Steady‐state security assessment method based on distance to security region boundaries

Abstract

Steady-state security region (SSR) provides a region-wise approach to assess the steady-state security of power systems. Based on the SSR model, we introduce the concept of 'steady-state security distance' (SSD) to provide exact 'quantitative analysis' on the scale of security margins for system operators. Then, mathematical models of SSD are formulated. On this basis, implementation of SSD is discussed towards various uncertainties within the power system operation. As the calculation of SSD is in essence a large-scale non-linear optimisation process, it requires very long computation time, and thus could not be utilised in practical application. In order to enhance the efficiency of computation, a novel algorithm is proposed, which decomposes the complex optimisation process into two steps: active SSR boundary identification and partial constrained solution. The proposed algorithm remarkably cuts the scale of the optimisation model as well as the number of calculations, thus significantly reduces the computation time to meet requirements of assessment towards day ahead and hours ahead generation schedules. In the end, an IEEE-30 bus case and a practical case on a provincial power system are both studied to testify the effectiveness of the proposed model and algorithm.

Model, Characterization, and Analysis of Steady-State Security Region in AC/DC Power System with a Large Amount of Renewable Energy

“…(It can be seen that the linear regression boundaries can replace the original boundary surfaces well from the case study below). For each effective boundary, the critical points are chosen randomly on the boundary surface based on the Equations (1)- (11), and the number of critical points is selected as 4-6 times the dimensions of the steady-state security region (the undetermined coefficients). According to the chosen critical points, the multiple linear regression is completed according to the regression Equation (20).…”

“…U s1k − U s2k = I s R ij (11) The subscripts i, j denote AC bus i and AC bus j, and the subscript k denotes converter k. P i , Q i , U i , and θ ij respectively denote the nodal injected active power, nodal injected reactive power, nodal voltage amplitude, and the difference of nodal phase angle. j i denotes node j which is connected to node i (including node i).…”

Yardstick competition-based comprehensive assessment approach of power system security with intermittent generation integration

“…Mohammed Benidris et al consider three probabilistic transient stability indices to assess system robustness against dynamic contingencies and to account for system instability in computing reliability indices . Sijie J. Chen et al introduce the concept of “steady‐state security distance” to provide exact quantitative analysis on the scale of security margins for system operators and provide the system operators a global view on overall security margins including recognizing the critical uncertainties affecting system security and their impacts on security margins, and identifying the most fragile components within the systems . Wu, Lan et al propose a reliable method to evaluate the stationary distribution probability based on the Markov chain method .…”

Information extraction from effective descriptor variables in reconstruction of power system security region by considering correlation between loads

“…Saric and Stankovic proposed a multidimensional ellipsoids oriented computational approach to approximate feasible sets of security region . Chen et al proposed an algorithm that simplifies the complexity of the optimization process to enhance the computational efficiency of steady‐state security distance . In Fisch et al and Sun et al, power system security region has been identified by considering N‐k contingencies, uncertainty in power system loads, and soft security limits.…”