New Energy-Saving Measures for High-Frequency High-Voltage Power Supplies in Electrostatic Precipitators

The electrostatic precipitator (ESP) system is the core equipment for industrial flue gas purification, and its energy consumption mainly comes from the high-frequency high-voltage power supply (accounting for more than 70% of the total energy consumption of the ESP system). Traditional ESP power supplies have problems such as low light-load efficiency and serious energy waste. Therefore, realizing the energy-saving upgrade of high-frequency high-voltage power supplies through the optimization of control strategies, innovation of topological structures, and application of energy recovery technologies has become a key direction to reduce industrial energy consumption and promote the greening of environmental protection equipment.
The optimization of control strategy is the core means for energy saving of high-frequency high-voltage power supplies in ESPs. The dust removal efficiency of ESP is closely related to the output voltage and current of the power supply: when the dust concentration in the flue gas is high, it is necessary to increase the output voltage to enhance the electric field strength and capture more dust; when the dust concentration is low, if the high-voltage output is still maintained, it will lead to energy waste. The leading energy-saving scheme adopts the "dust concentration-power supply parameter" adaptive control strategy: a laser dust concentration sensor is installed at the inlet of the ESP electric field to collect dust concentration data in real time. After the data is processed by the edge computing module, the optimal voltage and current commands are output. The control algorithm adopts fuzzy PID control. Compared with traditional PID control, fuzzy PID can quickly adjust the output parameters according to the change of dust concentration (the dynamic response time is shortened to 100μs), avoiding energy waste caused by voltage overshoot. For example, when the dust concentration decreases from 50mg/m³ to 10mg/m³, the power supply output voltage can be reduced from 65kV to 45kV, and the current from 100mA to 30mA. At this time, the power supply efficiency is still maintained above 90%, saving 25%~30% more energy than traditional constant voltage control.
The innovation of topological structure improves the full-load efficiency of the power supply. During the operation of the high-frequency high-voltage power supply for ESP, the load rate fluctuates between 20%~100% with the change of dust concentration. The traditional topological structure (such as single-stage full bridge) has a significant decrease in efficiency at light load (only 75%~80%), leading to a large amount of energy loss. The energy-saving scheme adopts an interleaved parallel Boost + LLC resonant composite topology: the interleaved parallel Boost circuit reduces the number of working units at light load (such as 2 units in parallel, only 1 unit works at light load) to reduce switching loss. The LLC resonant topology realizes zero-voltage switching (ZVS) of switching tubes in the full load range, reducing switching loss by 60%. Through the composite topology, the power supply efficiency is increased to 88% at 20% light load and 94% at rated load, which is 8%~10% higher than the average full-load efficiency of traditional topologies. Taking the ESP system of a 300MW thermal power unit as an example, after adopting the composite topology power supply, the annual power consumption is reduced from 1.2 million kWh to 0.9 million kWh, saving 600,000 yuan in annual electricity costs (calculated at 0.6 yuan/kWh).
Energy recovery technology realizes the reuse of waste energy. During the ESP process, the electric field will have periodic "spark discharge", at which time the power supply output current increases sharply. The traditional power supply will consume the excess energy through the discharge resistor, resulting in energy waste; at the same time, when the electric field load changes suddenly (such as the dust concentration decreases suddenly), the power supply output power is excessive, which also causes energy waste. The energy-saving scheme introduces an energy recovery circuit: a bidirectional DC/DC converter is connected in parallel on the DC bus side of the power supply. When spark discharge or power surplus occurs, the bidirectional converter feeds the excess energy back to the power grid. To avoid the impact of feedback energy on the power grid, an LC filter circuit is designed at the output end of the converter to control the harmonic content of the feedback current within 5%, complying with the GB/T 14549 standard. In addition, in view of the intermittent working characteristics of ESP (such as the ESP system starts and stops 2~3 times a day in some industrial scenarios), the power supply adopts supercapacitor energy storage technology, which uses the energy stored in the capacitor for the next start-up when shutting down, reducing the power grid energy consumption during start-up. Through energy recovery technology, 10%~15% of the waste energy in the ESP process can be recovered, further improving the energy-saving effect.
Soft switching technology and loss suppression further reduce energy consumption. Switching loss and conduction loss of high-frequency high-voltage power supplies are important components of energy loss. The energy-saving scheme adopts soft switching technology (such as zero-voltage zero-current switching ZVZCS), so that the voltage and current of the switching tube are zero when turning on and off, and the switching loss is close to zero; at the same time, wide-bandgap semiconductor devices (such as SiC MOSFET) are used to replace traditional IGBTs. The on-resistance of SiC devices is only 1/5 of that of IGBTs, the conduction loss is reduced by 80%, and the temperature resistance is better, which can reduce the energy consumption of the heat dissipation system. In addition, in the design of the power transformer, high-frequency low-loss silicon steel sheets (such as 30Q130) are used to reduce iron loss; the windings are connected in parallel with multi-strand enameled wires to reduce copper loss, and the transformer efficiency is increased to 98%.
Through the above new energy-saving measures, the comprehensive energy-saving rate of the high-frequency high-voltage power supply for ESP can reach 25%~40%, which not only reduces the energy consumption cost of industrial enterprises but also reduces carbon emissions (calculated according to thermal power units, each saving 10,000 kWh of electricity can reduce carbon emissions by about 8.5 tons), which is in line with the development demand of environmental protection equipment under the "dual carbon" goal.