Black-start Power Source Research Articles

Research on the Coordinated Recovery Strategy Based on Centralized Electric Vehicle Charging Station

Electric vehicles have become a crucial component of modern power systems, possessing substantial energy reserves that can be important power supplies in blackouts where the power grid has weak reserves or limited connections to other grids. In order to clarify the technical conditions and control methods of the centralized electric vehicle charging station as the black-start power source of the power grid, assuming that the centralized electric vehicle charging station can be considered a single, large-scale energy storage system, this paper proposes a three-stage coordinated recovery strategy based on the centralized electric vehicle charging station. The strategy involves three distinct stages, beginning with the establishment of AC frequency and voltage by the electric vehicle charging station to initiate the auxiliary load of the power plant. In the middle stage, considering the traditional generator has been connected, the charging station’s control mode is set to provide constant active and reactive power output, providing extra voltage and frequency support to the grid-connected generating units and crucial loads. Finally, in the later stage, control strategies are tailored to the charging power stations’ capacities, with one group of additional oscillation damping controllers, while the other group adopts additional frequency control to decrease power disturbances, ensuring a smooth recovery of the power grid. A PSCAD/EMTDC-based model was constructed to verify the proposed coordinated grid recovery strategies. The results demonstrated that the centralized station successfully established the voltage and frequency of the AC system, and the designed additional controller also made the recovery process much more stable.

Stratified Optimization Strategy Used for Restoration With Photovoltaic-Battery Energy Storage Systems as Black-Start Resources

With the rapid growth of installed capacity of photovoltaic (PV), the PV power stations equipped with energy storage (ES) have become a new type of black-start power supply. Taking the Photovoltaic-Battery Energy Storage Systems (PV-BESS) as the black-start power source can improve the black-start ability of the regional power grid and broaden the application prospect of PV power generation. In this paper, a stratified optimization strategy for black-start of PV-BESS is proposed, which combines the key issues in the process of black-start of PV-BESS. Stratified optimization strategy is divided into data analysis layer, optimization coordination layer and scheduling control layer. The data analysis layer combines the requirements of the black-start process. Firstly, the similarity matrix ranking method is used to improve the PV power prediction method. Secondly, based on probability inclination, the PV power index is designed to evaluate the feasibility of black-start by calculating the PV lower limit power and the executable probability inclination. The optimization coordination layer is based on the state space model of black-start of PV-BESS, combined with the control strategy of PV as the main part and ES as the auxiliary part, the optimization objectives of the maximum utilization rate of PV and tracking the ideal value of state of charge (SOC) of ES is formulated. The optimal model is solved by model predictive control, and the output power of PV and ES is controlled to complete the black-start process. The actual historical data in the power grid with a high proportion of PV sources are used as the basic data for simulation. The simulation of black-start based on MATLAB/Simulink verifies the rationality of the stratified optimization strategy, which provides a reference for the realization of black-start of PV-BESS.

Method for the Energy Storage Configuration of Wind Power Plants with Energy Storage Systems used for Black-Start

With the increasing participation of wind generation in the power system, a wind power plant (WPP) with an energy storage system (ESS) has become one of the options available for a black-start power source. In this article, a method for the energy storage configuration used for black-start is proposed. First, the energy storage capacity for starting a single turbine was determined. Then, a hierarchical planning model was established. This model did not consider the starting efficiency of the WPP, but it did consider the layout of the energy storage in the WPP and the balance of the terminal voltage when starting the WPP. Finally, the feasibility and value of the proposed method and model were verified in a 49.5 MW WPP with an ESS (a power rating of 2.24 MW and energy capacity of about 1.68 MWh). The result suggests that configuring an ESS with a small capacity on the side of the turbine can achieve black-start for a WPP with an ESS as the power source.

A Black Start Scheme Based on Modular Multilevel Control-High Voltage Direct Current

Modern society’s need for power and its dependence on power sources is increasing with its development. As a result the consequences of blackout accidents have become more serious. At present, only three sources can be regarded as black-start power sources, namely Line Commutate Converter-High Voltage Direct Current (LCC-HVDC), Voltage Source Converter-High Voltage Direct Current (VSC-HVDC), and microgrids. The potential of these three sources has already been demonstrated. Lately, VSC-HVDC primarily uses the Modular Multilevel Converter (MMC) topology structure, also known as MMC-HVDC. Some domestic and foreign papers have also proposed using VSC-HVDC as a black-start power source for large power failures. However, most of these studies have analyzed only 2-level or 3-level VSC-HVDC topologies and there is no MMC topology for VSC-HVDC analysis. Therefore, the conclusion that VSC-HVDC can be used as black-start power source cannot be held true for a MMC-HVDC structures. To understand the characteristics of MMC-HVDC as a black-start power source, it is necessary to analyze the MMC-HVDC converter and do a comprehensive assessment of its performance as a black-start power source. This study analyzes the feasibility of MMC-HVDC as a start power source for black start from with regards to three aspects, namely the working principle, control strategy, and implementation scheme. We designed a corresponding MMC-HVDC control strategy depending upon the analysis result. Moreover, a complete power grid restoration process is also designed according to the black-start scheme principle, which is based on the theory of MMC-HVDC as a black start power source. Finally, the whole black start process is performed in PSCAD/EMTDC. The simulation results show that the voltage and frequency of system are maintained in a steady range during the black start realization process and the validity of MMC-HVDC as a black start power source is also verified.

Optimal placement of fast cut back units based on the theory of cellular automata and agent

The thermal power generation units with the function of fast cut back could serve power for auxiliary system and keep island operation after a major blackout, so they are excellent substitute for the traditional black-start power sources. Different placement schemes for FCB units have different influence on the subsequent restoration process. Considering the locality of the emergency dispatching rules, the unpredictability of specific dispatching instructions and unexpected situations like failure of transmission line energization, a novel deduction model for network reconfiguration based on the theory of cellular automata and agent is established. Several indexes are then defined for evaluating the placement schemes for FCB units. The attribute weights determination method based on subjective and objective integration and grey relational analysis are combinatorically used to determine the optimal placement scheme for FCB unit. The effectiveness of the proposed method is validated by the test results on the New England 10-unit 39-bus power system.

Overview and Prospects of Black Start

With the rapid development of power grid, black start has been an indispensable part of power grid construction, and the gradually mature microgrid technology will play an important role in solving power system problems. Otherwise, plug-in electric vehicle will become an important load in future power grid. The black start concept, research status, black start scheme development and its verification are stated in detail; distributed generation and microgrid are introduced; the strategy about taking microgrid as black start power sources is proposed; and key technical problems existing on the combination of black start, microgrid and plug-in electric vehicle are explored according to the microgrid control and operation characteristics. On the basis of summarizing black start and microgrid research development and achievements in the globe, this paper discusses prospects of black start and provides new views and suggestions for its further research.