Negative Results on Deploying Distributed Series Reactance Devices to Improve Power System Robustness Against Cascading Failures
Abstract : Distributed Series Reactances are devices that dynamically increase the impedance of a line to reduce the power ow it carries. This work explores whether widely deploying these devices enhances a power system's robustness against line overload cascading failures. The presence of Distributed Series Reactances may make it less likely that equipped lines would become overloaded by contingencies elsewhere, and so their presence may arrest the propagation of line overloads through a system. However, the ecacy of these devices in this role has not been widely investigated. Likewise, there are few extant methodologies for siting dynamic reactances within the grid to mitigate the propagation of cascades. In this paper, the ability of these devices to arrest the propagation of cascading failures within power grids is investigated. First, a novel dc power ow is formulated, which models dynamic line impedances. A novel methodology is proposed for siting the devices on lines spread throughout the network. With these innovations in hand, the devices eects on cascade propagation are simulated using a sizeable database consisting of multiple load & generation snapshots across eight test networks. No major benecial eect is found, even when 25% of lines are equipped.
? Improving the observability and operational flexibility of the grid could be considered as a smart measure for improving the transmission grid resiliency.
? Different measures are proposed for improving the transmission capacity of existing infrastructure by deploying FACTS or Distributed FACTS devices or line switching.
? All these measures are studied for proposing a smarter and dispatchable transmission grid, extracting more value from existing network, manage congestion and improve transfer capability of the network by controlling the power flow pattern in the grid.
? Thus DSRs could be used for increasing system loadability, altering the power flow pattern in the grid and more utilizing the existing infrastructure.
? This augmented OPF problem is sometimes referred to as the security constrained optimal power flow (SCOPF).
? If the optimal operating point of the ‘intact system’ does not does not satisfy the security constraints, then the objective function is augmented with new penalty terms for each violation and a new optimal operating point may be obtained.
? Another associated problem with employing a shunt capacitor is the possibility of resonance with the line inductances .
? However, problems of resonance between line inductance and the series capacitance, difficulties in fault management, and low reliability of voltage-source converters have restricted their implementation on a large scale.
• Evolutionary algorithms have been proposed for the problem of optimal locating of FACTS devices , with some specific advantages and disadvantages.
• Sensitivity methods were also applied for determining the most influential locations of series FACTS devices .
• Different performance measures are also proposed in the context of infrastructure resilience such as: connectivity loss, power loss, and impact on the population.
• In contrast to inverter based D-FACTS technology, DSRs proposed a reliable solution for power flow control in meshed grids.
• While hardening approaches may be considered for resiliency improvement, an application of a new and cost effective technology is proposed in this paper.
? If the optimal operating point of the ‘intact system’ does not does not satisfy the security constraints, then the objective function is augmented with new penalty terms for each violation and a new optimal operating point may be obtained.
? It should be noted that while OPF can find an optimum, given the degrees of freedom possible in terms of control elements, it may not represent the best performance that is achievable.
? A single component failure can prove to be fatal in the overall performance of the module.
? Further, currently available power electronic components are not suitable for operation in the hostile utility environment.
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