Xue-Bo Chen

Decomposition and decentralized control of systems with multi-overlapping structure

This paper considers decomposition and decentralized control of systems with multi-overlapping structure. It is demonstrated, using the inclusion principle, how the systems with longitudinal, loop and radial topologies can be expanded, and how the results can be used for designing controllers under information structure constraints. The proposed methodology is applied to automatic generation control (AGC) of an electric power system.

Overlapping decentralized approach to automation generation control of multi-area power systems

An overlapping decentralized control scheme is presented and applied to automatic generation control (AGC) for multi-area power systems. Based on the inclusion principle, the system is first decomposed in the expanded space as a group of pair-wise subsystems (areas). Then, the decentralized controllers designed, by standard linear quadratic (LQ) control laws are implemented in each pair-wise subsystem. Finally, the overlapping decentralized controller is obtained by coordinating and contracting the pair-wise decentralized controllers from the expanded space to the original space, preserving the inclusion conditions. When applied to AGC of a four-area power system, the proposed methodology not only guarantees AGC qualities, but also increases the system reliability with respect to a wide variety of structured perturbations. Simulation results illustrate the effectiveness of the presented approach both in the general case of information structure constraints and in the cases when some pairs of subsystems are disconnected by unpredicted faults.

Dual inclusion principle for overlapping interconnected systems

Restriction and aggregation are two dual inclusion conditions, which are revealed in the research field of inclusion principle for state space descriptions of overlapping interconnected systems. An input-state-output dual inclusion principle is proposed for linear time invariant systems and their dual systems, with the focus on restriction and aggregation in duality for direct contraction of control laws and state observers. In these two special inclusion cases, dual relationships of restriction and aggregation inclusion conditions are formulated between an original system and its dual system. Overlapping decentralized controller design problems are considered within the framework of the dual inclusion principle. It is shown that, if dual inclusion is satisfied, in the same type of expansions (restriction or aggregation) for both original system and its dual system, direct contraction can be applied to designed control laws or state observers from the expansion to the original space, while dual information of designed state observer or control laws can be contracted directly from the dual expansion to the dual original space.

Stochastic Inclusion Principle Applied to Decentralized Overlapping Suboptimal LQG Control

Abstract An input-state-outpufc inclusion principle for linear stochastic systems is proposed, with the focus on restriction and aggregation conditions for estimators and dynamic controllers. Particular attention is paid to the inclusion with respect to the optimal LQG (Linear - Quadratic - Gaussian) design. General results are applied to decentralized overlapping control of large-scale interconnected systems. Possibilities of the proposed methodology are illustrated on a model of electric power systems; the obtained decentralized dynamic controller is superior to the standard solutions.

Pair-wise decomposition and coordinated control of complex systems

Pair-wise decomposition and coordinated control for complex interconnected systems with any information structure constraints are proposed in this paper. Based on the inclusion principle, a permuted inclusion principle is presented to expand the system into an expanded space, from which a recurrent reverse order of pair-wise subsystems is extracted. By a standard LQ control, pair-wise controllers can be designed to stabilize and coordinate the pair-wise subsystems. According to these controllers, a coordinated compensator of subsystem interconnections is introduced in order to obtain a coordination-based controller for the expanded system. Therefore, a coordinated controller of the system can be contracted from the expanded space under the conditions of the inclusion principle. Moreover, a sufficient condition of connective stability for the system is also proved by the Lyapunov function and M-matrix. A main advantage of the proposed decomposition and control is that it allows any variation of information structure constraints of the system, especially the increase and decrease of subsystem numbers. Finally, the effectiveness of the proposed methodology is demonstrated by an application of automatic generation control to a four-area electric power system.

Improved Artificial Moment Method for Decentralized Local Path Planning of Multirobots

An improved artificial moment method is presented for the decentralized local path planning of multirobots. In the method, coordinated and repulsive moments are improved with critical factors, attractive moments are improved with attractive angles, and attractive points are also improved. Furthermore, a modified method for robots final motion vectors is proposed, where if a robot has dangerous companions, then the superposition principle may not be used for its final motion vector. For these improvements, the artificial moment method can be used safely in complicated dynamical environments while high quality solutions are often yielded. Simulation results indicate that the improved method is effective.

DECENTRALIZED H∞ DESIGN OF AUTOMATIC GENERATION CONTROL

Abstract An H ∞ decentralized design is proposed for automatic generation control (AGC) of multi-area overlapping interconnected power systems. To derive the resulting controller, the Inclusion Principle and LMI algorithms are discussed in the H ∞ framework for the original and expanded systems. Taking a two-area overlapping interconnected power system AGC as an example, a simulation of responses to load step disturbances is used to illustrate the performance of the new H ∞ decentralized AGC design.

A Decentralized Method Using Artificial Moments for Multi-Robot Path-Planning

For the local path-planning of multi-robots, a decentralized method is presented where each robot plans its own path in the following steps for each iteration. Firstly, an optimal way representative point (OWRpoint) is obtained for guiding the robot to move along a shorter path. Then, the robot moves a step under the control of its own motion controller, which is designed based on artificial moments. In the motion controller, attractive and repulsive moments are used to move robots closer to their OWRpoints and away from obstacles, while coordinated moments are used to resolve the conflicts between robots. Two simulations are given to test the method and the results indicate that the method is valuable as it meets the requirements of the real-time property while optimizing the performance measure of each robot: namely, the path travelled to reach the robots target.

Decentralized Automatic Generation Control Based on a Stochastic Inclusion Principle

Abstract An inclusion principle is formulated for stochastic systems, including the LQG optimal design. The obtained results are applied to decentralized overlapping control of large-scale interconnected systems. The efficiency of the proposed methodology is illustrated on a stochastic model of automatic generation control (AGC) for interconnected electric power systems. Two types of decentralized sub-optimal dynamic controllers consisting of state estimators and feedback gains are proposed. An extensive analysis of both steady-state and transient regimes under a variety of operating conditions shows the efficiency of the proposed AGC scheme.