Reactive Power Resources Management in a Voltage Regulation Architecture Based on Decoupling Control

Abstract

The actions for limiting the climate change are significantly affecting the electrical power system. Indeed, the increase in renewable power sources and the progressive shut off of coal-fired power plants are transitioning the generation from a centralized to a decentralized paradigm. The latter may cause issues in a grid that was originally designed taking as granted the presence of several big power plants to be used as actuators for the system control. Considering voltage control, the actual control architecture is based on a hierarchical structure applied to a given set of rigidly subdivided control areas. Although such architecture is currently capable of maintain voltage control on the grid, the increase in converter interfaced generators (due to renewables exploitation) and the decrease of the buses short circuit powers (due to high power plants shut-off) may decrease its effectiveness in the future. To this aim, in this paper a coordinated decoupling voltage control is proposed, capable of using all the available reactive power sources on the grid as actuators. The issue of controlling a system with a variable number of actuators (due to generators connection and disconnection) is taken into account, proposing a suitable solution for avoiding transients during the switch between controllers having different output dimension. A brief discussion about communication (among actuators and controller) performances required for implementing the proposed control in the power system is also given.

Reactive Power Resources Management in a Voltage Regulation Architecture Based on LQRI Control

“…Some of them are based on H∞ [10], other are based on Model Predictive Control [11], and there are even techniques capable of providing anti-windup function for controllers with integral elements [12]. In [13] the technique proposed in [12] has been chosen and improved for a decoupling PI regulator applied to the transmission network SVC. Thus, in this paper the same technique has been selected, and properly modified and improved, for solving the switching issue related to an LQRI control.…”

“…Being the technique here used based on the equality between the two controller outputs, an integral component is required. Differently to what has been done in [13], where the PI controllers where capable of nullify the input error, here additional integrators (marked as Int in Fig. 2) must be added, being the LQRI integral action applied only on the CNs voltage feedback.…”

“…In this paper, a feedback gain equal to 0.1 has been selected using simulations. As stated in [12] and [13], the primary feedback of this bumpless transfer technique double as anti-windup compensators, if saturations are present in the control signals (Fig. 2).…”

Study on the State Feedback Selection and Measurement for the Application of an LQRI Secondary Voltage Regulator to a Transmission System

“…It is relevant to notice that a single RPR can be composed by different generators/sources, which are aggregated, controlled together, and connected to the transmission network in a single point to provide reactive power and SVC ancillary services. To ensure the correct coordination of these varied RPRs as actuators for voltage regulation, new control architectures may be required [3]. In this paper a Linear Quadratic Regulator with Integral action (LQRI) [4] is selected for the SVC on the transmission grid.…”