In this paper, an online data-driven approach is proposed for the detection of low-quality synchrophasor measurements. The proposed method leverages the spatio-temporal similarities among ...multiple-time-instant synchrophasor measurements and formulates the low-quality synchrophasor data as spatio-temporal outliers. A density-based local outlier detection technique is proposed to detect the spatio-temporal outliers. This data-driven approach involves no system modeling information. The detection algorithm can operate under both normal and fault-on system conditions, with fast computation speed suitable for online applications. Case studies on both synthetic and real-world synchrophasor data verify the effectiveness of the proposed approach.
This paper introduces a framework of transient stability assessment for future distribution systems that are comprised of multiple microgrids. Enabled by the advances in power electronics and ...synchrophasor technologies, an angle droop method is introduced for autonomous real power sharing among coupling-operated microgrids. In our previous work, the small-signal stability criterion are derived. It is well-known that only regional transient stability can be established for conventional multi-machine systems interfaced with synchronous generators. In contrast, we show in this paper that asymptotical stability in the large can be achieved if angle droop method is adopted for real power sharing among coupled microgrids. Transient stability criterion is derived by formulating the linear matrix inequality (LMI) version of the Kalman-Yakubovich-Popov (KYP) conditions corresponding to the multi-variable Popov criterion. Numerical studies show the effectiveness of the proposed transient stability assessment framework for future power electronic-interfaced distribution systems.
With the continuing growth of renewable penetration in power systems, it becomes increasingly challenging to manage the operational uncertainty at near-real-time stage via deterministic scheduling ...approaches. This paper explores the necessity, benefits and implementability of applying stochastic programming to security constrained economic dispatch (SCED). We formulate a stochastic look-ahead economic dispatch (LAED-S) model for near-real-time power system operation. A concept of uncertainty responses is introduced to assess the power system economic risk with respect to net load uncertainties. This concept offers the system operator a simple yet effective gauge to decide whether a stochastic approach is more desirable than a deterministic one. For an efficient stochastic dispatch algorithm, an innovative hybrid computing architecture is proposed. It leverages the progressive hedging algorithm and the L-shaped method. Numerical experiments are conducted on a practical 5889-bus system to illustrate the effectiveness of the proposed approach.
This paper studies the fundamental dimensionality of synchrophasor data, and proposes an online application for early event detection using the reduced dimensionality. First, the dimensionality of ...the phasor measurement unit (PMU) data under both normal and abnormal conditions is analyzed. This suggests an extremely low underlying dimensionality despite the large number of the raw measurements. An early event detection algorithm based on the change of core subspaces of the PMU data at the occurrence of an event is proposed. Theoretical justification for the algorithm is provided using linear dynamical system theory. Numerical simulations using both synthetic and realistic PMU data are conducted to validate the proposed algorithm.
This paper studies the online dynamic security assessment (DSA) of future distribution systems in which multiple electrically coupled microgrids are operated as an interconnection. By leveraging the ...highly controllable power-electronics-based interfaces, we propose a novel interface control strategy for desirable load sharing among interconnected microgrids. Under such a control framework, theoretical results on system-wide stability criteria in the sense of Lyapunov are obtained. Potential application of these results for microgrid-based smart distribution system DSA is presented. Minimum information exchange is required among microgrid modules and the distribution system operator, which is a highly desirable feature in future distribution management systems. Numerical studies of a five-microgrid study system designed based on the IEEE 123-node test feeder show the effectiveness of the proposed control strategy and DSA framework.
The increasing penetration of variable and uncertain generation from renewable resources poses a challenge for balancing the power system supply and demand. Violations of this constraint seriously ...impact system reliability and thus carry with them a very high cost. In order to address the issues created by variable generation increased system flexibility is required. System operators are considering modifications to the conventional real-time economic dispatch model to provide improved ramp flexibility. In this paper an operational flexibility metric called lack of ramp probability (LORP) is proposed for the real-time economic dispatch. Further, a two-step robust optimization based framework is introduced to simultaneously guarantee LORP flexibility metric and ensure ramp deliverability in a multi-zonal setting. The proposed framework is illustrated on a 3-zone modified IEEE 73 bus (RTS-96) test system.
This paper presents the formulation and critical assessment of a novel type of demand response (DR) program targeting retail customers (such as small/medium size commercial, industrial, and ...residential customers) who are equipped with smart meters yet still face a flat rate. Enabled by pervasive mobile communication capabilities and smart grid technologies, load serving entities (LSEs) could offer retail customers coupon incentives via near-real-time information networks to induce demand response for a future period of time in anticipation of intermittent generation ramping and/or price spikes. This scheme is referred to as coupon incentive-based demand response (CIDR). In contrast to the real-time pricing or peak load pricing DR programs, CIDR continues to offer a flat rate to retail customers and also provides them with voluntary incentives to induce demand response. Theoretical analysis shows the benefits of the proposed scheme in terms of social welfare, consumer surplus, LSE profit, the robustness of the retail electricity rate, and readiness for implementation. The pros and cons are discussed in comparison with existing DR programs. Numerical illustration is performed based on realistic supply and demand data obtained from the Electric Reliability Council of Texas (ERCOT).
We study the economic impact of a potential class of integrity cyber attacks, named false data injection attacks, on electric power market operations. In particular, we show that with the knowledge ...of the transmission system topology, attackers may circumvent the bad data detection algorithms equipped in today's state estimator. This, in turn, may be leveraged by attackers for consistent financial arbitrage such as virtual bidding at selected pairs of nodes. This paper is a first attempt to formalize the economic impact of malicious data attacks on real-time market operations. We show how an attack could systematically construct a profitable attacking strategy, in the meantime being undetected by the system operator. Such a result is also valuable for the system operators to examine the potential economic loss due to such cyber attack. The potential impact of the false data injection attacks is illustrated on real-time market operations of the IEEE 14-bus system.
We propose a novel statistical wind power forecast framework, which leverages the spatio-temporal correlation in wind speed and direction data among geographically dispersed wind farms. Critical ...assessment of the performance of spatio-temporal wind power forecast is performed using realistic wind farm data from West Texas. It is shown that spatio-temporal wind forecast models are numerically efficient approaches to improving forecast quality. By reducing uncertainties in near-term wind power forecasts, the overall cost benefits on system dispatch can be quantified. We integrate the improved forecast with an advanced robust look-ahead dispatch framework. This integrated forecast and economic dispatch framework is tested in a modified IEEE RTS 24-bus system. Numerical simulation suggests that the overall generation cost can be reduced by up to 6% using a robust look-ahead dispatch coupled with spatio-temporal wind forecast as compared with persistent wind forecast models.
A novel and unusual palladium‐catalyzed 4+2 annulation of cyclopropenes with benzosilacyclobutanes is reported. This reaction occurred through chemoselective Si−C(sp2) bond activation in synergy with ...ring expansion/insertion of cyclopropenes to form new C(sp2)−C(sp3) and Si−C(sp3) bonds. An array of previously elusive bicyclic skeleton with high strain, silabicyclo4.1.0heptanes, were formed in good yields with excellent diastereoselectivity under mild conditions. An asymmetric version of the reaction with a chiral phosphoramidite ligand furnished a variety of chiral bicyclic silaheterocycle derivatives with good enantioselectivity (up to 95.5:4.5 er). Owing to the mild reaction conditions, the good stereoselectivity profile, and the ready availability of the functionalized precursors, this process constitutes a useful and straightforward strategy for the synthesis of densely functionalized silacycles.
When Si−C meets C=C bond activation: Cyclopropenes were functionalized stereoselectively with benzosilacyclobutanes by palladium‐catalyzed Si−C(sp2) bond activation and a ring‐expansion/4+2 annulation sequence to form new C(sp2)−C(sp3) and Si−C(sp3) bonds of silabicyclo4.1.0heptanes. The transformation provided an array of these previously elusive highly strained bicyclic skeletons in good yields with high selectivity (see scheme).
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
PDF
