Voltage Stability Assessment Of Power System With Statcom Device

The power systems in the world generally have got into the age with the character of great network, high voltages and large capacity generators for last 30 years. Since the reality that a number of power must be transmitted to the distant centers of load with the high voltage lines, the stress on the power systems become heavier and heavier, so that the power systems runs on the edge of stability limit. In the meantime, a series of blackout which were derived by voltage instability, happen in some great networks around the world. These accidents brought a long time blackout with the character of expanding widely and great loss, for this reason, the problem of voltage stability become the focus in the people's eyes.As a member of FACTS family, STATCOM with the capacity of flexible absorbing or generating reactive power is significant for preventing voltage instability, so that STATCOM is paid attention to more and more in the study of voltage stability. It is necessary for the safety of power systems to assess the effect of STATCOM about voltage stability, and reflect the distance with the voltage collapse point.In this thesis, the differential algebraic equation (DAE) set were reduced to represent the transient stability model and steady state model with beginning from the principle scheme of STATCOM.On the base of STATCOM which were reduced, voltage stability index(VSM) reduced from continuation power flow, VCPI, sensitivity index, eigenvalue structure analysis were used to evaluate the effect of STATCOM about voltage stability, and reflect the distance with the voltage collapse point in the method of comparing with or without STATCOM in the bus or installing the STATCOM in the different buses.On the test case of WSCC 3 machines 9 buses, a number of calculation and analysis were performed using these four indices and STATCOM models. It is concluded that the effect of voltage stability indices were improved distinctly in the allocation with STATCOM in the buses than the allocation without STATCOM. It is proved that STATCOM can effectually improve voltage stability of power system. Voltage stability index(VSM) reduced from continuation power flow, is a new index claimed in this thesis. VSM can assess the different effect when STATCOM of different capacity installed in different buses.