Research on Distribution Network Security Analysis Based on K

The objective of security analysis is to find the weak link of distribution network. The K(N-1+k) criterion based on the characteristics of distribution network was proposed for distribution network security analysis. According to the K(N-1+k) criterion, the electrical devices in the contingency set can be classified into two kinds. The first kind meets the requirement of the K(N-1+k) criterion. The rank preference optimal ordering (RPOO) was proposed to evaluate the damage degree of power system. The second kind does not meet the requirement of the K(N-1+k) criterion, and it is the weak link of distribution network. A numerical experiment shows that the method is efficient and feasible, and the proposed method can provide assistant decision-making for safety precautions

A Straightforward Method for Wide-Area Fault Location on Transmission Networks

Local practices in fault location require measurements from one or more terminals of the faulted line to be available. On the other hand, the nonlinearity of circuit equations associated with wide-area fault location makes their solving process iterative and computationally demanding. This paper proposes a non-iterative method for wide-area fault location by taking advantage of the substitution theorem. Accordingly, a system of equations is constructed which can be easily solved using the linear least-squares method. The distributed-parameter line model is considered to provide a highly accurate estimation. Besides, due to inherent errors of current transformers, the current data is not taken into account to preserve the accuracy. In order to avoid uncertainties in relation with construction of zero-sequence network, just positive- and negative-sequence networks are exploited. Nonetheless, the method still is capable of pinpointing all types of short-circuit faults by using a restricted number of synchronized pre- and post-fault voltage phasors. Numerous simulation studies conducted on the WSCC 9-bus and New England 39-bus test systems verify the effectiveness and applicability of the proposed fault location method, even with limited coverage of synchronized measurements

Operation and restoration of bulk power systems using distributed energy resources and multi-microgrids

The fast-paced and meaningful penetration of distributed energy resources (DERs), such as variable renewable energy sources (RESs), concurrently with the widespread occurrence of natural disasters and man-made threats, has raised several challenges for the modern bulk power systems (BPSs) status quo. Although the DERs are demanding new solutions to ensure adequate stability and security levels, these resources enable significant opportunities to improve multiple BPS perspectives. In this view, seeking to capitalize on these novel features, while aware of the significant changes to BPS outlook, this thesis is focused on developing new methods able to capitalize on modern monitoring infrastructures, DERs and control areas opportunities toward the improvement of BPS operation and stability. Specifically, the thesis focuses on: 1) First, a novel method for the improvement of the static security region (SSR) is proposed based on a new network partitioning algorithm. The proposed algorithm focuses on modern BPS with high penetration of variable RES generation. It divides the BPS into coherence areas according to its criticality mapping, and consequently, areas are adaptively associated with SSRs generators groups. To this end, each bus is assigned a criticality index from the potential energy function, whereas this calculation is based on the data of the wide-area measurement system (WAMS) using phasor measurement unit (PMU); 2) Second, a novel area-based sensitivity index for voltage stability support is proposed, exploring both the network-wide sensitivity and the local characteristics of voltage collapse. The developed index focuses on the determination of the most effective buses for voltage support and their respective capability of increasing the system’s load margin. For this, a novel area-based outlook is developed taking advantage of the new possibilities enabled by BPS distributed controllable resources, such as flexible resources (FRs)

Development of an Adaptive Restoration Tool For a Self-Healing Smart Grid

Large power outages become more commonplace due to the increase in both frequency and strength of natural disasters and cyber-attacks. The outages and blackouts cost American industries and business billions of dollars and jeopardize the lives of hospital patients. The losses can be greatly reduced with a fast, reliable and flexible restoration tool. Fast recovery and successfully adapting to extreme events are critical to build a resilient, and ultimately self-healing power grid. This dissertation is aimed to tackle the challenging task of developing an adaptive restoration decision support system (RDSS). The RDSS determines restoration actions both in planning and real-time phases and adapts to constantly changing system conditions. First, an efficient network partitioning approach is developed to provide initial conditions for RDSS by dividing large outage network into smaller islands. Then, the comprehensive formulation of RDSS integrates different recovery phases into one optimization problem, and encompasses practical constraints including AC power flow, dynamic reserve, and dynamic behaviors of generators and load. Also, a frequency constrained load recovery module is proposed and integrated into the RDSS to determine the optimal location and amount of load pickup. Next, the proposed RDSS is applied to harness renewable energy sources and pumped-storage hydro (PSH) units by addressing the inherent variabilities and uncertainties of renewable and coordinating wind and PSH generators. A two-stage stochastic and robust optimization problem is formulated, and solved by the integer L-shaped and column-and-constraints generation decomposition algorithms. The developed RDSS tool has been tested on the modified IEEE 39-bus and IEEE 57-bus systems under different scenarios. Numerical results demonstrate the effectiveness and efficiency of the proposed RDSS. In case of contingencies or unexpected outages during the restoration process, RDSS can quickly update the restoration plan and adapt to changing system conditions. RDSS is an important step toward a self-healing power grid and its implementation will reduce the recovery time while maintaining system security