Design of a Control Scheme for Distribution Static Synchronous Compensators with Power-Quality Improvement Capability

Abstract

Electric power systems are among the greatest achievements of the last century. Today, important issues, such as an ever-increasing demand, the flexible and reliable integration of distributed generation or a growth in disturbing loads, must be borne in mind. In this context, smart grids play a key role, allowing better efficiency of power systems. Power electronics provides solutions to the aforementioned matters, since it allows various energy sources to be integrated into smart grids. Nevertheless, the design of the various control schemes that are necessary for the correct operation of the power-electronic interface is a very important issue that must always be taken into consideration. This paper deals with the design of the control system of a distribution static synchronous compensator (DSTATCOM) based on flying-capacitor multilevel converters. The control system is tailored to compensate for both voltage sags by means of reactive-power injection and voltage imbalances caused by unbalanced loads. The design of the overall control is carried out by using the root-locus and frequency-response techniques, improving both the transient response and the steady-state error of the closed-loop system. Simulation results obtained using PSCAD

Harmonic and imbalance voltage mitigation in smart grids: A DSTATCOM based solution

“…which can be approximated by the instantaneous active power p if the losses in the connection filter are disregarded, i.e., p cDC ≈ v d i st d [15].…”

Power Quality Improvement and LVRT Capability Enhancement of Wind Farms by Means of an Inductive Filtering Method

“…Figure 1 shows the ENTSO-E LVRT requirement for grid-connection, where the wind farms are expected to stay connected even when the grid voltage drops down to 0. In summary, the harmonic components, the voltage fluctuation and the LVRT capability are the crucial issues and should be carefully addressed to improve the power quality and increase the operating efficiency of wind farms [12][13][14][15].…”

Control Scheme of a Concentration Photovoltaic Plant with a Hybrid Energy Storage System Connected to the Grid

“…The use of the SRF allows the q component of the grid voltage to be zero and the sinusoidal magnitudes to become DC variables [34]. The following state-variable model of the grid-connected converter is obtained when the SRF is employed [35]: Although the state-variable model (Equation (9)) is coupled, a decoupled equivalent system can be obtained for control purposes, as explained in [34]. Furthermore, if an invariant-power Park's transformation is chosen, the active power, p g , and the reactive power, q g , injected into the grid can be calculated in the SRF as follows:…”

“…This control structure is designed by taking into account the state-space model (Equation (9)), which is coupled, as mentioned in Section 2.4. In order to tackle this problem, the following decoupled model can be achieved after some calculations (see reference [34] for more details):…”