In order to analyze the impact of variations of key parameters, such as load model and fault time etc., on powersystemdynamic stability, this paper applies a new method-the stochastic response surface method (SRSM) ...
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In order to analyze the impact of variations of key parameters, such as load model and fault time etc., on powersystemdynamic stability, this paper applies a new method-the stochastic response surface method (SRSM) to analyze uncertainties of these parameters. Polynomial expressions between parameters and responses of system can be established by this method. Compared with the traditional approaches, the presented method can obtain statistical information with less simulation time. The case study on the IEEE 9-bus system demonstrates the validity of SRSM. Simulation results on the IEEE 39-bus system show that the uncertainties from key parameters, especially the different load model structures, have great impact on powersystemdynamic stability, which is directly related to the security and stability of powersystems.
It is difficult to measure the circulating current in delta windings of Y, d connected transformer. So the current phase compensation has to be considered for transformer differential protection. In this study, a prop...
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It is difficult to measure the circulating current in delta windings of Y, d connected transformer. So the current phase compensation has to be considered for transformer differential protection. In this study, a proportional relationship between the zero sequence current in Y winding and circulating current in delta winding is derived based on the differential equations of transformer. If phase A is closed exactly in 90 by controlled switching, the part of the line current of phase A is almost equal to the circulating current. By using the correlative formula, the correlative coefficient of line current of phase A and zero sequence current in Y side is calculated so as to distinguish parts of line current, with and without influence of inrush. Then the ratio between the zero sequence current and the circulating current, and the circulating current can be calculated as well. Finally the algorithm is verified with MATLAB and RTDS simulation. The results show that the calculated circulating current is identical with the actual one accurately, and it offers a new algorithm method for the differential protection and the equivalent transient inductance.
The mal-operation of transformer differential protection will occasionally take place after the removal of external fault due to current-transformer (CT) saturation. Study show that CT saturation can be divided into t...
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The mal-operation of transformer differential protection will occasionally take place after the removal of external fault due to current-transformer (CT) saturation. Study show that CT saturation can be divided into three kinds. Firstly, the influencing factors of CT saturation and effect of CT saturation to transformer differential protection are studied. Secondly, this paper analyzes the characteristic of the operating point when differential protection is mal-operated because of CT saturation. At last a method of different time delay in different areas is presented to prevent the differential protection from maloperation. Simulation results validate its feasibility and reliability. It is significant if the method is realized for transformer protection.
Assessment of load's disturbing property needs to be studied for confirming power quality responsibility and making a power price by its quality. In this paper, load's disturbing property is assessed by means ...
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As the most important tool guiding the powersystem operation and control, digital simulation directly affects the secure and economic operation. Consequently, the dynamic simulation validation work has been highly fo...
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ISBN:
(纸本)9780947649289
As the most important tool guiding the powersystem operation and control, digital simulation directly affects the secure and economic operation. Consequently, the dynamic simulation validation work has been highly focused recently. This paper proposes a new method to implement the Hybrid dynamic simulation. With this method, the data from Wide Area Measurements (WAMs) can be injected into the simulations, thus a big power grid is decoupled into several small systems. All data in these small systems are kept when the conventional digital simulation is carried out, while the boundaries of these small systems are replaced by the signals of WAMs. Then the space to search the erroneous component is limited to the decoupled system, which is much smaller with fewer components. Case studies show the efficiency of the proposed method in simulation validation work.
In order to solve the disadvantages of Mont-Carlo simulation method used in typical uncertainty analysis, this paper adopted a new method-probabilistic collocation method (PCM) to analyze quantitative uncertainties of...
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In order to solve the disadvantages of Mont-Carlo simulation method used in typical uncertainty analysis, this paper adopted a new method-probabilistic collocation method (PCM) to analyze quantitative uncertainties of dynamic load proportion in dynamic simulation and stability analysis. A case study-New England 10-machine 39-bus system, verified the practicability and validity of the proposed method for uncertainty analysis in dynamic simulation. The results showed that the uncertainties in load composition at buses which are close to the fault site and at the buses that have heavy loads, have strong effects on transient stability, while some load buses that have heavy loads, is little far from the fault site, still have stronger effects on transient stability. It is concluded that the proposed method could directly describe the desired output as a polynomial of parameters. Consequently, the probability distribution of the response could be acquired by probability density function of parameters and much fewer simulations.
An improved differential variance bacterial colony chemotaxis (DVBCC) algorithm was presented for the urban power network substation planning. Bacterial colony chemotaxis (BCC) algorithm improves the speed of converge...
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An improved differential variance bacterial colony chemotaxis (DVBCC) algorithm was presented for the urban power network substation planning. Bacterial colony chemotaxis (BCC) algorithm improves the speed of convergence compared with bacterial chemotaxis (BC) algorithm through the introduction of perception in bacterial colony, and also increases the possibility of a local optimum. DVBCC adopts adaptive control perception scope according to colony' distribution condition, at the same time adds differential variance operator in order to increase the variety of bacterial colony and improves its robust and global optima searching capability. In this paper completed economy of substation optimization planning of 110 kV and 220 kV voltage grade in urban power network was taken as objective function, and factors of geographical effect was considered. The results indicated that DVBCC algorithm outperforms BCC and particle swarm optimization (PSO) algorithms in solving substation planning problem and the proposed model has good economy and practicability.
It is of great importance to study the dynamic behavior of distributed generation (DG), which might affect the fault level and protectionsystem of distribution network greatly. In this paper, the transient stability ...
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It is of great importance to study the dynamic behavior of distributed generation (DG), which might affect the fault level and protectionsystem of distribution network greatly. In this paper, the transient stability of asynchronous type of DG is comprehensively analyzed. The critical shedding time and corresponding slip of DG are calculated. It is pointed out that the fault clearing time of existing relays cannot guarantee DG operates stable when a fault occurs in distribution network. The countermeasures to low down the possibility of instability of DG are suggested. Finally, case studies are carried out using PSCAD to demonstrate the viewpoint of this paper.
This paper proposes a fault classification scheme for transmission lines based on spectrum of fault component. First it analyses the spectrum of fault component, then the characters of power frequency and nature frequ...
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This paper proposes a fault classification scheme for transmission lines based on spectrum of fault component. First it analyses the spectrum of fault component, then the characters of power frequency and nature frequencies in two data windows are used to identify fault type and fault phase respectively. The scheme performance was proven using ATP/EMTP simulations in a 500-kV powersystem considering different fault types and fault locations. The results show that the scheme works quickly and is not impacted by harmonics and the DC offset. It is also not sensitive to sampling rate and fault inception angle.
When faults occur in transmission lines, the high frequency signals are caused by fault generated traveling waves and the spectrum is a series of harmonic in frequency domain. This paper utilizes lumped and distribute...
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When faults occur in transmission lines, the high frequency signals are caused by fault generated traveling waves and the spectrum is a series of harmonic in frequency domain. This paper utilizes lumped and distributed parameter models to express transmission lines respectively, analyzes the character of nature frequencies. Different influencing factors including different fault conditions, source impedance, bus capacitance, series compensated capacitance and shunt reactor are discussed in this paper. The results have been proven by ATP procedure in a typical 500- Kv power transmission line.
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