Coordination Of Control Actions Research Articles

Three-level coordination in power system stabilization

This paper presents a new methodology for the synthesis of power system stabilizers (PSSs) and speed governors in order to satisfy some recent objectives and constraints imposed by the evolution of large-scale interconnected power systems. As a consequence of the increasing size of these systems, the frequency of some inter-area modes diminishes so much so that these oscillatory phenomena interact with the dynamics of the speed governors. These low-frequency inter-area modes are also more spread (i.e., they involve a larger number of generators) than the other inter-area modes of the system. This two particularities require several supplementary levels of coordination when tuning the PSSs and the governors of the machines involved in these oscillatory phenomena. To ensure this, the synthesis of the aforementioned regulators is done using a new control model which takes into account the key interactions of the dynamics of the power system. It thus allows the coordination of control actions among several generators as well as between the electrical and mechanical paths. This control framework ensures also an optimal trade-off performance/robustness. Validation simulations have been carried out with the Eurostag software on a realistic large-scale model of the interconnected European power system.

Voltage Coordination via Communication in Large-Scale Multi-Area Power Systems. Part I: Principal

This two-part paper deals with the coordination of the control actions in a network of many interacting components, where each component is controlled by independent control agents. As a case study we consider voltage control in large electric power systems, where ever-increasing pressures from the liberalization and globalization of the electricity market has led to partitioning the power system into multiple areas each operated by an independent Transmission System Operator (TSO). Coordination of local control actions taken by those TSOs is a very challenging problem as poorly coordinated operation of TSOs may endanger the power system security by increasing the risk of blackouts. This coordination problem involves many other issues such as communication, abstraction and last but not least optimization. This first part of the paper is devoted to the principals of the coordination control, addressing some of those issues using as a case study the problem of coordination control for avoiding voltage collapse in large-scale multi-area power systems.

Voltage Coordination via Communication in Large-Scale Multi-Area Power Systems. Part II: Simulation Results

This two-part paper deals with the coordination of the control actions in a network of many interacting components, where each component is controlled by independent control agents. As a case study we consider voltage control in large electric power systems where ever-increasing pressures from the liberalization and globalization of the electricity market has led to partitioning the power system into multiple areas each operated by an independent Transmission System Operator (TSO). Coordination of local control actions taken by those TSOs is a very challenging problem as poorly coordinated operation of TSOs may endanger the power system security by increasing the risk of blackouts. This second part of the paper presents simulation results on a 12-bus 3-area test system, using the distributed model predictive control paradigm in order to design a coordinating model-based feedback controller. Coordination requires that each agent has some information on what the future evolution of its power flows to and from its neighbors will be. It will be shown that how the communication between agents can avoid voltage collapse in circumstances where classical uncoordinated controllers fail.

Alleviation of transmission system overloads using fuzzy reasoning

Power flows on a large inter-connected power system must be kept within limits to prevent thermal overloading leading to excessive sagging of lines or over-heating of transformers and cables. Flows must also be limited to prevent transient instability. Such control essentially requires the co-ordination of sources of active power and controls of its flow such as quadrature boosters. This paper describes a new approach to this co-ordination problem which utilises a fuzzy expert system. A set of rules is developed to model operators' decisions based on criteria concerning the extent of a limit violation, the sensitivity of a candidate control device, the margin available at the control device, the cost of the required control move and the maximum number of control settings to be moved. Co-ordination of control actions using fuzzy inference and composition is shown to succeed in resolving conflicts while use of fuzzy cardinality enables effective control devices to be ranked. The work is extended to address the duration of overloads so that actions are taken only as and when needed, the scheduling of preventive actions and the meeting of group constraints.