Application of solid state switching devices to electronic load governing of micro hydro generators

A three phase, electronic load governor (ELG) has been developed. Based on the binary load technique, it uses a ballast load to compensate for any torque imbalance on the shaft system. The ballast load which is applied to the generator is connected via solid state relays incorporating a zero voltage switching circuit producing virtually no RF interference. They are controlled by a microprocessor and the input is optically isolated from the output circuit. The authors give an introduction to the design requirements for micro hydroelectric generating schemes and to the load governing principles involved. They present a brief background of the development of the ELG and goes on to describe the ballast load switching circuits. The solid state switches are described and their operational performance discussed. They describe a computer model which simulates the transient frequency performacne of the system under the control of the ELG