IEEE Electrification - December 2020 - 68

charge (SOC) (charge of rate) reaches a high level. After
leaving the grid, the energy-storage system is the main
source, and the output of the PV system is adjusted to
ensure the stability of the system. The nonessential load
is cut off, while the important load is retained to ensure
the stable operation of the system. In the evening, when
the output of the PV system decreases, the energy-storage system discharges to support the important load.
The off-grid system provides an additional 3,000 MWh of
power in total.

Data Analysis for Typical Scenarios
Revenue Model
The microgrid park can work in the grid-connected or
off-grid mode and use the EMS to coordinate and control
the PV power generation, energy-storage system, and
adjustable load, so that the industrial and commercial
park can achieve additional benefits in the following
three ways:
1) reducing system capacity and basic electricity
price by adjusting the PV system and energy-storage system
2) decreasing electricity charges through the PV
system while making profits from the surplus
electricity
3) participating in peak load shaving through the energystorage system and making profits through demand
response.
The dual cost reduction of " demand power fee +
electricity bill " was realized, and the distributed PV system self-use ratio was improved. Compared with the
original power distribution system, the park can save
about 2.8 GWh of electricity per year, reduce the annual electricity cost by more than 60%, reduce carbon
dioxide emission by 2,605 t, and reduce sulfur dioxide
emissions by 78 t, with good economic and environmental benefits.

Benefit Analysis
Through energy optimal dispatching, Xi'an Industrial
Park makes full use of renewable energy for power generation, effectively reduces the electricity consumption,
saves about 2.8 GWh of electricity annually, and reduces
2,605 t of CO 2 emissions. Specifically, the PV power selfuse proportion is increased by 12%, and the annual electricity charge is reduced by 60%; the basic capacity is
reduced by 10%, and the annual basic electricity fee is
reduced by 6%; and the annual electricity charge is
reduced by 6.5% by using the difference between the
peak and valley prices.
The initial investment of the project was ¥15.66 million, and the total investment was ¥18.52 million.
Through the analysis of trial operation data, the annual
income of the project is about ¥2.55 million. Considering the replacement of energy-storage batteries and

I E E E E l e c t r i f i cati o n M agaz ine / DECEMBER 2020

recovery of residual value, the total income can reach
¥63.84 million in 25 years, the internal rate of return
(IRR) of total investment is 15.2%, the annual return on
investment (ROI) can reach 16.3%, and the static investment recovery period of the project is about six years.
However, the high initial investment of the project
leads to a slightly longer payback period. The reasons
are as follows:
xx
The project was built in 2017; at that time, the costs of
the PV and energy-storage system equipment and
construction were high.
xx
The project is located in Xi'an, where PV resources
belonged to the category II area, and the average
number of annual available hours for PVs was about
1,050 h; the revenue of the PV system failed to reach
the maximum.
At present, the costs of a PV system and energystorage battery are continuously reduced. If the project
is built in a category I area with abundant solar re--
sources, the projected income will be greatly improved.
According to the results of the operation of the park
and analysis of PV data in a category I area, the IRR of
the source network load storage coordination microgrid
built in category I can be as high as 21.77%, and the ROI
can be as high as 21.77%. Compared with the traditional storage (no EMS to coordinate and optimize the operation of microgrid), the ROI increased by 8.7%, and the
energy-saving rate increased by 10.5% (including reducing the basic capacity electricity charge by 6%, increasing the PV self-use income by 2%, and saving 2.5% by
energy management). The specific indicators are
shown in Table 1.

Project Advantages and Challenges
The TBEA Park microgrid aims at commercial operation
and has good economic value and commercial promotion value. The advantages are presented as follows:
xx
The introduction of the EMS in the industrial park can
not only save electricity consumption but also reduce
emissions, achieving economic and environmental benefits.
xx
The industrial park is a typical microgrid application
scenario with high energy costs. The successful implementation of the project has effectively verified the
technical feasibility and economic value of the
microgrid.
However, there are still some challenges that need to be
addressed, which can be summarized as follows:
xx
At present, the development of microgrid parks in
China is still at the beginning stage. The lack of clear
policies and procedures for grid connection slows the
project development.
xx
The proportion of nontechnical costs (mainly the cost
when connecting to the grid) in the total cost for current microgrid projects is too high, affecting the economy of the overall projects.

IEEE Electrification - December 2020

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