Maximum allowable distributed generation with consideration of fault ride through requirement and utility protection system

Abstract

Distribution systems are changing from one-source supplying structure into multi-source supplying structure with participations of distributed generations. The strong increase in number of renewable-based generating plants, with the advanced control technology, impulses their role in power systems. Using a package of an asynchronous generator along with an inverter to synchronize the output with the power system is an upward tendency for generating units in these plants. Such generating unit is known as an inverter-based distributed generation. Besides, many combined heat and power plants using synchronous generators are still used in power systems and named synchronous machine-based distributed generation. From distributed generation’s owner perspectives, the renewable energy should be exploited; hence, the installation capacity of the distributed generation is expected to be as large as possible. However, the installation of distributed generation may violate system operating limits such as substation and line capacities, voltage limits and causes other impacts dealing with protection system operation. This thesis considers typical problems such as system operating limits, reach reduction of utility relay, and fault ride through requirement from distribution system operators in order to maximize distributed generation’s installation. Fault responses of the inverter-based distributed generation to a fault in the network are characterized with consideration of fault ride through requirement of the distribution system operators. Based on the obtained characteristics, a new model of the inverter-based distributed generation is proposed. This model is convenient for an adaptive fault calculation algorithm which is to estimate fault currents in the system for setting and checking the operation of protection system. This fault calculation algorithm is then employed by an algorithm proposed for maximizing distributed generation. The IEEE 34 Node Test Feeder is then used to illustrate the effectiveness of the algorithm in determining the maximum distributed generation installed in this system.