A Multi-Area Architecture for Real-Time Feedback-Based Optimization of Distribution Grids

TL;DR

The paper tackles the challenge of fast, privacy-preserving coordination of DERs across large, multi-stakeholder distribution networks to support the Transmission Network. It proposes a hierarchical, multi-area feedback-based control framework where local controllers operate within connected control areas and exchange only adjacent-area information, enabling rapid tracking of TSO setpoints while respecting voltage, current, and boundary constraints. A rigorous stability analysis links closed-loop equilibria to a generalized Nash equilibrium and provides explicit conditions for global exponential stability, along with a practical tuning procedure for sampling, costs, tolerances, and dual gains. Case studies on a 5-bus feeder, IEEE-123, and IEEE-8500 demonstrate scalability and performance, showing that the multi-area approach closely matches centralized performance while preserving privacy and reducing communication and computation burdens. The work offers a viable pathway for real-time, large-scale DER coordination that supports TN-DN interactions without compromising stakeholder privacy or operational boundaries.

Abstract

A challenge in transmission-distribution coordination is how to quickly and reliably coordinate Distributed Energy Resources (DERs) across large multi-stakeholder Distribution Networks (DNs) to support the Transmission Network (TN), while ensuring operational constraints continue to be met within the DN. Here we propose a hierarchical feedback-based control architecture for coordination of DERs in DNs, enabling the DN to quickly respond to power set-point requests from the Transmission System Operator (TSO) while maintaining local DN constraints. Our scheme allows for multiple independently-managed areas within the DN to optimize their local resources while coordinating to support the TN, and while maintaining data privacy; the only required inter-area communication is between physically adjacent areas within the DN control hierarchy. We conduct a rigorous stability analysis, establishing intuitive conditions for closed-loop stability, and provide detailed tuning recommendations. The proposal is validated via case studies on multiple feeders, including IEEE-123 and IEEE-8500, using a custom MATLAB-based application which integrates with OpenDSS. The simulation results show that the proposed structure is highly scalable and can quickly coordinate DERs in response to TSO commands, while responding to local disturbances within the DN and maintaining DN operational limits.

Figures (11)

• Figure 1: Single-feeder DN internal structure. Zoomed-in areas illustrate the interaction between parent and child areas within a feeder. Red and green boxes illustrate the visibility of each LC over the local infrastructure and resources, including local grid measurements ($\rm \mathbf{v,i,p,q}$) and local DER.
• Figure 2: Three phase 5-Bus feeder circuit.
• Figure 3: 5-Bus feeder step-tracking with disturbance response. (a) Tracking of $\Delta \mathrm{p}_0$ with 1CA (blue) and 2CA (orange) configurations. (b) DER active power responses. Dashed lines corresponds to single-area (1CA) while solid lines corresponds to multi-area ($2 \rm{CAs}_{\rm LPF-PID}$). (1CA: $a_{\lambda,1},a_{\mu,1} = 5\times 10^3$, 2CA: $a_{\lambda,2}, a_{\mu,2} = 5\times 10^3$, 2${\rm \acp{CA}}_{\rm LPF-PID}$: $\alpha_1, \alpha_2 = 0.003$, $a_{\lambda,2}, a_{\mu,2} = 5\times 10^3$)
• Figure 4: 5-Bus feeder step-tracking with disturbance voltage and current control with 1CA (blue) and 2CA (orange) configurations. Dashed lines corresponds to regular constraints on voltage ($\overline{\mathbf{v}} = 1.05$ p.u.) and $135$A current limit.
• Figure 5: IEEE-123 bus feeder with six control areas.

Theorems & Definitions (1)

• Theorem 4.1: Closed-Loop Stability