings, and so on; 2) to investigate the effects of channel tortuosity on the voltages induced in these complex networks. [ABSTRACT FROM PUBLISHER]

Special protection schemes (SPSs) are an efficient alternative to increase the flexibility in the operation of power systems. The implementation of SPSs is often motivated by technical rather than economic reasons. The aim of this paper is to propose a novel framework for the analysis and development of SPSs in a context from the Chilean experience that comprises both technical and economic incentives to enable high penetration of solar energy. With this purpose, this paper explores the new capabilities of SPSs based on maximizing the cost-effective integration of solar power into a power system, given a set of technical challenges (congestion and dynamic response in case of contingencies) that must be considered in their design. In this framework, three main drivers were identified and discussed. The discussion includes the mechanisms associated with each driver that promote the massive integration of solar power. Moreover, within the proposed technical-economic framework, a methodology for driver selection and SPS design is proposed. The methodology and the drivers identified are evaluated in the Chilean power system. [ABSTRACT FROM AUTHOR]

The improper operation of the third-zone distance protection has been attributed as one of the factors for power system blackouts. The third-zone protection could incorrectly operate during power-swing scenarios. This research proposes a fast and practical methodology using local measurements for blocking the third-zone distance relays during stable power swings. The proposed scheme is referred to as the BTZ scheme. The proposed method calculates the relative speed of a fictitious equivalent machine from the local relay measurements. If the relative speed goes through a zero crossing, the swing is classified as a stable power swing; whereas if the speed does not go through a zero value, then the swing is classified as an unstable power swing. The benefit of the proposed method is that it analyzes the power swings from a system stability point of view, and does not need rigorous offline simulation studies to determine the relay settings. The performance of the proposed method in this paper is compared with an industry-standard method (conventional double blinder method). As is well known, the settings of the blinder-based methods are system specific and need several simulations to arrive at the blinder values. Transient simulation studies on a three-bus system and a modified Western Coordination Council 9-bus system are used to test the performance of the proposed approach. [ABSTRACT FROM PUBLISHER]

The electromagnetic transient (EMT) simulation of a large-scale power system consumes so much computational power that parallel programming techniques are urgently needed in this area. For example, realistic-sized power systems include thousands of buses, generators, and transmission lines. Massive-thread computing is one of the key developments that can increase the EMT computational capabilities substantially when the processing unit has enough hardware cores. Compared to the traditional CPU, the graphic-processing unit (GPU) has many more cores with distributed memory which can offer higher data throughput. This paper proposes a massive-thread EMT program (MT-EMTP) and develops massive-thread parallel modules for linear passive elements, the universal line model, and the universal machine model for offline EMT simulation. An efficient node-mapping structure is proposed to transform the original power system admittance matrix into a block-node diagonal sparse format to exploit the massive-thread parallel GPU architecture. The developed MT-EMTP program has been tested on large-scale power systems of up to 2458 three-phase buses with detailed component modeling. The simulation results and execution times are compared with mainstream commercial software, EMTP-RV, to show the improvement in performance with equivalent accuracy. [ABSTRACT FROM AUTHOR]

A method is proposed in this paper to determine the frequency-dependent loss of power transformer for very fast transient simulation. The attenuation factors and the corresponding natural frequencies of the transformer at measurable range were extracted using measured power transformer network functions and the vector-fitting method (VFM). The approximate frequency-dependent formula of attenuation factors was established by analyzing the theoretical transformer model. Then, the parameters in the formula were optimized by fitting the real part (attenuation factors) and imagine part (natural angular frequencies) of poles obtained by VFM. The time-domain simulation process can be divided into two steps. First, the lossless transformer transient response, which could be expressed as the sum of the natural frequency components, is obtained by solving the network differential equations. Second, the attenuation factors calculated by the approximate formula are added directly on the corresponding frequency components. By comparing with the measured results, it is shown that the proposed fitting formula for calculating the attenuation factors could improve the simulation accuracy in comparison with the existing methods. [ABSTRACT FROM AUTHOR]

This paper proposes the use of Sprott chaos synchronization (SCS)-based voltage relays for fault protection in microdistribution systems (MDSs). The Sprott chaos system is used as a voltage detector to track the dynamic errors between the normal signal and disturbance signals. The proposed voltage relay is used to detect disturbances, such as serious voltage sag and swell, and uses a critical trigger time to isolate the fault section. It is proposed that the restoration strategy then restores the unfaulted but blackout zones, and confirms security operations, including load-power balance, power generation limits, voltage limits, and power-flow limits. Computer simulations are conducted by using an IEEE 30-bus power system and MDSs, to show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The scope of this paper is the investigation of the development of fault currents in a circuit breaker (CB) during a pole-to-ground fault in a generic multiterminal HVDC cable system based on voltage-source converters. It aims to contribute to the current discussion of which requirements on breaking time and peak current HVDC CBs need to fulfill in such networks. Therefore, the fault current is broken down into the individual contributions from the different network components, and the influence of the key parameters on the development of the fault current in the CB of the faulted cable is illustrated. [ABSTRACT FROM PUBLISHER]

The unified power-quality conditioner (UPQC) is used to mitigate the current and voltage-related power-quality (PQ) problems simultaneously in power distribution systems. Among all of the PQ problems, voltage sag is a crucial problem in distribution systems. In this paper, a new methodology is proposed to mitigate the unbalanced voltage sag with phase jumps by UPQC with minimum real power injection. To obtain the minimum real power injection by UPQC, an objective function is derived along with practical constraints, such as the injected voltage limit on the series active filter, phase jump mitigation, and angle of voltage injection. Particle swarm optimization (PSO) has been used to find the solution of the objective function derived for minimizing real power injection of UPQC along with the constraints. Adaptive neuro-fuzzy inference systems have been used to make the proposed methodology online for minimum real power injection with UPQC by using the PSO-based data for different voltage sag conditions. The proposed method has been validated through detailed simulation and experimental studies. [ABSTRACT FROM AUTHOR]

Increasing shares of fluctuating renewable energy sources induce higher and higher power flow variability at the transmission level. The question arises as to what extent existing networks can absorb additional fluctuating power injection without exceeding thermal limits. At the same time, the resulting power flow characteristics call for revisiting classical approaches to line temperature prediction. This paper presents a probabilistic modeling and simulation methodology for estimating the occurrence of critical line temperatures in the presence of fluctuating power flows. Cumbersome integration of the dynamic thermal equations at each Monte Carlo simulation trial is sped up by a specific algorithm that makes use of a variance reduction technique adapted from the telecommunications field. The substantial reduction in computational time allows estimations closer to real time, relevant to short-term operational assessments. A case study performed on a single line model provides fundamental insights into the probability of hitting critical line temperatures under given power flow fluctuations. A transmission system application shows how the proposed method can be used for a fast, yet accurate operational assessment. [ABSTRACT FROM AUTHOR]

In this paper, the authors present a method to synthesize a power autotransformer model that takes into account high-frequency effects. The proposed procedure implements data usually available for this kind of transformer: the results of lightning electromagnetic pulse tests generally carried out on these machines in accordance with standard prescriptions. Furthermore, it makes use of a well-established model synthesis technique, namely, the fast relaxed vector fitting. A simple application example, involving lightning overvoltage effects, is also described in order to compare model behavior with simplified approaches. [ABSTRACT FROM AUTHOR]

This paper deals with the current state-of-the-art in interfacing issues related to real-time digital simulators employed in the simulation of power systems and power-electronic systems. This paper provides an overview of technical challenges encountered and their solutions as the real-time digital simulators evolved. Hardware-in-the-loop interfacing for controller hardware and power apparatus hardware are also presented. [ABSTRACT FROM AUTHOR]

This paper reviews different methodologies for interfacing time-domain and frequency-domain simulation programs. The main objective for this interface is to obtain the steady-state or transient state of a power network containing linear and nonlinear loads, and the calculation of the corresponding harmonics and the foregoing values for different types of analyses in power systems. [ABSTRACT FROM AUTHOR]

In this paper, two methods for analyzing nonuniform multiconductor transmission lines in the frequency domain are considered. The first one is based on the cascaded connection of chain matrices of uniform line segments. In the second method, a space-variant linear system is solved. Besides, a technique to introduce the effect of incident electromagnetic fields into the nonuniform line model is presented. To obtain the solution in the time domain, the numerical laplace transform (NLT) is applied. Several application examples are analyzed, and comparisons with the ATPIEMTP and with experimental measurements published elsewhere are provided. [ABSTRACT FROM AUTHOR]

This paper introduces a method for power system modeling during the earth fault. The possibility of using this method for selection and adjustment of earth fault protection is pointed out. The paper also contains the comparison of results achieved by simulation with the experimental measurements. [ABSTRACT FROM PUBLISHER]

In real time digital simulation of electromagnetic transients for equipment testing, solution output is provided at equidistantly spaced time points in order to synchronize the data exchange with external equipment. Switching events, which can occur in between these time points of solution output, are pinpointed by backward interpolation. To recuperate the time interval lost through interpolation, the simulation must be resynchronized with the real time clock. For this purpose, the use of a flexible time step size is desirable. However, in EM transients simulators based on nodal analysis techniques, time step size changes have so far involved changes of the nodal admittance matrix and, thus, imposed a large computational burden. This is avoided through the method flexible integration for readjustment in simulation of transients (FIRST), presented in this paper. Through this method, the characteristics of numerical integration are modulated such that time step size changes are achieved in a computationally very efficient manner and without modifying the nodal admittance matrix. [ABSTRACT FROM AUTHOR]

Previously, a method for identifying a multiphase network equivalent for electromagnetic transient calculations using partitioned frequency response has been proposed. The method accurately and robustly identities an equivalent of the target network by dividing its frequency response into sections, but no specific algorithm for the frequency-region partitioning has been proposed. To make the entire identification process automatic, this letter proposes a binary partitioning algorithm. [ABSTRACT FROM AUTHOR]