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Research On Power System Cascading Outages And Its Relative Issues

Posted on:2009-07-14Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y YuFull Text:PDF
GTID:1102360272977845Subject:Power system and its automation
Abstract/Summary:PDF Full Text Request
The insecurity and instability problems will certainly cause enormous losses and catastrophic results for modern power systems with the feature of extra high voltage and long-distance transmission lines, large capacity generators, cross-regional inter-connections and huge inter-area power exchanges. Therefore, studies on the power system security and stability have been received much attention for a long time. Several blackouts in the past few years fully reveal the vulnerability of large inter-connection power system. It's important and urgent to research on the reason, evolvement and preventive measures of blackouts. Many works have been done and some of cascading outage model, such as OPA, CASCADE and Hidden Failures were present by the researchers. However, these cascading outage models are imprecise and some factors, such as time-domain dynamic characteristic of electric components are not included. To solve these problems, dynamic cascading outage models are present in this thesis and self-organized criticality(SOC) of power system is analysed. Contributions are summarized as follows:1. A cascading outage model with its stochastic counterparts are present for cascading failure investigation. Stochastic factors associated with generator frequency relay, u.f. load shedding and breaker tripping time, etc. are explicitly modeled. Using a Monte Carlo simulation tool, the risk of frequency-induced cascading failures is assessed. The influences of relevant factors on statistic characteristic of power system cascading failures, such as frequency primary regulation, AGC (spinning reserve), the size of initial disturbance and u.f. load shedding schemes, are also analyzed. The results presented demonstrate interesting values of the model in identifying the factors that contribute to cascading failures and blackouts.2. A cascading outage model based on dynamic simulation has been developed and analyzed in this work together with its stochastic counterpart. The factors, such as stochastic characters of generator frequency/voltage protection, under-frequency/under-voltage protection, over-excitation, overload, short circuit and its tripping time, are considered. The model captures the fundamental dynamic characteristics of power system and its validity and accuracy for studying system cascading are confirmed based on PSS/E with Monte Carlo simulation. The results show the existence of the power law with critical points. When the critical point is exceeded, the outage size and its probability rise rapidly and the power law characteristic is changed. Critical points provide helpful information for blackout prevention.3. Based on dynamic cascading outage model, the influence of simulation parmaters, such as under-freqency/voltage load shedding, load components, primary regulation and tie-line power flow on power system SOC, critical points and blackouts probability is analysed. Some suggestions for blackout prevention is present hereby.4. The maximum penetration level of distributed generation under different anti-islanding methods is calculated using dynamic simulation. The frequency/voltage protection, under-frequency/volage load shedding and capacity constrains of transmission lines are fully consided. The influency of anti-landing methods on maximum peretration level of DG is discussed. These provide theoretical basis for analyzing the influence of DG on cascading outages.5. A cascading outages dynamic model with DG comprised is present. Influency of Different penetration levels of DG and aiti-landing methods on cascading outages and its SOC is analysed. The simulation results reveal that probability of blackout changes periodically with increasing of DG penetration level and main generator shutdown. The maximum penetration level of DG is discussed based on blackout probability.
Keywords/Search Tags:Time domain dynamic simulation, Cascading outages, Critical points, Distribution generation, Maximum penetration level
PDF Full Text Request
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