A real-time architecture for the identification of faulty magnetic sensors in the JET tokamak
A real-time architecture for the identification of faulty magnetic sensors in the JET tokamak
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DOI：
10.1109/rtc.2012.6418376
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发表时间：
2012-06
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通讯作者：
A. Neto;D. Alves;B. B. Carvalho-B.;G. De Tommasi;R. Felton;H. Fernandes;P. Lomas;F. Maviglia;F. Rimini;F. Sartori;A. Stephen;D. Valcárcel;L. Zabeo
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作者：
A. Neto;D. Alves;B. B. Carvalho-B.;G. De Tommasi;R. Felton;H. Fernandes;P. Lomas;F. Maviglia;F. Rimini;F. Sartori;A. Stephen;D. Valcárcel;L. Zabeo
在托卡马克中，等离子体边界的准确估计对于最大限度地提高聚变性能至关重要，也是保证装置物理完整性的第一道防线。特别是，如果过度暴露在高等离子体热负荷下，第一壁组件可能会严重损坏。计算等离子体几何形状和相关参数的最常用方法是基于一组不同类型的磁传感器。利用这些信息，实时等离子体平衡代码推断出通量图，并计算出等离子体边界的形状和几何形状及其到已知参考点（例如第一壁）的距离。这些是一个或多个控制器的输入，能够根据预定义的请求对形状和轨迹进行操作。根据设备的不同，估计边界距离的误差通常必须小于1厘米，这意味着磁测量本身的误差非常小。此外，产生的等离子体和周围磁场的不对称性会产生局部形状变形，可能导致等离子体几何形状控制不稳定。JET托卡马克最近升级为一种新的、热强度较低的全金属壁，也被称为iter式壁。目前的形状控制系统使用单一重构算法的输出来驱动等离子体的几何形状，保护系统没有来自等离子体边界重构的输入。这些选择是历史上的，是由于架构、硬件和处理能力的限制。利用新型多核系统和JET实时网络的鲁棒性，提出了一种用于JET托卡马克磁测量故障实时识别的分布式体系结构。除了检测短路和开环等简单故障外，该系统还将线圈位置的预期测量值与实际测量值进行比较，从而产生置信度值。使用来自多个环形分布位置的传感器的几个磁重建可以并行运行，从而允许投票或平均方案选择。最后，任何故障预警都可以直接馈送到实时保护序列器系统，该系统的主要功能是协调JET第一壁的保护。
In a tokamak, the accurate estimation of the plasma boundary is essential to maximise the fusion performance and is also the first line of defence for the physical integrity of the device. In particular, the first wall components might get severely damaged if over-exposed to a high plasma thermal load. The most common approach to calculate the plasma geometry and related parameters is based in a large set of different types of magnetic sensors. Using this information, real-time plasma equilibrium codes infer a flux map and calculate the shape and geometry of the plasma boundary and its distance to a known reference (e.g. first wall). These are inputs to one or more controllers capable of acting on the shape and trajectory based in pre-defined requests. Depending on the device, the error of the estimated boundary distance must usually be less than 1 centimetre, which translates into very small errors on the magnetic measurement itself. Moreover, asymmetries in the plasma generated and surrounding magnetic fields can produce local shape deformations potentially leading to an unstable control of the plasma geometry. The JET tokamak was recently upgraded to a new and less thermally robust all-metal wall, also known as the ITER-like wall. Currently the shape controller system uses the output of a single reconstruction algorithm to drive the plasma geometry and the protection systems have no input from the plasma boundary reconstruction. These choices are historical and were due to architectural, hardware and processing power limitations. Taking advantage of new multi-core systems and of the already proved robustness of the JET real-time network, this paper proposes a distributed architecture for the real-time identification of faults in the magnetic measurements of the JET tokamak. Besides detecting simple faults, such as short-circuits and open-loops, the system compares the expected measurement at the coil location and the real measurement, producing a confidence value. Several magnetic reconstructions, using sensors from multiple toroidally distributed locations, can run in parallel, allowing for a voting or averaging scheme selection. Finally, any fault warnings can be directly fed to the real-time protection sequencer system, whose main function is to coordinate the protection of the JET's first wall.