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Multiport Converter gets growing applications due to its advantages of flexible control mode, high power density, bidirectional power delivery capability etc. In this paper, a DAB based partial isolated DC-AC multiport power converter, which combines photovoltaic panel, battery storage and grid connection is studied. Modulation method, analysis for power transmission and control design are provided...
Buildings are important places and parts in the society. The conventional power supply of a building is AC power from the utility grid. As the growing penetration of renewable energy source and DC loads, it becomes practical and common for a building supplied by the distributed generators with DC power. Considering this unprecedented transition from the conventional AC building to the hybrid AC/DC...
This paper presents a novel Kriging surrogate model based optimization algorithm to solve the constrained optimal operation problem in unbalanced three-phase distribution system, which is a mixed-integer, no-convex and nonlinear programming problem. The objective function is to reduce the power loss and to lower the voltage deviation. Considering that the traditional solving methods, such as GA and...
An impact increment-based state enumeration (USE) method is designed to assess reliability of composite generation and transmission systems. The reliability index calculation formula of the traditional state enumeration technique is transformed into an impact increment-based formation. Based on the derived equation, the traditional state enumeration method is modified into an impact increment based...
This paper proposes a simplified microturbine (MT) model which allows for dynamic heat and power output prediction. Considering the time-scale difference of various dynamic processes occuring within MTs, the electromechanical subsystem is treated as a fast quasi-linear system while the thermo-mechanical subsystem is treated as a slow process with high nonlinearity. A subspace model identification...
This paper develops an integrated optimal power flow (OPF) tool for distribution networks in two spatial scales. In the local scale, the distribution network, the natural gas network, and the heat system are coordinated as a microgrid. In the urban scale, the impact of natural gas network is considered as constraints for the distribution network operation. The proposed approach incorporates unbalance...
This paper presents a novel method to evaluate the Volt-VAR interactions among the buses using relative gain (RG). Following the viewpoint of a multi-input-multi-output system, the Volt-VAR coupling RG is calculated based on the QV matrix which is extracted from power flow Jacobian matrix to evaluate the Volt-VAR interactions among the buses. The voltage stability weak buses are identified through...
In this paper, a new approach based on dynamic relative gain is proposed for partitioning voltage control areas in bulk power systems. The critical nodes of voltage stability are determined using voltage stability index, “L index”. The cross relative gain between the critical nodes and other nodes are calculated based on the concept of dynamic transfer function (DTF) and dynamic cross relative gain...
This paper proposes a continuous time Markov chain (CTMC) based sequential analytical approach for composite generation and transmission systems reliability assessment. The basic idea is to construct a CTMC model for the composite system. Based on this model, sequential analyses are performed. Various kinds of reliability indices can be obtained, including expectation, variance, frequency, duration...
In order to fully take advantage of the available reactive power from EV chargers (EVCs), a volt-var optimal control (VVOC) strategy for power system integrated with wind farms is proposed. The VVOC strategy consists of two steps: day-ahead optimal scheduling and intra-day optimal adjustment. In the first step, on-load tap changers (OLTCs) and capacitor banks (CBs) are scheduled to minimize the power...
In modern power systems, the integration of variable and random renewable energy brings more challenges to real-time voltage stability monitoring and control. Loading margin sensitivity (LMS) is an index that is widely-used to evaluate voltage stability. The accuracy of LMS relies on the credibility of the data collected by local measurement units, which are used to estimate the system model parameters...
In this paper, a building based virtual storage system (VSS) model is developed by utilizing the heat storage characteristics of the building. Then, the VSS is integrated to the optimal scheduling model of the building microgrid (BM) for operation cost reduction. The indoor temperature of the building is adjusted within the customer temperature comfort level range to manage the charging/discharging...
This paper proposes an impact increments-based state enumeration (IISE) reliability assessment approach, specially designed for transmission systems. Firstly, the reliability index calculation formula of the traditional state enumeration technique is transformed into an impact increments-based formation. With the derived formula, the calculation of state probability is simplified and the weight of...
GaN HEMT devices provide significant advantages over silicon MOSFET with lower gate charge, faster switching speed and smaller reverse recovery charge. It is hopeful to use this device to get high efficiency and high power density compatibly. A GaN HEMT device based full-bridge single-phase inverter with switching frequency 260kHz is proposed to evaluate the advantages of GaN power transistors in...
The theoretical modeling and analysis of a feedforward decoupling based induction motor system with rotor field orientation control is presented in this paper. Small signal approximation is employed to get the output impedance and input impedance of the whole drive system with consideration of non-ideal power source. An oscillation compensation technique is proposed to improve the stability margin...
LLC resonant converter is concerned for its inherent soft switching features. What's more, Gallium Nitride high electron mobility transistors (GaN HEMT) has smaller on-state resistor and much smaller gate charge and junction capacitors compared with the silicon MOSFET. In this paper, a LLC resonant converter with high efficiency based on 600V GaN HEMT is presented. Controller design procedure is discussed...
From the point of view of project maturity, this paper builds the maturity assessment model of smart grid project. Based on the general rules of the smart grid project, the assessment model evaluates smart grid project comprehensively, including technical maturity of key technology of the project, project policy and environment, project management level and project business model. In this paper, the...
The application of advanced technologies is one of the key differences between smart grid and traditional grid. Its development and application will be through various periods and field of the construction of smart grid. This paper establishes a comprehensive evaluation index system for smart grid technology. The whole index system has the general characteristics, which can evaluate the technology...
A Volt-VAR control (VVC) strategy by using voltage regulators and reactive power compensators in the modern distribution grid for renewable energy integration is presented in this paper. Currently, the VVC techniques are gaining renewed interest and attention due to the emergence of active distribution grid, which refers to the distribution grid with advanced capability of computation, control and...
With the increasing utilization of combined heat and power plants (CHP), electrical, gas, and thermal systems are becoming tightly integrated in the urban energy system (UES). However, the three systems are usually planned and operated separately, ignoring their interactions and coordination. To address this issue, the coupling point of different systems in the UES is described by the energy hub model...
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