• Energy Research

Abstract In the present paper, methods of finding the criterial value for the Lyapunov function are considered. A new method is described which eliminates generation of all possible starting points. The criterial starting point has been determined by finding the minimum cut set for a certain network representing transfer synchronizing powers of generators. The proposed method is faster than techniques published so far.

Abstract In the present paper, methods of finding the criterial value for the Lyapunov function are considered. A new method is described which eliminates generation of all possible starting points. The criterial starting point has been determined by finding the minimum cut set for a certain network representing transfer synchronizing powers of generators. The proposed method is faster than techniques published so far.

This paper proposes a new event-based logic of the breaker failure protection to improve power system transient stability by shortening the total clearing time of extreme contingencies involving circuit breaker failures. Stability improvement is achieved by using dual-timer protection with shorter safety margin for multi-phase faults close to the power plant and longer safety margin for remote multi-phase faults and single-phase faults. The use of the output signal obtained for a short safety margin depends on how the substation is configured. In the breaker-and-a-half configuration, this output signal is used to speed up the opening of all adjacent circuit breakers. In substations with the dual (or triple) busbar configuration the output signal obtained with a short safety margin is used to speed up the busbar splitting. A case study was performed for a real large-scale power system. Simulation results confirmed the advantages of the proposed logic. Breaker failure protection with the proposed logic has been implemented in a substation of a large power plant.

This paper proposes a new event-based logic of the breaker failure protection to improve power system transient stability by shortening the total clearing time of extreme contingencies involving circuit breaker failures. Stability improvement is achieved by using dual-timer protection with shorter safety margin for multi-phase faults close to the power plant and longer safety margin for remote multi-phase faults and single-phase faults. The use of the output signal obtained for a short safety margin depends on how the substation is configured. In the breaker-and-a-half configuration, this output signal is used to speed up the opening of all adjacent circuit breakers. In substations with the dual (or triple) busbar configuration the output signal obtained with a short safety margin is used to speed up the busbar splitting. A case study was performed for a real large-scale power system. Simulation results confirmed the advantages of the proposed logic. Breaker failure protection with the proposed logic has been implemented in a substation of a large power plant.

Transmission expansion planning requires static and dynamic analyses. Planning criteria include the selection of contingencies consisting of faults and their clearing, performance standards, transmission system adjustments, and corrective action plan. Performance standards relating to power system dynamics mainly concern the voltage ride through and transient angle stability i.e. retaining synchronism after the occurrence of the contingencies mentioned. The selection of planning contingencies, for which performance standards must be complied with, is important in terms of capital expenditures in transmission network expansion and secure power system operation. This paper discusses planning contingencies accepted by various transmission network operators worldwide and describes a set of planning contingencies proposed by the authors.

Transmission expansion planning requires static and dynamic analyses. Planning criteria include the selection of contingencies consisting of faults and their clearing, performance standards, transmission system adjustments, and corrective action plan. Performance standards relating to power system dynamics mainly concern the voltage ride through and transient angle stability i.e. retaining synchronism after the occurrence of the contingencies mentioned. The selection of planning contingencies, for which performance standards must be complied with, is important in terms of capital expenditures in transmission network expansion and secure power system operation. This paper discusses planning contingencies accepted by various transmission network operators worldwide and describes a set of planning contingencies proposed by the authors.

This paper describes new structures for stability-enhancing excitation controllers designed using a nonlinear multi-machine system model and Lyapunov's direct method. Two control structures are presented: a hierarchical structure In which the AVR is the master controller and the PSS the slave controller and a traditional structure in which the PSS constitutes a supplementary loop to the main AVR. Both controllers are shown to be robust, as the damping they introduce into the system is insensitive to changes in both the system topology/parameters and the pattern of network flows. Each individual controller contributes positively to the overall system damping with no undesirable interaction between controllers. These features should allow a decentralized approach to the design of the AVR+PSS. Such a design approach is compatible with the new competitive market structures and should result in savings on commissioning costs. Simulation results for a multi-machine power system are presented that confirm the above and show that the two control structures are very effective in damping both local and inter-area power swings