A Novel FPGA-Based Real-Time Simulator for Micro-Grids

2017 Energies  
To meet the requirements of micro-grid real-time simulation, a novel real-time simulator for micro-grids based on Field-Programmable Gate Array (FPGA) and orders (FO-RTDS) is designed. We describe the design idea of the real-time solver and the order generator. Multi-valued parameter prestorage and multi-rate simulation are introduced to reduce the computational pressure. The data scheduling is carried out following the principle of saving the resources and the minimizing the average distance
more » ... tween variables. An example is performed on XC7VX690T-2FFG1761 chip, which proves the novel FO-RTDS method greatly improves the scale of real-time simulation of micro-grids. 2 of 17 simulator (RTDS), and real time lab (RT-LAB), also play a key role in the hardware-in-the-loop real-time simulation [8] [9] [10] . Although there are big differences among the relevant software of these simulation platforms, all their core devices are either central processing unit (CPU) or digital signal processing (DSP), which targets high-speed computing. Due to the limited number of arithmetic logic elements inside the CPU or DSP, cluster methods are commonly used to solve the calculation problem of micro-grid electromagnetic transient real-time simulation. However, the establishment of a micro-grid hard-ware-in-the-loop real time simulation platform on a large scale based on RTDS or RT-LAB requires huge amounts of funding, so it is difficult to promote the real-time simulation platform to the general scientific research institutions and advanced colleges, let alone use it for technical training in the power sector. FPGA, which has an abundant amount of logic, storage and DSP resources, can be used for power system electromagnetic transient real-time simulation. FPGA realizes real time simulation of transmission line using a full frequency-dependent modeling and conventional component model [11] . Wang proposed a computational solution framework aimed at active distribution network based on FPGA and gave the hardware implementation of several key function modules [12, 13] . Multi-FPGA electromagnetic transient real-time simulation is studied for large-scale power system [14] . The hardware circuits in these references are designed on the basis of the simulation objects, which can minimize the simulation time, but this requires the programmers to have high FPGA programming capabilities and power system expertise. A real-time digital simulator based on FPGA and orders is designed and an order generator is proposed [15] , providing electrical engineers with a general beginner's all-purpose symbolic instruction code (BASIC) programming ability so they can design new simulation applications. FO-RTDS has broken the design concept of converting the simulation object into hardware, which provides a new idea to realize the electromagnetic transient real-time simulation of power system based on FPGA. Each input of arithmetic logic unit in FO-RTDS is equipped with a read controller and each output of arithmetic logic units is equipped with a write controller and a buffer channel. The buffer channel consists of registers which can be read and written from any position. The controller based on order can effectively improve the flexibility of arithmetic and logic operations, but it requires a large number of logical and storage resources. In the process of building FO-RTDS, the logic resources or storage resources may be used up fast, but a lot of DSP resources still remain, which makes the computing ability of FO-RTDS not be very high. Although multi-valued parameter prestorage algorithms and multi-rate simulation algorithms can effectively reduce the amount of calculation, they cannot be achieved in FO-RTDS. Directed acyclic graph (DAG) is used to describe the relationship among the computational tasks in FO-RTDS and a list scheduling algorithm that takes resource constraints into account is used to achieve task scheduling, but the data interactions between microprocessor cores need to be specified in the form of computational tasks in the simulation script. Based on the characteristics of FPGA resources and micro-grid simulation, we design a real-time solver with the ability of parallel computing, multi-valued parameter pre-storage algorithm and real-time solver of multi-rate simulation algorithm. At the same time, we propose an order generator, which has the ability of auto scheduling, following the working principle of real-time solver. The hardware core of the simulation platform−real-time solver is described in Section 2, focusing on the design thought of micro core, data interaction and multi-valued parameter prestorage. Section 3 describes the software core of the simulation platform−order generator, focusing on script design, task scheduling, data scheduling and other key issues. Section 4 presents the functional test of the real-time solver, which verifies the high efficiency of the real-time solver's computing ability. A case is studied in Section 4, which verifies the accuracy of the real-time solver. Some experience got in the process of designing real-time solver and order generator is given in Section 5. (No. 51477114).
doi:10.3390/en10081239 fatcat:n3zf73adsvgm3n7nczsy6fuyuu