In order to expand the simulation scale of the real-time digital solver based on FPGA (FRTDS, FPGA: field-programmable gate array), the power system modeling process is optimized. The multi-valued parameter method is used to represent the external characteristics of the equipment. The methods of addressing the equivalent admittance and voltage coefficient of the interval unit are discussed in detail. The serial degree of the simulation script is effectively reduced. The disadvantageous effects of asymmetric elements and nonlinear elements on node elimination are analyzed. The elimination order of nodes is determined according to the minimum estimate of the execution time of the simulation script. According to the proposed method to reduce the serial degree and calculation time of the simulation script, software for generating an electromagnetic transient simulation script for power systems is developed. The effectiveness of the software is verified by an example.

Considering the rational use of field programmable gate array (FPGA) resources, this paper proposes a new FPGA-based real-time digital solver (FRTDS) for power system simulation. Based on the relationship between the number of computing components, the operating frequency, and the pipeline length, the best selection principle is given. By analyzing the implementation method of the Multi-Port Read/Write Circuit, the computing formula of the Look-Up-Table (LUT) consumption was derived. Given the excessive use of LUTs in the original computing components, the computing components were assembled in a single typical arithmetic expression of the power system simulation program, as the basic computing formula was characterized by a subset of the typical computing formula and multiple uses of the same variable. Data communication between different computing components was realized by using Multi-Port Input Circuits that share some outputs of read controller, and Multi-Port Output Circuits, which share some outputs of computing cores. According to the test results of original FRTDS and new FRTDS, it was found that the solution proposed in this paper had a shorter ideal simulation time and a higher parallel computing capability, which was very suitable for real-time digital simulation of power systems.

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A field-programmable gate array (FPGA)-based digital solver for real-time electromechanical transient simulation is designed in this paper. The solving process for a device or sub-network in an electromechanical transient simulation is packaged into the orders in soft function solvers. The orders are reused by soft function solvers that are invoked by microprocessor cores. The data exchange between the microprocessor cores and soft function solvers is enhanced through explicit and implicit channels. The orders of the microprocessor cores are stored in the synchronous dynamic random access memory on the FPGA board, which solves the problem of insufficient storage space for the orders in electromechanical transient simulation. A real-time digital solver for electromechanical transient simulation, whose feasibility is verified by a simulation of part of the power system in East China, is successfully constructed by applying a small number of microprocessor cores and multiple soft function solvers.

With the increasing penetration of wind power generation, the frequency regulation burden on conventional synchronous generators has become heavier, as the rotor speed of doubly-fed induction generator (DFIG) is decoupled with the system frequency. As the frequency regulation capability of wind farms is an urgent appeal, the inertia control of DFIG has been studied by many researchers and the energy storage (ES) system has been installed in wind farms to respond to frequency deviation with doubly-fed induction generators (DFIGs). In view of the high allocation and maintenance cost of the ES system, the capacity allocation scheme of the ES system—especially for fast-frequency response—is proposed in this paper. The capacity allocation principle was to make the wind farm possess the same potential inertial energy as that of synchronous generators set with equal rated power. After the capacity of the ES system was defined, the coordinated control strategy of the DFIG-ES system with consideration of wind speed was proposed in order to improve the frequency nadir during fast-frequency response. The overall power reference of the DFIG-ES system was calculated on the basis of the frequency response characteristic of synchronous generators. In particular, once the power reference of DFIG was determined, a novel virtual inertia control method of DFIG was put forward to release rotational kinetic energy and produce power surge by means of continuously modifying the proportional coefficient of maximum power point tracking (MPPT) control. During the deceleration period, the power reference smoothly decreased with the rotor speed until it reached the MPPT curve, wherein the rotor speed could rapidly recover by virtue of wind power so that the secondary frequency drop could be avoided. Afterwards, a fuzzy logic controller (FLC) was designed to distribute output power between the DFIG and ES system according to the rotor speed of DFIG and S o C of ES; thus the scheme enabled the DFIG-ES system to respond to frequency deviation in most cases while preventing the secondary frequency drop and prolonging the service life of the DFIG-ES system. Finally, the test results, which were based on the simulation system on MATLAB/Simulink software, verified the effectiveness of the proposed control strategy by comparison with other control methods and verified the rationality of the designed fuzzy logic controller and proposed capacity allocation scheme of the ES system.