Compact Electric Power System for Fusion Reactor
The issue of the Tokamak fusion reactor is its large area occupied by its power supply, which is about half of the total building area for the International Thermonuclear Experimental Reactor (ITER), together with the compatibility between the site grid and Tokamak loads during the plasma operation period. ITER is now implemented with Tokamak, which requires about 1 GVar reactive power to compensate its power system for superconducting magnets where about 0.2 GVar is transferred from France Electrical Power Network, the other 0.75 GVar is generated by the system of reactive power compensation and harmonic filtering, the standard VSC configuration. ITER can experimentally generate 500-MW fusion thermal power in 400 s long pulse mode. It could only generate about 500 MW/3 = 167 MWe active electric power if it is to be configured with pressured water reactor due to the fact that it is only about 1/3 conversion efficiency from thermal energy to electric energy. For such fusion machine, the requirement for reactive power is much larger than the active power it generates. Based on this requirement, one efficiency and compact pulsed synchronous generator is suggested for this purpose. It can generate not only the fundamental reactive power to compensate and stabilize the power network with low internal impedance but also the active power for outputting power to the network with exciting controller of the generator. Due to its two purposes in one device configuration, it becomes compact and reliable by being implemented in the design of future fusion power plant for demonstration. Some consideration has been done to the special low impedance synchronous generator, which is intended for the concept design of Chinese Fusion Engineering Testing Reactor, targeting the compact electric power system for superconducting Tokamak fusion reactor.
A ride-through power structure for CFETR
The China fusion engineering test reactor (CFETR) is an ITER-like tokamak system for fusion energy development. It could output 50-200 MW fusion power in phase I for demonstrating power generation with complete structure of fusion power plant, and 1 GW output power can be expected in phase II. Its ITER-like HV substation receives power from the 500 kV transmission grid for powering its pulsed power electric network (PPEN) and steady-state electric power network (SSEN). This paper describes the concept design of the electric power system, with emphasis on its turbine generator implemented with flexible doubly fed induction generator (DFIG). DFIG has ride through ability during the plasma-off period. Its capability diagram is configured to analyze its operation range. Similar to ITER, the CFETR also requires about 1 GVar reactive power to be compensated. Based on this requirement, the generator is expected to generate part of reactive power to compensate and stabilize the local power network.
Two-dimensional gravitational anomalies, Schwinger terms and dispersion relations
Abstract We are dealing with two-dimensional gravitational anomalies, specifically with the Einstein anomaly and the Weyl anomaly, and we show that they are fully determined by dispersion relations independent of any renormalization procedure (or ultraviolet regularization). The origin of the anomalies is the existence of a superconvergence sum rule for the imaginary part of the relevant formfactor. In the zero mass limit the imaginary part of the formfactor approaches a δ-function singularity at zero momentum squared, exhibiting in this way the infrared feature of the gravitational anomalies. We find an equivalence between the dispersive approach and the dimensional regularization procedure. The Schwinger terms appearing in the equal time commutators of the energy momentum tensors can be calculated by the same dispersive method. Although all computations are performed in two dimensions the method is expected to work in higher dimensions too.