Small-Signal Stability Analysis for Droop-Controlled Inverter-based Microgrids with Losses and Filtering

An islanded microgrid supplied by multiple distributed energy resources (DERs) often employs droop-control mechanisms for power sharing. Because microgrids do not include inertial elements, and low pass filtering of noisy measurements introduces lags in control, droop-like controllers may pose significant stability concerns. This paper aims to understand the effects of droop-control on the small-signal stability and transient response of the microgrid. Towards this goal, we present a compendium of results on the small-signal stability of droop-controlled inverter-based microgrids with heterogeneous loads, which distinguishes: (1) lossless vs. lossy networks; (2) droop mechanisms with and without filters, and (3) mesh vs. radial network topologies. Small-signal and transient characteristics are also studied using multiple simulation studies on IEEE test system

Dynamic Optimisation For Power Dispatch In Microgrids

The increasing growth of non-dispatchable renewable energy sources (RES) such as solar and wind and the upcoming plug-in electric vehicles (PEVs) makes the secure power dispatch a challenging optimisation. In this paper, a coordinated power dispatch strategy in microgrids with a battery management system is proposed. The power dispatch strategy dynamically fits the power production to the power demand by appropriately dispatching the controllable distributed energy resources (DER). A strategy is presented where an active battery scheduling system includes the load and generation profiles of the microgrid and the electricity prices of the spot market in order to maximise the microgrid revenue

Multi-objective optimization for environomic scheduling in microgrids

Microgrids are small-scale power systems including distributed generation (DG) units, storage devices and controllable loads, and can operate either connected or isolated from the utility grid. Ensuring an efficient, reliable, economic and environmentally friendly microgrid operation, an environomic power dispatch system is needed. In this paper, a formulation of an environomic scheduling approach in microgrids is proposed using multi-objective decision making method. The application aims to fulfill the time-varying energy demand while minimizing the costs and emissions of the internal production and imported energy from the utility grid. Operational constraints such as generator limits, operation and maintenance costs and the intermittency renewable energy sources (RES) will be satisfied. A representative microgrid structure, including measurement data, is studied as an example and some simulation results are presented to demonstrate the performance of the environomic scheduling approach

Pilot project using curtailment to increase the renewable energy share on the distribution network

Going to a green electricity landscape needs to cover not only the cost of the renewable production units, but also the cost for their full integration in the system. Hence, the additional costs of congestion and balancing need to be considered as well. Solving congestion issues by investing in new grid assets can be a costly and time-consuming way to integrate new renewables to the grid. Hence, the Belgian distribution network operator Eandis started a pilot project on wind turbine control where a traditional connection would not have been possible for the wind turbines. This ‘smart’ connection solves congestion issues and allows more renewable energy on the grid. This seems contradictory, but controllability does not necessarily mean curtailing, as discussed in the paper. It signifies an opportunity for better utilizing the grid assets and allowing more green energy production units in the electric power system. This paper discusses the results of the pilot project

Congestion Control Algorithm in Distribution Feeders: Integration in a Distribution Management System

The increasing share of distributed energy resources poses a challenge to the distribution network operator (DNO) to maintain the current availability of the system while limiting the investment costs. Related to this, there is a clear trend in DNOs trying to better monitor their grid by installing a distribution management system (DMS). This DMS enables the DNOs to remotely switch their network or better localize and solve faults. Moreover, the DMS can be used to centrally control the grid assets. Therefore, in this paper, a control strategy is discussed that can be implemented in the DMS for solving current congestion problems posed by the increasing share of renewables in the grid. This control strategy controls wind turbines in order to avoid congestion while mitigating the required investment costs in order to achieve a global cost-efficient solution. Next to the application and objective of the control, the parameter tuning of the control algorithm is discussed