Receding-horizon control of distributed Generation to correct voltage or thermal violations and track desired schedules

Abstract

This paper presents a real-time, centralized control system acting on the active and reactive powers of distributed generators when the network experiences voltage and/or thermal limits violation. The control resorts on multi-step receding-horizon optimization. The objective is to minimize the deviations of Dispersed Generation Units (DGU) active and reactive powers from reference values. The reactive power corrections have priority over the active ones. Furthermore, the formulation is such that DGU powers are restored to their desired schedule as soon as operating conditions allow doing so. Three modes of operation of the proposed controller are presented, involving dispatchable units as well as DGUs operated to track maximum power output. The effectiveness of the proposed control is illustrated through detailed simulations of a 75-bus, 11-kV system hosting 22 DGUs.

Combined Local and Centralized Voltage Control in Active Distribution Networks

“…The prediction is initialized with the last gathered measurements V m (k) and I m (k). S QQ and S V Q are sensitivity matrices whose derivation is detailed in the next section, and S IQ relates the branch current variation to DGU reactive power changes [12]. The use of the static transition model (6) and (7) is justified by the fast response of the power electronics based DGUs compared to the MPC sampling time.…”

“…Alternatively, each column of the matrix can be computed by running a power flow calculation with one DGU reactive power slightly modified, and dividing the bus voltage variations by the reactive power variation considered (see e.g. [12] for more details). By substituting (16) in (15), one easily obtains:…”

“…The controller coordinates the power outputs of DGUs and the voltage set-point of the transformer Load Tap Changer (LTC) to smoothly bring the unacceptable voltages inside specified bounds. The approach was extended in [11], [12] to handle congestions and track desired production schedules.…”

Voltage profile correction in distribution grids combining single- and two-level controllers

“…Alternatively, each column of the matrix can be computed by running a power flow calculation with one DGU reactive power slightly modified, and dividing the bus voltage variations by the reactive power variation considered (see e.g. [11] for more details). By substituting (15) in (14), one easily obtains:…”

“…3 is embedded in the differential-algebraic model of the DGU unit, while the centralized controller acts at discrete times only. The quadratic programming problem (4)(5)(6)(7)(8)(9)(10)(11) is solved with the VE17AD package from Harwell [16].…”