Innocent Kamwa

Assessment of Two Methods to Select Wide-Area Signals for Power System Damping Control

In this paper, two different approaches are applied to the Hydro-Quebec network in order to select the most effective signals to damp inter-area oscillations. The damping is obtained by static var compensator (SVC) and synchronous condenser (SC) modulation. The robustness analysis, the simulations, and statistical results show, unambiguously, that in the case of wide-area signals, the geometric approach is more reliable and useful than the residues approach. In fact, this study shows that the best robustness and performances are always obtained with the stabilizer configuration using the signals recommended by the geometric approach. In addition, the results confirm that wide-area control is more effective than local control for damping inter-area oscillations.

Active-power stabilizers for multimachine power systems: challenges and prospects

The problem of stabilizing a bulk power system by modulating controllable active loads is investigated. With todays advances in power distribution and home automation, fibre optic communications and networking, such a scheme for improving the reliability of bulk power supply is increasingly attractive. After developing a generic model for active load-modulation studies, time domain modal analysis is applied to a three-machine-nine-bus system in order to assess quantitatively its responsiveness with respect to controller location and observed response signals. This structural analysis shows that proportional control is unsatisfactory and may artificially restrict the economic benefits of active-load modulation. By contrast, using the bus voltage and frequency as input signals, combined with suitable dynamic compensators, yields a fully decentralized, two-loop load stabilizer able to add damping to all grid modes in the sample power system. Finally, placement and sizing issues are considered and preliminary observations based on transient stability studies are made.

Data translation and order reduction for turbine-generator models used in network studies

This paper develops suitable procedures for translating high-order networks into conventional stability constants. The approach is computer-oriented and imposes no restriction on the number of equivalent damper windings per axis. Optimum order reduction is used to demonstrate that second-order networks have a bandwidth limited to between 1 and 5 Hz while third-order models may extend this bandwidth beyond 100 Hz. The latter are therefore mandatory for subsynchronous resonance and harmonic studies. In the course of this investigation, the need for a precise definition of the so-called stability constants arises and it is concluded that only a second-order standstill frequency response (SSFR)-based model yields constants that are consistent with the latest, short-circuit test bound, IEEE standard definitions.

Simulation-based investigation of optimal demand-side primary frequency regulation

Many electric power utilities, such as Hydro-Quebec, are capacity limited despite having enormous energy surpluses. When demand and supply fluctuate, frequency control guaranties that the nominal network frequency remains constant. Frequency control can be applied on generation as well as demand side. This paper investigates the application of optimal demand side frequency based load control (OLC) for primary frequency regulation by comparing the performance of OLC and turbine governor action. This kind of comparison may be of interest to power utilities seeking improvement of the efficiency of their power plants. Also presented is a comparative investigation of the effects of choosing different disutility functions on OLC performance with respect to nadir and steady state error. The detailed simulation is performed using SimPowerSystems (SPS) toolbox, in phasor mode, on the IEEE 39-bus New England test system.

Advanced Modeling of a Synchronous Generator Under Line-Switching and Load-Rejection Tests for Isolated Grid Applications

This paper deals with an efficient method behind the analysis of a saturated synchronous generator (SG) under line-switching and load-rejection tests for islanded networks. This novel approach is based on a SG and ( P,V,Q) load-equivalent combined state-space model. Full and partial load-rejection tests and line-switching tests are explored. The k -factor cross-saturation theory of SG is applied to account for the saturation phenomenon in the proposed model. The paper also attempts to point out the duality between line-switching and load-rejection tests. As the best alternative to the load-rejection test, the line-switching test is simple and more suitable, providing easy steady-state conditions (zero armature currents and rotor angle). Consequently, there is no need for rotor angle positioning when performing the test. Comparisons between simulation results and actual data obtained from a four-pole 1.5-kVA, 208-V, 60-Hz laboratory machine show the effectiveness of the proposed SG stator decrement tests analysis framework.

Impact of Causality on Performance of Phasor Measurement Unit Algorithms

Most existing phasor measurement units (PMUs) are noncausal PMUs and they compensate for the group delay in PMU applications by shifting time stamps, which may result in high latency that will impair performance of PMU applications. This paper presents causal PMUs to reduce the group delay caused latency without shifting time stamps, and studies the impact of causality on performance of PMU algorithms. The paper first analyzes how causal and noncausal PMUs compensate for the group delay caused by digital filters and it is found that causal PMUs normally reduce latency by the group delay, whereas noncausal PMU will not. Then, the impact of causality on performance of PMU algorithms is investigated and analyzed by using the Hydro Quebec Research Institute (IREQ) PMU model and the IEEE PMU model. Finally, the simulation results carried out on two test systems highlight the difference between the causal method and the noncausal method under fault conditions in realistic multimachine setups.