Wideband Harmonic Voltage Compensator Technology for Enhancing the Stability of Multi-Paralleled Inverter Systems

Description

With the increasing awareness of environmental protection, the popularity of distributed power generation systems (DPGSs) at the point of utilization of a single entity or part of a microgrid operating in parallel with or independent of the utility grid is growing. For example, the Hong Kong Government has progressively implemented government-led renewable energy measures, such as the introduction of different incentive schemes and policies, and large-scale renewable energy projects. A feed-in tariff policy scheme has recently been introduced to provide incentives for individuals and non-government bodies to invest in renewable energy.A typical distributed power generation system converts the electrical energy generated by the microsource, such as wind turbine and photovoltaics, into a DC form with a regulated voltage. The DC power is then converted by a grid-connected inverter (GCI) into a form of AC power for the utility grid. DPGSs have several potential advantages over traditional centralized power systems, as they provide clean power, reduce carbon emissions, improve energy efficiency, optimize asset utilization. However, with the increasing penetration of DPGS, the number of GCIs connected in parallel will greatly increase. The correlation and coupling among inverters, linear and nonlinear loads, and utility grid will form a complex high-order electric network. More importantly, uncertain impedance changes at the point of common coupling (PCC) make the grid voltage sensitive to fluctuations in the power generated. The system may exhibit multiple types of resonances that can be identified as internal resonance caused by the local filter in the inverters, parallel resonance with other paralleled inverters, and series resonance with the utility grid. The resonance issue in multi-paralleled GCIs has become a challenge for DPGS reliability and the utility grid operation stability and has attracted great attention from researchers in academia and industries.The project aims to solve the above problems. A wideband harmonic voltage compensator technology that can enhance the stability of systems with multi-paralleled GCIs and linear and nonlinear loads will be studied. In addition, the compensator will have an evolutionary computation-based algorithm integrated for extracting some critical parameters to describe, monitor, and predict the performance characteristics and stability of the system. This project will be in collaboration with the government department - Electrical and Mechanical Services Department. The research team will be arranged to evaluate the performance of the developed single- and three-phase prototypes in government offices with grid-connected buildingintegrated hybrid renewable energy systems.