A Self-Regulation Strategy for the Power Fluctuation of the Islanded Voltage Source Converter (VSC) Station Delivering Large-Scale Wind Power

Abstract

When the power source of a voltage source converter (VSC) station at the sending end solely depends on wind power generation, the station is operating in an islanding mode. In this case, the power fluctuation of the wind power will be entirely transmitted to the receiving-end grid. A self-regulation scheme of power fluctuation is proposed in this paper to solve this problem. Firstly, we investigated the short-time variability characteristic of the wind power in a multi-terminal direct-current (MTDC) project in China. Then we designed a virtual frequency (VF) control strategy at the VSC station based on the common constant voltage constant frequency (CVCF) control of VSC station. By cooperating with the primary frequency regulation (PFR) control at the wind farms, the self-regulation of active power pooling at the VSC station was realized. The control parameters of VF and PFR control were carefully settled through the steady-state analysis of the MTDC grid. The self-regulation effect had been demonstrated by a twenty-four-hour simulation. The results showed that the proposed scheme could effectively smoothen the power fluctuation.

Grid Connected PV Based Grid Forming Inverter with Decoupled DC Bus Controller

“…The internal control algorithm of grid-connected VSC dominated its external characteristics. Conventional VSCs are controlled at maximum power point tracking (MPPT) such that the VSC behaves as a power source with no response to grid voltage and frequency fluctuation (constant voltage constant frequency CVCF) [3], [4]. As a result, conventional VSC has no inertia and frequency regulation capacity, which cannot fulfill the modern grid code requirements [5], [6].…”

Unbalanced Current Reduction Method of Microgrid Based on Power Conversion System Operation

“…Worldwide, countries are expanding the construction of renewable energy sources from existing power systems to target greenhouse gas reductions. In particular, in areas such as islands composed of small-scale independent power grids, BESS provides the voltage and frequency to the grid, rather than the existing rotating machine base operating the power system to supply power only with renewable energy [1][2][3][4][5][6][7]. In the study of "Decentralised Active Power Control Strategy for Real-Time Power Balance in an Isolated Microgrid with an Energy Storage System and Diesel Generators", the system was operated using a droop control method that controls voltage and frequency without a communication line through active and reactive power output from the inverter [8].…”

Investigation and Control of Damping in VSC–MTDC System with DC Circuit Breakers

“…The stable and safe operation of VSC-MTDC remains an ongoing challenge, because commonly used VSC topologies, such as the two-level VSC and half-bridge modular multilevel converter (MMC), cannot isolate DC faults [3][4][5]. Therefore, it is required to paralyze all the converters until the DC fault is totally cleared.…”

“…Therefore, it is required to paralyze all the converters until the DC fault is totally cleared. Presently, MMCs with faultblocking capability and DC circuit breakers (DCCBs) are regarded as the main methods to handle DC faults [5][6][7][8][9][10]. Considering the cost and technology maturity, the DCCB-based fault ride-through strategy is more suitable for VSC-MTDC applications.…”