ESTIMATION OF ENERGY EFFICIENCY OF ACTIVE POWER FILTERS FOR POWER SUPPLY SYSTEMS USED IN THE NORTHERN AREAS

Abstract

The relevance of the research is caused by the need of energy efficiency improvement at the power supply systems used in the northern areas, where the best part of the mining industry is located. In these regions power supply is provided by diesel generator units, gas-turbine generator units and water power plants. Lack of the centralized electricity and expensive fuel transportation have made the cost of the electrical energy ten times higher than in central regions. Plenty of the nonlinear and reactive loads results in poor power quality, reactive and distortion power losses. In order to minimize the nonlinear and reactive loads influence, active power filters are implemented. Typically, an active power filter is a voltage source inverter operating as a controlled current source. An active power filter installation requires substantial investments and, therefore, economic considerations must be taken into account. This, in its turn requires a comprehensive energy efficiency estimation of the active power filter operation to be done. Currently, there is no any unified approach to estimate the energy efficiency of an active power filter or similar power electronic device as well as no method to estimate its efficiency and possible economic effect of non-active power compensation. All of these makes the development of a mathematical model of the power supply system with an active power filter to be an actual problem. The main aim is energy efficiency improvement in power supply systems of the northern areas by active power filter implementation. Objects: power electron devices intended to electrical energy circulation between them and the grid, such as active power filters, STATCOMs, etc. Methods. In order to achieve the aim of the research, several tasks were formulated. One of them is the mathematical approach to estimate the active power filter energy efficiency. This approach uses calculation based on spectral method and switching functions. The mathematical model is represented in a discrete form. It allows one to calculate all the currents and voltages in the power circuit of the active power filters, its rms and average values. A new approach to calculate the efficiency is proposed. It suggests to set the load active power as the useful power and the one plus the active power filters power losses as the total power. Besides, three new power quality factors are proposed to give an estimation of active power filter effectiveness concerning its influence on apparent power, reactive power and the distortion power. Results. The active power filter energy quality performance is estimated qualitatively and quantitatively. Active power filter’s converter currents are obtained as instantaneous values, rms and average values. Conduction and switching losses are calculated for 2-level and 3-level inverter based on active power filters circuit. New energy quality performance factors are defined as well as the active power filter efficiency. All the results obtained in the mathematical model are verified by the simulation model in Matlab Simulink software.

Keywords

• northern areas power supply
• reactive power compensation
• distortion power compensation
• active power filter mathematical model
• active power filter efficiency calculation