Battery storage has been adopted to coordinate with generators in automatic generation control (AGC). In this paper, a control strategy of battery storage involved in secondary frequency regulation is proposed. Through the analysis of the control mode based on area control error signal and the control mode based on area regulation requirement signal in AGC, the integrated control strategy was developed, and the switch timing and the output depth of the battery storage were defined. That is, when the system frequency is deteriorated and the frequency deviation $\vert \Delta f \vert $ is large, according to the fuzzy logic method, the output power of the battery storage will be smoothened on the basis of the state of charge (SOC). When the system frequency is normal, the frequency deviation $\vert \Delta f \vert $ will be small. The remaining frequency regulation capacity of generators can be used to improve the SOC. Furthermore, according to the defined frequency regulation evaluation indexes, MATLAB/Simulink was used to simulate the battery storage coordinating generators for secondary frequency regulation. A typical continuous disturbance was selected in the simulation. The results of the simulation showed that the proposed strategy could enhance the effect of frequency regulation, improve the SOC of the battery storage, and increase the utilization rate of the generator set.

Secondary Frequency Regulation Strategy With Fuzzy Logic Method and Self-Adaptive Modification of State of Charge

Identification of coherent trajectories by modal characteristics and hierarchical agglomerative clustering

The paper describes an algorithm for parameter identification of a dynamic equivalent for an external subsystem, based solely on the available online measurements in boundary buses and branches. Static equivalent part is represented by equivalent impedances from boundary buses (ones that separate the internal and external subsystems) and calculated using the modified (minimum loss) radial, equivalent, and independent method. Parameter identification of synchronous generator (SG)-based equivalent (for predominantly production external areas), dynamic load (DL)-based equivalent (for predominantly load external areas), or (SG + DL)-based equivalent (for mixed external areas) in fictitious buses is performed by Levenberg–Marquardt weighted least-square nonlinear optimization, which minimizes the variances between available online measurements and transient responses of the reduced power system. The IEEE 14-bus and 441-bus real-world test systems are used to illustrate and test the proposed power system equivalent derivation technique.

Data-Driven Dynamic Equivalents for Power System Areas From Boundary Measurements

A hybrid optimization framework for the non-convex economic dispatch problem via meta-heuristic algorithms

This paper discusses the phasor, frequency, and the rate of change of frequency (ROCOF) estimations in Microgrids. This is accomplished using the estimates processed by a real PMU and their comparisons with the digital Cosine filter, adding new metrics for frequency and ROCOF. A real event recorded is employed aiming to estimate the phasor parameters in time-domain signals. A traditional static phasor model algorithm for the digital Cosine filter is taken into account, using a rectangular window lasting two cycles. Both frequency and ROCOF metrics are conceived by drawing an analogy with their estimations if a dynamic phasor model is assumed. The attained results demonstrate that the digital filtering process done by the Cosine filter outperforms the provided estimates by the real PMU and the new metrics suitably track the changes in frequency and ROCOF.

Phasor, frequency and ROCOF measurements in microgrids: A practical approach

This paper addresses the power system model order reduction proposing an optimal formulation for identifying electromechanical modes present in active power flows. The reduced power system preserves the dynamic and physical characteristics of the studied system. The modal identification is achieved by the digital Taylor–Fourier transform, which decomposes an oscillating signal into monocomponents. Then, these ones are embedded into an objective function with the purpose of estimating the equivalent generators’ parameters. Results demonstrate a reduction in the computational burden and the computing time associated with transient stability studies for the preserved system, retaining its steady-state and dynamic conditions.

Jose David Lara-Jimenez

Papers

Dynamic Equivalents by Modal Decomposition of Tie-Line Active Power Flows