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Series PV Storage System and Related Control Algorithm

IP.com Disclosure Number: IPCOM000245646D
Publication Date: 2016-Mar-24
Document File: 19 page(s) / 2M

Publishing Venue

The IP.com Prior Art Database

Related People

Lin Ma: AUTHOR

Abstract

This disclsoure proposes a series storage system topology and related control. Compared with the parallel energy storage system "injecting current control", the series energy storage system is easier to realize "terminal voltage control". And due to the PV DC bus voltage are changing with different radiation and temperature condition, so the "terminal voltage control" could bring more benefits for PV generation and PV storage system. It is not only aimed for optimizing the existed storage system, but also leading us to a new branch.

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Invention Title: Series PV Storage System and Related Control Algorithm

This ID proposed a series storage system topology and related control.

Compared with the parallel energy storage system "injecting current control", the series energy storage system is easier to realize "terminal voltage control". And due to the PV DC bus voltage are changing with different radiation and temperature condition, so the "terminal voltage control" could bring more benefits for PV generation and PV storage system.

This invention is not only aimed for optimizing the existed storage system, but also leading us to a new branch.

Abstract of the Invention

Background and State of problem

1. Generally, why we need energy storage in PV system?
a. Smooth the renewable energy generation;

b. Support a micro grid;

c. UPS mode;

d. Standards requirement [1].

Figure 1: One day PV radiation of Tibet


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  Fig.1 shows the typical PV radiation curve. Fig.2 and Fig.3 show the PV storage system work scenarios.

Figure 2: Smooth the renewable energy generation

Figure 3: Support a micro grid

  After all, the active power fluctuation is undesired to see in the power system and it cannot be controlled by PV inverter itself. In order to solve this problem, the Chinese new SGCC standards - Q / GDW 617-2011 Technical Rule for PV Power Station Connected to


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with medium voltage) must follow grid power dispatching instructions:

  All medium- and large-size PV stations will be subject to power dispatching instructions including frequency control, shift peak and power reserve.

  a) Medium- and large-sized PV stations shall be equipped with active power control system.

  b) Medium- and large-sized PV stations shall receive and respond to active power and their dispatching instructions from gird operator to ensure they comply with dispatcher's requirements. Dispatching and management for medium-sized PV station connected to user inner network will be decided by grid operator.

2. The PV storage system on the market

   In order to optimize the system dynamic performance, meanwhile satisfy the local standard requirements.

   Nowadays, the energy storage systems already are on market. Most of them utilize AC parallel storage topology as Fig.4 shows. Among them, ABB PCS100 ESS [1] is a typical product as Fig.5 shows. However, actually these AC storage systems just aim for filtering the power fluctuation or support local load temporally. No special design relates with PV system.

Grid

Load

10 kV 540 V

10 kV 315 V

10 kV

480 V

 HV PV Generation System

 LV PV Generation System

 Parallel AC Storage System

PCS 100 ESS

Figure 4: AC parallel storage system


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Figure 5: ABB PCS100 ESS AC storage system [2]

Novel features

The feature of the proposed solution is:

1) Instead of connecting the storage system to PV generation system in parallel, the proposed storage system connects to PV generation system in series as Fig.6 shows;

2) The storage system and PV system are coupled in Low V...