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Renewable Energy Production Simulation Platform (REPS) is developed by China Electric Power Research Institute (CEPRI) to simulate the operation of renewable energy in the power system. REPS takes into account the characteristics of China’s electric power system, it can assess the accommodation of renewable energy power and simulate the impact of different renewable energy capacity on the operation of power system. Assessment model and calculation process of REPS V1.3 is introduced in this article, and annual consumptive capacity in one provincial power grid of China is evaluated with the platform. REPS is of great guiding significance to electrical source planning. With the sustained and rapid growth of renewable energy in China, power system will be more and more dependent on REPS.

Recent years, renewable energy such as wind power and photovoltaic (PV) power is emerging vigorously in the world, but due to wind power and PV power has the fluctuation and intermittence [

The majority of wind power developed countries and regions have carried out research on the accommodation of renewable energy power [

REPS regards the maximum accommodation of renewable energy power as the optimization goal, can simulate the operation of all electrical sources and load in different situations. The main features of the renewable energy production simulation platform can be summarized as follow:

Simplify the aggregation of the power network without influencing the calculation results, and the grid uses graphical polymerization modeling method which is intuitive and convenient.

Basic data and running mode is managed by the mode of network-source?load, facilitating the operators to understand data and modes.

The software is developed according to the three structures of basic data and operation mode, case calculation, calculation result and analysis, users can easily establish grid data to calculate and analyze, and all data can be shared without repeating the input operation.

The software has batch computing function, users can easily submit multiple computing cases and calculate all the results at one time to avoid waiting a long time.

The software is scalable, “plug and play” management mode is used in the case calculation model, facilitating the expansion of the software model.

The provincial power grid in China usually contains hundreds of substations and thousands of buses. Considering the physical model of whole power network is too complex, while the actual power grid is often radial, and the new energy station mainly connected to the terminal grid, there will not be many lines overload after the optimization of power network structure, so the aggregation grid model can be used to meet the requirements of the time series simulation. The aggregation model of power grid is shown in

Region A, B and C are renewable energy blocked areas which restricted by the cross section, the aggregation model is established based on the principles: a) aggregation model does not consider the detailed topological structure of the power grid, the power source and load are not affected by their physical location; b) the power consumption balance of the power network is not affected by the power network aggregation model.

Thermal power plant is an important member of the power system in China. It is very important for the accommodation of renewable energy. Thermal power units can be divided into condensing steam turbine, backpressure turbine and extraction turbine. Condensing steam turbine is exclusively for power generation, while back pressure turbine and pumping turbine can also heat, heating unit has greater influence on the accommodation of renewable energy.

1) Back pressure turbine

Back pressure turbine is a kind of heating units, its working characteristics are shown as Equation (1) and

2) Pumping turbine

The working characteristics of pumping turbine are shown as Equation (2) and

Hydroelectric power plant can be divided into two categories, one is the run-off hydropower plant without capacity of regulation, and one is adjustable hydropower plant with adjustable reservoir. The operation of hydropower plant is closely related to water resources. Power generation of the run-off hydropower plant is basically determined by the flow of the river. Adjustable hydropower plant does not have minimum output limit, but reservoir inflow and reservoir capacity is the limit factors of the power output as shown in Equation (3).

The output of renewable energy can be viewed as time sequence in time series production simulation. The change characteristics of the sequence should be consistent with the actual renewable energy resources.

1) Optimization Objective

REPS regards the maximum accommodation of renewable energy power as the optimization goal, considering renewable energy output is different in different locations, so renewable energy is calculated separately for different power grid, As shown in Equation (4):

N is the total number of aggregation networks in the system, n is expressed as an aggregation power network, T is the total simulation time, t is the step,

3) Constraint Equations

Constraint Equations include reserve capacity constraint in Equation (5), load balance constraint in Equation (6), conventional unit output constraint in Equation (7)-(10), number of running units constraint in Equation (11), conventional unit power constraint in Equation (12) and regional transmission capacity constraint in Equation (13).

timized power and running number of unit j in network n at time t.

The process of renewable energy production simulation is shown below:

In the calculation of cases which based on the actual data and methods, REPS has shown the accuracy and practicability. In this paper, annual consumptive capacity of one model provincial power in China is elevated with the platform.

In the past year, accommodation of renewable energy in the model province is not effected by peak constraint, the main limiting factor is the channel stability limits, and there are two renewable energy channels in the west region, the restricted region of renewable energy accommodation is in mainly in west. The neighboring province needs transmission power from the model province in summer.

The boundary conditions of power grid operation is an important basis for the calculation of the renewable energy accommodation, the boundary conditions mainly include reserve capacity, conventional power supply mode, maximum and minimum technical output of the units, load data, renewable energy output sequence and transmission line principles. Boundary conditions of renewable energy accommodation calculation in the model province are shown in

In the annual assessment calculation of the next year, assuming the stability limit of the renewable energy channel is same with the previous year, and large-scale hydropower station will be put into operation in neighboring province, the installed renewable energy capacity of the model province is expected to increase 24 percent year- on-year, and the power network structure has little change compared to last year, so the new energy transmission channel has no change. Prediction of renewable power accommodation of the model province is shown in

The monthly consumptive capacity assessment of the model province is shown in

From the results of the simulation, we can find that the channel stability limits is the main limiting factor for renewable energy accommodation in the model province, sending ability is limited by the grid structure constraints, due to large-scale hydropower station will be put into operation in neighboring province, the neighboring province power no longer needs power from the model province in summer, so the situation of renewable energy curtailment will continue.

This paper introduces the assessment model and calculation process of REPS V1.3, and annual consumptive capacity of one provincial model power grid is evaluated with the platform. REPS regards the maximum accommodation of renewable energy power as the optimization goal, the main functions can be summarized as follows:

Number | Boundary Condition | Calculation Principle |
---|---|---|

1 | Reserve capacity | Max{5% of the maximum load, maximum capacity of the single unit within the network}; Predictive wind power deduce 20% installed capacity to participate on power balance |

2 | Conventional power supply mode | Minimum period for the unit start and stop is once a week |

3 | Maximum and minimum technical output of the thermal power units | Minimum operating mode provided by Electric Supervision Bureau |

4 | Load data | The same as the previous year |

5 | Constraint conditions of hydropower units in electricity power balance | Maximum and minimum technical output is determined according to the actual operation requirements; utilization hours is in accordance with average water year or nearly three years |

6 | Annual renewable energy utilization hours | According to the average level of the past three years to calculate |

7 | Renewable energy time sequence | Renewable energy time sequence recovered from actual output data of the previous year |

8 | Transmission line principle | Transmission line mode is fixed, arranged respectively in different months |

Title | Calculation Result | ||
---|---|---|---|

Power generation | Expected power generation (billion kWh) | 7.226 | |

Power generation increase by (%) | +24.16 | ||

Expected utilization hours (h) | 1520 | ||

Utilization hours increase by (%) | −4.34 | ||

Power curtailment | Expected renewable energy curtailment (billion kWh) | 0.324 | |

Renewable energy curtailment increase by (%) | +260 | ||

Expected renewable energy curtailment rate (%) | 4.29 | ||

Renewable energy curtailment rate increase by | +2.79 | ||

Blocked channel: Blocked peak | 10:0 | ||

According to the historical operating characteristics of wind power and PV power, build the renewable energy time sequence which can be used for simulation calculation.

In the case of known renewable energy capacity, simulates future renewable energy power output and power limit monthly and yearly.

Simulates the impact of different renewable energy capacity on the operation of power system, including the starting and stopping power units, utilization hours and so on.

With different conventional power startup modes and load regulation characteristics, simulates renewable energy power output and limit, the advice of renewable energy construction and the conventional power operation mode are proposed.

Simulates renewable energy power output and limit with different system backup, proposed priority accommodation of renewable energy to the grid.

Simulates development planning and layout optimization of the renewable energy, the advice of planning capacity and construction sites for renewable energy are proposed.

With the vigorously emerging renewable energy in China, REPS which takes into account the characteristics of China’s electric power system will be more and more important in electrical source planning.

Jing Wang,Yunfeng Gao,Yuehui Huang,Yuefeng Wang,Jietan Zhang, (2015) Sketch of Renewable Energy Production Simulation Platform. World Journal of Engineering and Technology,03,65-71. doi: 10.4236/wjet.2015.33C010