• Energy Research

This paper proposes a hybrid machine learning method for the reliability evaluation of integrated power-gas systems (IPGS) under the uncertain component failure probability distributions. The Random Forest (RF) method is designed to select important features to solve the insufficient quantity of data and the curse of dimensionality problems. The Extreme Gradient Boosting (XGBoost) regression algorithm is developed to quantify the relationship between the uncertain parameters and reliability metrics. Moreover, a ten-fold cross-validation method is employed to further improve the accuracy of the regression model. Simulation results on three test systems show that the proposed method can achieve high accuracy for the reliability evaluation.

It is a crucial yet challenging task to ensure commercial load resilience during high-impact, low-frequency extreme events. In this paper, a novel safe reinforcement learning (SRL)-based resilient proactive scheduling strategy is proposed for commercial buildings (CBs) subject to extreme weather events. It deploys the correlation between different CB components with demand response capabilities to maximize the customer comfort levels while minimizing the energy reserve cost. It also develops an SRL-based algorithm by combining deep-Q-network and conditional-value-at-risk methods to handle the uncertainties in the extreme weather events such that the impact from extreme epochs in the learning process is greatly mitigated. As a result, an optimum control decision can be derived that targets proactive scheduling goals, where exploration and exploitation are considered simultaneously. Extensive simulation results show that the proposed SRL-based proactive scheduling decisions can ensure the resilience of a commercial building while maintaining comprehensive comfort levels for the occupants. In this paper, a novel safe reinforcement learning-based resilient proactive scheduling strategy is proposed for commercial buildings subject to extreme weather events.

Energy flow calculation is a fundamental problem of the integrated power and gas system (IPGS) operation and planning. However, the nonlinear gas flow model introduces major challenges to the energy flow calculation. In this paper, we propose a tractably convex optimization model to solve the energy flow problem in IPGSs. It is demonstrated that the proposed optimization model has the same optimal solution as the original nonlinear steady energy flow model. Also, piecewise linearization is adopted to tightly linearize the nonlinear objective function of the model, which transforms the formulated convex optimization into a linear program one. Thus, the computation complexity of the proposed energy flow model is significantly reduced as compared with the existing methods. In addition, the proposed model can be extended to probabilistic energy flow estimation. Extensive case studies are conducted to validate the effectiveness of the proposed energy flow model using three IPGSs.

This study presents a summary of green building research through a bibliometric approach. A total of 2980 articles published in 2000–2016 were reviewed and analyzed. The results indicated that gree...

Global sensitivity analysis (GSA) of distribution system with respect to stochastic PV and load variations plays an important role in designing optimal voltage control schemes. This paper proposes a data-driven framework for GSA of distribution system. In particular, two representative surrogate modeling-based approaches are developed, including the traditional Gaussian process-based and the analysis of variance (ANOVA) kernel ones. The key idea is to develop a surrogate model that captures the hidden global relationship between voltage and real and reactive power injections from the historical data. With the surrogate model, the Sobol indices can be conveniently calculated through either the sampling-based method or the analytical method to assess the global sensitivity of voltage to variations of load and PV power injections. The sampling-based method estimates the Sobol indices using Monte Carlo simulations while the analytical method calculates them by resorting to the ANOVA expansion framework. Comparison results with other model-based GSA methods on the unbalanced three-phase IEEE 37-bus and 123-bus distribution systems show that the proposed framework can achieve much higher computational efficiency with negligible loss of accuracy. The results on a real 240-bus distribution system using actual smart meter data further validate the feasibility and scalability of the proposed framework.

Today’s power distribution system is changing to a power-electronics-enabled distribution system, especially with the increasing penetration of distributed energy resources (DERs). To monitor and manage those electronic devices and DERs at the grid edge, the advanced metering infrastructure (AMI) with two-way communications presents great potential. At present, extensive research explores the upstream communication from smart meters to electric utilities (e.g., meter reading) but few examine the downstream communication from the utilities to smart meters (e.g., meter pinging). This paper discusses the AMI two-way communication and its recent industrial practice in the U.S., especially for applying the smart meter pinging functionality to monitor grid-edge devices and DERs. This paper then develops the two-way communication model and the network calculus method to quantify the impact of the two-way communication on the AMI network. In the end, the proposed method is validated with ns-3 simulation using the modified 13-node test feeder and real-world feeder systems.

This article investigates the voltage monitoring and control feature for smart meters and identifies the impact of this feature on both power distribution and communication systems. Regarding the voltage monitoring, a cosimulation platform is developed using GridLAB-D and ns-3 to analyze the impact of adding voltage measurements to smart meter readings and assess the mitigation strategies for reducing timeout errors and packet drops of smart meter data. Regarding the voltage control, a new voltage stability control scheme is developed, which applies the voltage stability margin as the control objective, instead of the traditional voltage magnitude. The proposed control scheme makes use of existing advanced metering infrastructure and distributed energy resources (DERs), requiring small marginal costs. It is indicated that integrating the voltage monitoring and control feature, smart meters could enable the voltage stability issues being solved at end-user sides, i.e., the “last-mile” segment. It is also implied that the new feature could support the coordination of the local and system-level voltage controls using both customer-owned and utility-scale DERs.

This paper develops a new response-surface-based Bayesian inference approach for power system dynamic parameter estimation of a decentralized generator using phasor-measurement-unit measurement. The response surface for the decentralized generator model is formulated through a polynomial-chaos-based surrogate. This surrogate allows us to efficiently evaluate the time-consuming dynamic solver at parameter values through a polynomial-based reduced-order representation. In addition, a polynomial-chaos-based analysis of variance is performed to screen out model parameters while ensuring system observability. In dealing with sampling the non-Gaussian posterior distribution for the parameters, the Metropolis-Hastings sampler is adopted. The simulations conducted in the New England system under different system events show that the proposed method can achieve a speedup factor of two orders or magnitude compared with the traditional method while providing full probabilistic distribution of model parameters and achieving the same level of accuracy.

In distribution networks, N-1 contingencies are the main threats to load loss. To reduce the risk from power system threats, the energy storage (ES) can be applied to mitigate the load loss after the N-1 contingencies. However, for a given number of ESs, different location of ESs may have different mitigation results. This article first proposes a bi-level optimization model to find an optimal allocation of ESs for distribution networks, where the upper-level model is to minimize the total risk of all N-1 contingencies and the lower-level model is to compute the load loss for each contingency. Then, the proposed bilevel model is equivalently transformed into a single-level model using Karush–Kuhn–Tucker conditions. The simulation results on two test systems show the effectiveness of the proposed model.