The study deals with the application of energy storage connected to the low‐voltage microgrid by coupling inverter for simultaneous energy management and ancillary services that include the compensation of power quality disturbances. The usefulness of storage equipment as a solution to various problems that accompany microgrid development is discussed. Then, the idea is presented to join different tasks the storage can perform in one application. Control algorithm is presented for storage inverter, which enables storage unit to be charged or discharged according to assumed schedule and to contribute to power quality improvement through the compensation of reactive power, current harmonics and unbalance. Effectiveness of compensation is examined on the simulation model of test microgrid. Moreover, the results of tests performed in real test microgrid configured in the Laboratory of Distributed Generation at the Lodz University of Technology are presented in the study.

The paper deals with compensation of frequently time-variable loads by means of STATCOM controllers. An arc furnace is considered as a heavily distributing load. The STATCOM system was used to ensure good power quality at the point of common coupling. For analysis of the system performance, the PSCAD/EMTDC programme was applied. Simulation models of the load and two types of STATCOM controllers, 12-pulse and 24-pulse, are discussed in the paper. A PSCAD model of a measurement block is also proposed for power quality assessment. Some results of simulation are presented, which show the compensation effectiveness.

As a result of many factors, including the European Union's aim to increase the share of electrical energy from renewable sources, the number of distributed-generation (DG) devices in Europe is significantly increasing. Increasing numbers of DG units may cause problems with power quality (PQ). In this paper, a PQ-management algorithm is presented that reduces or even solves this problem in low-voltage grids. This algorithm will be implemented as one of several software modules in a system for distributed power operation and PQ management in low-voltage grids. PQ management in this context means maintaining PQ within prescribed limits by optimizing the control of generators, storage units, and controllable loads. Significant advantages of the presented approach are that the algorithm is universal and that it adapts its control variables automatically. Therefore, a detailed analysis of the grid in advance is not necessary. Furthermore, local PQ control of distributed resources can work autonomously and continuously without triggering by external signals, which is advantageous in the case of loss of communications. Various simulations to validate the effectiveness and stable operation of the algorithm were performed and results presented that show a marked improvement in PQ.

The paper presents capabilities of DSTATCOM systems used to improve power quality (PQ) in low voltage (LV) grids with distributed energy resources (DERs). For the case study a typical rural network has been selected in which, on one hand DER installing is the most probable and on the other hand, integration process may cause the biggest problems. Selected single-phase DERs of varying power are connected into the network which introduce PQ disturbances such as voltage variations, harmonics and asymmetry. To mitigate deviations in power quality DSTATCOM compensator operating in current control mode has been applied. Models of the network together with the selected DERs and compensator system have been developed in the PSCAD/EMTDC environment. Simulation has been performed for the analysis of the network performance and the assessment of compensation effectiveness. The possibility of using the DSTATCOM operating in voltage control mode for reducing voltage dips coming from the supplying network has also been studied. Control circuits have been designed for these two modes of operation. Description of the study network, their element models and some selected results of simulation are presented in the paper.

This paper presents the use of real-time digital simulator (RTDS) and hardware-in-the-loop (HIL) methods for the validation of an energy management system designed for real low-voltage (LV) distribution networks with a high penetration of renewable energy sources. The system is used to address voltage violations and current overloading issues and allows the network operator to maintain safe and controllable network operations. The applied control strategy and the system software were verified by means of simulations. In this paper, the next stage of system validation using the HIL method is presented. A testbed was designed and developed to test the operation of prototype controllers of the system in flexible and reproducible conditions before installing them in the network. The presented testing platform not only includes the LV network simulator with the power amplifiers needed for closed-loop setup but also additional elements of a real network to which the system is dedicated, i.e., the advanced metering infrastructure, photovoltaic source, and energy storage inverters and load devices. Furthermore, the real cellular network of the distribution network operator is used in the communication between the controllers. In addition, the article contains discussions on communication issues, including limitations related to selected protocols. Finally, examples of the experimental validation of the controller prototypes are presented.