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This paper presents model for Modular Multilevel Converter (MMC) in phasor format, which is convenient for power flow and parameter studies. The model is derived in rotating dq coordinate frame, and the coordinate frame at double the fundamental frequency, in steady-state. A substantial analytical basis is presented in order to facilitate direct mathematical manipulations of non-linear terms in the...
This paper studies the feasibility of utilizing the reactive power of grid-connected variable-speed wind generators to enhance the steady-state voltage stability margin of the system. Allowing wind generators to work at maximum reactive power limit may cause the system to operate near the steady-state stability limit, which is undesirable. This necessitates proper coordination of reactive power output...
This paper presents the load flow modeling and steady-state capabilities of the bundle-controlled Line Impedance Modulator (LIM). This distributed FACTS device is under development for the management of power flows. In particular, the paper presents the back-to-back interconnection of two Bundle-Controlled Line (BCL) segments. The LIM configuration is very interesting from an economic and operational...
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...
The major obstacle toward wind farm integration is power mismatch between wind output and grid desirable generation due to wind uncertainty and negative effect on peak load regulation. Storage can be used as assistance to reduce this mismatch. Needed storage capacity for full level of assistance is acceptable only for small-scale wind farm with qualified matching requirement. But when it comes to...
This paper describes enhancements to ATC's cascading study criteria and the implementation of a fast automated process using POM/OPM software for conducting comprehensive steady state multiple element contingency screening and cascading analysis, finding mitigations to restore the system to be within emergency and/or normal performance limits, and automatically tabulating significant results and summaries...
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...
This paper proposes an operational improvement of MMC (Modular Multilevel Converter) with redundancy SMs (sub-modules) by a new scheme of NLC (Nearest Level Control), which can offer reduction of voltage harmonics and switching loss. The feasibility of proposed scheme was verified through computer simulations with PSCAD/EMTDC software. Based on simulation results, a hardware prototype of 10kVA, DC-1000V...
Proportionate sharing of load changes in a microgrid without communication among the generators is a difficult problem. In this paper an exact power sharing algorithm is developed that uses an optimization-based technique to minimize the exchange of state information among the generators. To demonstrate the application of the developed framework we present simulation results for a system constructed...
The Static Security Assessment of power system is affected by the uncertainty of the power flow distribution introduced by renewable resources. In this paper, a fast contingency selection approach considering load and generation uncertainties is proposed. Firstly, a linearized interval power flow algorithm is developed for post-contingency simulation. Then, an interval number comparison method based...
Increasing distributed energy resources introduce rapid and fast fluctuations in power supply and demand. As a result, the control and economic optimization for power networks need to operate at faster time-scales for reliability and economic efficiency. In this paper, we consider the problem of achieving real-time economic dispatch for power networks with controllable loads. We first present system...
We adapt and apply a known algorithm for Distributed Moving Horizon Estimation (DMHE) to power systems. In this distributed approach, the power system is partitioned into several control areas. At each time step the state of the whole system is estimated locally in each area, by solving a local optimization problem. A consensus weights update step is performed in which the covariance matrix of the...
The existing steady-state models for the permanent magnet synchronous generator (PMSG) are based on the constant voltage, or quantify electromagnetic transient. This paper proves that the equivalent voltage behind stator circuit is proportional to the rotor speed, and dependent on wind speeds, thus invalid. The steady-state constraints are proved to be indeterminate equations, whose unique solution...
This paper proposes a decoupling based direct method to analyze the post-contingency transient stability for a general multi-machine power system. A linear decoupling transformation is used to construct the same number of independent single machine infinite bus (SMIB) power systems as oscillation modes. Each SMIB system carries stability information regarding one oscillation mode of the original system...
This paper presents MatLVDC, i.e. an open source Matlab toolbox to analyse dynamic phenomena in DC distribution networks, that are gaining importance because of reported energy savings and the increasing number of DC loads and distributed energy resources (DER). The toolbox aims at facilitating the design processes and research on DC distribution networks including a high share of renewable energy...
The paper discusses two evaluation methods of single pole auto-reclosing process effectiveness in HV transmission lines. Secondary arc current and recovery voltage calculation results obtained by load flow calculation are compared to the results obtained by the time domain simulations. Moreover, a nonlinear secondary arc model implementation is presented. The paper presents the study results for the...
This paper focuses on improving the solving performance of steady-state preventive security-constrained optimal power flow problem in large-scale power systems, which introduces compensation method to the established simplified model for deriving system state under post-contingency, in the end, interior point method is adopted to solve this optimization problem. This approach brings two benefits compared...
The voltage droop control concept is the most appropriate strategy to provide primary control in multiterminal VSC-HVDC (MTDC) transmission systems. However, due to voltage drops in the dc lines/cables, the primary power balancing is influenced by the dc grid topology and line resistances. This phenomenon is also evident when determining the secondary control strategy in MTDC systems. In this paper,...
A method that exploits Thevenin equivalent representation for obtaining post-contingency steady-state nodal voltages is integrated with a method of detecting post-contingency aperiodic small-signal instability. The task of integrating stability assessment with contingency assessment is challenged by the cases of unstable post-contingency conditions. For unstable postcontingency conditions there exists...
This paper describes the application of parallel processing techniques based on graphic processing units (GPUs) to the fast steady state solution of electric power systems. A Newton technique based on a Numerical Differentiation (ND) procedure is used. Conventionally, this technique requires of a significant computational effort, measured in terms of computation time. Parallel processing technology...
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