Rui Bo

Interval Power Flow Analysis Using Linear Relaxation and Optimality-Based Bounds Tightening (OBBT) Methods

With increasingly large scale of intermittent and non-dispatchable resources being integrated into power systems, the power flow problem presents greater uncertainty. In order to obtain the upper and lower bounds of power flow solutions including voltage magnitudes, voltage angles and line flows, Cartesian coordinates-based power flow is utilized in this paper. A quadratically constrained quadratic programming (QCQP) model is then established to formulate the interval power flow problem. This non-convex QCQP model is relaxed to linear programming problem by introducing convex and concave enclosures of the original feasible region. To improve the solutions bounds while still encompassing the true interval solution, optimality-based bounds tightening (OBBT) method is employed to find a better outer hull of the feasible region. Numerical results on IEEE 9-bus, 30-bus, 57-bus, and 118-bus test systems validate the effectiveness of the proposed method.

A Novel Market Simulation Methodology on Hydro Storage

This paper presents a novel methodology to simulate the economic performance of hydro storage systems in the day-ahead (DA) and real-time (RT) markets. A detailed hydro storage system model is proposed to capture the unique characteristics of hydro storage units. A unique RT market bidding method named Tiered Bidding is proposed to represent the RT market offers of hydro storage units. In order to accurately represent the way hydro storage systems participate in the RT market, four hydro system RT bidding strategies are proposed and evaluated. The proposed methodology is applied to the Eastern Interconnection system to evaluate the economic benefits of Manitoba Hydros market participation in MISOs RT energy and ancillary services market.

A Robust Two-Level Coordinated Static Voltage Security Region for Centrally Integrated Wind Farms

Integration of centralized wind farms may induce cascading tripping incidents, which brings about critical challenges to secure operation of power grid. One of the major risks is the lack of coordinated voltage/reactive power control for multiple wind farms. Therefore, a robust master-slave two-level coordinated static voltage security region (VSR) is proposed in this paper, along with detailed modeling of the network topology and wind farms to achieve coordination among wind farms. The slave VSR on the wind-farm-side is designed to guarantee the operation of each wind unit within a secure range in order to protect wind units from serious over-voltage and low-voltage problems, whereas the master system-wide VSR aims to coordinate centralized wind farms to ensure security both under normal operating conditions and N - 1 contingency conditions. Furthermore, a hierarchically iterative coordination method is introduced to compute the voltage security range of each wind farm through the iteration process. A modified six-bus system with two wind farms, a real system from Northern China, and a large system with 972 wind units are studied, and results verify the effectiveness of the proposed two-level VSR and the hierarchically iterative coordination method.

LODF-based transmission solution screening method in economic transmission planning

Economic transmission planning aims at identifying transmission solutions that reduce system congestion and increase market efficiency. The resulting economic benefits can be quantified by intensive simulations. However, with the rapid increase in the number of transmission proposals for evaluation, the computational requirements may become prohibitive, and therefore it is beneficial to develop an effective and computational efficient screening methodology to screen transmission solutions and identify promising ones for further refinement and full economic evaluation. This paper discusses the guiding principles of an ideal transmission screening method, and proposes a novel LODF-based screening approach. The proposed heuristic yet effective method has been successfully applied in MISO economic transmission planning studies. A case study is provided to demonstrate its effectiveness and advantages.

Novel congested flowgate grouping methods in economic transmission planning

In value-based transmission planning, market efficiency and associated economic benefits can be achieved from transmission solutions that reduce system congestions. However, to accrue the most value and design the most cost effective transmission solution, it is beneficial to understand the interactions among congested flowgates and strategically address selected congestion issues collectively rather than individually. This paper proposes two methods to group congested flowgates: correlation method and OTDF method. The proposed methods have been applied to MISO system to demonstrate the effectiveness. Simulation results using hourly chronological SCUC/SCED tool show that up to 370% synergic benefits can be realized if identified groups of congested flowgates are addressed at the same time. The proposed methods are easy to implement, and have great computational advantage over existing simulation-based exhaustive method.

Impact of Negative Reactance on Definiteness of B-Matrix and Feasibility of DC Power Flow

This paper reports an essential phenomenon on the existence of “negative reactance” in practical power system models. The negative reactance issue is important, as it could affect the definiteness of the <inline-formula> <tex-math notation=LaTeX>

GPU-Accelerated Batch-ACPF Solution for N-1 Static Security Analysis

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Optimal Selection of Phase Shifting Transformer Adjustment in Optimal Power Flow

</tex-math></inline-formula> admittance matrix of power networks and the feasibility of dc power flow. With the graph theory, the <inline-formula> <tex-math notation=LaTeX>

Negative Reactance Impacts on the Eigenvalues of the Jacobian Matrix in Power Flow and Type-1 Low-Voltage Power-Flow Solutions

{B}

Quantifying the benefits of energy and ancillary services market

</tex-math></inline-formula> matrix can be treated as a Laplacian matrix. Several theorems and corollaries are given with proof to study the definiteness of the Laplacian matrix with negative weights. Based upon these theorems, the exploration in this paper demonstrates that the negative reactance may even result in “physical dis-connectivity” and make the linear system singular, so that the dc power flow will be infeasible. The results on several test systems show that the location and value of the negative reactance affect the dc power flow feasibility.