Load Monitoring CEC/LMTF Load Research Program

This white paper addresses the needs, options, current practices of load monitoring. Recommendations on load monitoring applications and future directions are also presented

Maximum loadability and voltage stability in power systems

This paper discusses several of the practical and theoretical issues associated with the dynamic vs. static issues of voltage problems. It focuses mainly on the issues of maximum loadability and the avoidance of non-physical models. It concludes with the proposition that static analysis normally produces optimistic upper bounds on practical questions about loadability. Realistic bounds are obtained by a small disturbance analysis and even better with transient large disturbance analysis

目次

This paper introduces the concept of transient algebraic circuits for power system dynamic modelling. The circuits are an exact representation of synchronous machine and R-L network/load dynamics. Approximate circuits are systematically derived to produce reduced-order slow models which capture frequency dependence

Optimization Strategies for the Vulnerability Analysis of the Electric Power Grid

Identifying small groups of lines, whose removal would cause a severe blackout, is critical for the secure operation of the electric power grid. We show how power grid vulnerability analysis can be studied as a mixed integer nonlinear programming (MINLP) problem. Our analysis reveals a special structure in the formulation that can be exploited to avoid nonlinearity and approximate the original problem as a pure combinatorial problem. The key new observation behind our analysis is the correspondence between the Jacobian matrix (a representation of the feasibility boundary of the equations that describe the flow of power in the network) and the Laplacian matrix in spectral graph theory (a representation of the graph of the power grid). The reduced combinatorial problem is known as the network inhibition problem, for which we present a mixed integer linear programming formulation. Our experiments on benchmark power grids show that the reduced combinatorial model provides an accurate approximation, to enable vulnerability analyses of real-sized problems with more than 10,000 power lines

Dynamic aspects of voltage/power characteristics [multimachine power systems]

The authors investigate the dynamic aspects of operation on a typical voltage/power curve. They discuss multiple stable equilibrium points in the context of small signal stability. A single machine example supplying different types of voltage-dependent loads is examined. A multimachine power system is also studied. Examples include a discussion on multiple stable operating points and the effects of different load characteristics

Existence of solutions for the network/load equations in power systems

Virtually all power-system analysis algorithms require the solution of a network/load model. During a numerical simulation of medium and long term dynamic events, this model is solved at every timestep. In all cases it is important that there exists a solution to the model. In this paper we study the quasistatic network/load models for use in steady-state and dynamic power-system analyses and present a set of sufficient conditions which ensures that the network/load model is solvable for voltages and currents