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Advanced spatio-temporal electric load modeling and accurate spatio-temporal load forecast are essential to both short-term operation and long-term planning of power systems. This paper explores the spatio-temporal dependencies of electric load time series. The Southern California feeder load data show that feeders which are spatially close to each other share a more similar load pattern than those...
This paper presents a method for the identification of critical locations of power systems using the measurable variables of the active distribution grids. The critical locations are identified using sensitive sparse principal component analysis (SSPCA) where the loadings of some variable in principal components are restricted to zero. SSPCA is tested on the UK 77-bus system. Furthermore, SSPCA and...
An appropriate operating principle of voltage source converter based high voltage direct current (VSC-HVDC) is able to further affect the sensitivity to voltage unbalance. The new HVDC system based on voltage source has broadened application prospect for its beneficial characteristics compared with the traditional DC transmission system. In the paper, a simple and effective simulation model of VSC-HVDC...
This paper provides an analyses on the steady-state of electric spring (ES) for stabilizing future smart grid with intermittent renewable energy sources. The objectives of this work are to reveal the working principle of ES for providing voltage support to the power grid, and to provide theoretical basis for the design of ES. This work is focused on the steady-state characteristics of ES. With respect...
In this paper, operation and analysis for an improved transformer-less unified power flow controller (UPFC) is presented. As is well known, the conventional UPFC that consists of two back-to-back inverters requires bulky and often complicated zigzag transformers for isolation and reaching high power rating with desired voltage waveforms. To overcome this problem, a completely transformer-less UPFC...
Model checking suffers from the state space explosion problem. Compositional verification techniques such as assume-guarantee reasoning (AGR) have been proposed to alleviate the problem. However, there are at least three challenges in applying AGR. Firstly, given a system M1 ? M2, how do we automatically construct and refine (in the presence of spurious counterexamples) an assumption A2, which must...
A new unity power factor control strategy for electrically excited synchronous motor(ESM) based inertia wheel energy storage system by high power back-to-back converter is proposed. In EMS control system, there are three objects from the control consideration, i.e. the stator flux, the power factor, and the DC-link voltage. In this paper, we compute only in rotor-oriented reference frame. Field operation...
A transformer-less UPFC based on an innovative configuration of two cascaded multilevel inverters (CMIs) has been proposed recently, which is suitable for power flow control between two interconnected synchronous AC grids. The active power as well as the reactive power can be independently controlled by the new transformer-less UPFC. In addition, the semiconductor device ratings (SDPRs) for different...
This paper shows a comparison between synchronous condenser (SC) and STATCOM in terms of inertia frequency response (IFR) with synchronous generator (SG). It has long been argued that, as a rotating-mass-based reactive power compensation device, SC will contribute to the total inertia of the network from its stored kinetic energy. Whereas, its counterpart, the voltage source converter (VSC) based...
The paper is talked about a new current tracking control method for low-voltage high-power active power filter. The main circuit topology of APF adopts a three-phase three-line voltage source converter??which is constituted by three H-bridges. Current tracking control method of APF determines the APF performance. For high-power APF, the switching frequency of APF system is difficult to improve, resulting...
Service composition makes use of existing service-based applications as components to achieve a business goal. In time critical business environments, the response time of a service is crucial, which is also reflected as a clause in service level agreements (SLAs) between service providers and service users. To allow the composite service to fulfill the response time requirement as promised, it is...
Modeling and verifying complex real-time systems, involving timing delays, are notoriously difficult problems. Checking the correctness of a system for one particular value for each delay does not give any information for other values. It is hence interesting to reason parametrically, by considering that the delays are parameters (unknown constants) and synthesize a constraint guaranteeing a correct...
High level specification languages like CSP use mathematical objects as abstractions to represent systems and processes. System behaviors are described as process expressions combined with compositional operators, which are associated with elegant algebraic laws for system analysis. Nonetheless, modeling systems with non-trivial data and functional aspects using CSP remains difficult. In this work,...
This paper proposes a dc power supply system to give high power factor and low current distortion on the rectifier side and provide stable dc voltage on the isolated dc/dc converter side. The proposed dc power supply system uses a new ZVS strategy to get ZVS function. Besides operating at constant frequency, all semiconductor devices operate at soft-switching without additional voltage stress. A significant...
This paper proposes a new single-phase high power factor rectifier, which features regulation by conventional PWM, soft commutation and instantaneous average line current control. A zero-voltage-switching pulse-width modulation (ZVS-PWM) auxiliary circuit is configured in the presented ZVS-PWM rectifier to perform ZVS in the main switches and the passive switches. Furthermore, soft commutation of...
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