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Extended equal area criterion method (EEAC) is always applied for transient stability analysis of large scale power system. The coherency identification of generators clusters after accidents is on the basis of EEAC Method, and the coherency identification of generators clusters used to take the complex power angle method as the criterion, which consume a lot of time and possess a relatively inefficient...
An improved time-domain online dynamic equivalent method is presented, which is suitable to shipboard power systems (SPS) and based on the coherency technique. It preserves the structure of the generator, excitation system and governor system, and the time-domain non-iterative algebraic operations process is used to calculate equivalent parameters. Sixth-order generator equation is used to reduce...
Small generators are commonly incorporated in the electrical systems of large industrial plants, i.e. oil, gas, and petrochemical industries, for ensuring continuous and high quality energy supply to critical loads. In case that local generation is enough to satisfy the demand of the plant, then the interconnection with the public grid is commonly used as an important support for emergency conditions...
Based on the transient energy function (TEF) theory with classical models considered, the optimal re-closing time (ORT) can be calculated accurately. This paper mainly focuses attention on the validity and practicability analyzing of ORT obtained from this method. Firstly, the characteristics and influencing factors of the ORT are put forward and analyzed, and also the setting strategy of re-closing...
At stressed operating conditions, critical contingencies can initiate loss of synchronism and trigger cascading events. Controlled islanding is the last line of defense to stabilize the whole system. This paper presents a decision tree assisted scheme to determine the timing of controlled islanding in real time by using phasor measurements. In addition, a slow coherency based approach is used to determine...
As PV - distributed generation (DG-PV) penetration increases, its reaction with various system disturbances (i.e. voltage drop, short circuit, frequency deviation) has to be taken into account during relative system studies. Though for wind farm generation (WFG) a lot of effort has been made for the development of appropriate models, there is still a lot of progress to be done in the field of PV Generation...
In this paper, robust stabilizing controllers for the synchronous generator speed, series power flows, voltage magnitude and DC link voltage are designed for a power system with FACTS device (UPFC). To design these controllers, a combined Super-twisting sliding mode (SM) and block control (BC) technique is implemented. The block control approach is used to design linear and nonlinear sliding manifolds...
With the scenario of wind power constituting up to 20% of the electric grid capacity in the future, the need for systematic studies of the impact of wind power on both voltage and transient stability of the grid has increased. A large number of parameters will affect such studies. For this paper, studies were conducted on a standard three-machine, nine-bus system augmented by a radially connected...
This paper proposes a real-time wide area protection system which incorporates artificial neural networks (ANN) for transient stability prediction. The ANN makes use of the advent of phasor measurements units (PMU) for real-time prediction. Rate of change of bus voltages and angles for six cycles after fault tripping and/or clearing is used to train a two layers ANN. Coherent groups of generators...
Dynamic model of a variable speed wind generation system connected to grid is developed, and its steady state and dynamic performance is explored. The performance under wind gust and three-phase fault has been studied and the amount of transient injection to the grid is also investigated. A control scheme that minimizes the transient injection through a thyristor controlled variable capacitance at...
The re-closing time of a transmission line has a distinct influence on power system transient stability. There is an optimal re-closing time (ORT) for all transmission line faults, no matter the instantaneous fault or permanent one. Based on the transient energy function (TEF) theory with classical models considered, the ORT can be calculated accurately. This paper mainly focuses attention on the...
Renewable energy driven distributed generators (DGs) are mostly connected to radial distribution network with overhead feeders. It is estimated that 80% of network faults are temporary single phase to ground faults and therefore automatic restoration is required. A combination of automatic re-closer devices, circuit breaker, sectionalizer and fuse is applied to clear the temporary fault and isolate...
In this paper, coordinated control of multiple HVDC links in a small AC/DC power system is investigated. A coordinated control strategy is proposed to increase the transient stability and the damping in the AC/DC system. The system power loading is set by the well-known N - 1 criteria, i.e. that the system should remain intact (in the sense of both transient and small-signal stability) despite the...
The objective of this paper is to investigate the method which can assess accurately and efficiently the effects of control systems for turbo-generators on transient stability of power systems. At first, critical fault clearing time functions CCT(W:load) are defined by taking notice of the fact that transient stability is mainly controlled by fault clearing time and load. Next, the method which can...
Advanced power system experiment facilities and the contents are shown. It is important to show undergraduate students that there are certain advancements in power system experiments from both hardware and software aspects to attract them to the power and energy areas. The facilities use digital measurements to be used for computer interfaces, and can set experiment conditions using screen inputs...
Electromechanical transients are studied using transient stability simulators with differential-algebraic equation (DAE) models employing phasor network variables. While these simulators can follow the electromechanical transients (e.g., voltage and power swings) due to large disturbances with loads modeled as constant impedance, they may fail to converge under voltage collapse conditions for systems...
Recognizing that power system blackouts are likely to occur, it is prudent to consider the necessary measures that reduce their extent, intensity and duration. Immediately after a major disturbance, the power systempsilas frequency rise and decay are arrested automatically by various control and protection schemes. The success rate of these automatic mechanisms has been about 50%! The challenge is...
A new comprehensive approach is presented to improve the power swings damping of power systems. While the approach integrates the unified power flow controller (UPFC) and superconducting magnetic energy storage (SMES), employs direct Lyapunov method concept to determine the control scheme based on nonlinear power system model. It is shown that in transient states, SMES cooperates with the UPFC converters...
This paper addresses simultaneously the major fundamental and difficult issues of nonlinearity, uncertainty, dimensionality and globality to derive performance enhancing power system stability control. The main focus is on simultaneous enhancement of transient stability and voltage regulation of power systems. This problem arises from the practical concern that both frequency and voltage control are...
This paper presents a laboratory setup for transient testing of relays and GPS-synchronized devices. The setup relies on a unique, realistic scaled model of a small three substation system, along with its metering equipment. Lumped models of transmission lines are included that realistically represent the mutual couplings between the phases and asymmetries. Two phase shifters provide loading controllability...
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